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Watch Episode 174 Most scientists are taught to aim for precision and control. But what if that mindset blocks the very breakthroughs we seek? Dr. Eric Trinquet, a veteran innovator behind functional GPCR assays like HTRF and IP-One, believes rigid thinking is the enemy of discovery. In this podcast, he lays out the mindset that helped shape products used across biotech and academia—and why play, failure, and surprise are not risks to manage, but fuel to harness. If you’re building tools or careers in GPCR science, this is your playbook. The Innovation Trap: Why Most Scientists Think Too Narrowly Eric doesn’t mince words: many junior scientists don’t give themselves permission to explore. They think too narrowly, focus too early, and equate unexpected results with failure. This mindset, he argues, suffocates innovation. He knows the cost firsthand. “You can try, try, try—and fail, fail, fail,” Eric says. But those failures are where new paths emerge, often leading to transformative tools like the IP1 assay and Tag-lite. Instead of chasing linear progress, Eric encourages young scientists to stay playful longer—embracing both strategy and serendipity. A Quote That Stuck: “Be rigorous, but not too much. Frame your strategy, then let the serendipity occur.” — Dr. Eric Trinquet Built to Fail, Built to Win: Inside the IP1 Assay Origin Story The IP-One assay didn’t emerge from a master plan. It began with an unmet need: how to track Gq-coupled GPCR activity without the mess of calcium flux or radioactive columns. Eric and his team rejected the calcium route entirely. Instead, they focused on equilibrium-based assays and zeroed in on IP1 accumulation—pioneering a clean, high-throughput alternative. The real challenge? Convincing the field it worked. It took data, yes—but also a deep partnership with GPCR legend Terry Kenakin to bridge industry credibility with pharmacological rigor. Why This Matters: IP-One helped set a new gold standard for functional GPCR assays—shifting how compounds are evaluated for efficacy and bias. The pHSense Breakthrough: Two Dimensions of Discovery pHSense wasn’t built in a vacuum—it was born from decades of groundwork in rare earth chemistry and a “what if” mentality. Originally developed as ultra-bright lanthanide probes, the team realized they could tune these molecules to become exquisitely sensitive to pH changes. The innovation? Dual control: not just brightness but fluorescence lifetime, with drastic shifts as pH drops. That opened the door to something rare in functional pharmacology: plate-based GPCR internalization tracking that rivals (and sometimes beats) imaging or flow cytometry. Mini Timeline 🎯 Early 2000s: Trinquet leads IP1 & Tag-lite development 🧪 Mid-2010s: Rare-earth scaffold work begins 🔬 2023: pHSense probes optimized for dual pH response ✅ 2024: Endogenous GLP-1 internalization shown in beta cells 🚀 2025: Revvity launches pHSense A Day That Changed Everything: The Endogenous Receptor “Aha” Eric’s second “aha” moment with pHSense came the day his team showed internalization of endogenous GLP-1 receptors in rat beta cells—with no overexpression, no imaging, and no pharmacological interference. “We did a full dose-response and saw antagonism—all in one plate-based assay. That’s the day I knew we had something no one else had.” That result wasn’t just a technical win. It validated the broader goal: giving scientists tools to study receptors in their native, unmodified state—unlocking new questions about constitutive activity, agonist-induced internalization, and cellular dynamics. 🔄 What Changed After This Data: Trinquet pushed pHSense toward rapid commercialization—pivoting it from a research probe into a full product line. From Theory to Tool: How Great Products Get Built pHSense didn’t materialize overnight. It’s the product of layered collaborations—with Durham University chemist David Parker on the probe chemistry, and with Jean-Philippe Pin’s team in Montpellier to validate biological performance. Eric is clear: real innovation requires real partnerships. It also requires months—often years—of decisions, missteps, and refinements. From probe solubility to photophysics, from tag strategies to model systems, every variable was debated, tested, and validated. For Early-Career Scientists: Don’t confuse “final product” with overnight success. The catalog number is the last step in a years-long journey filled with messy iterations. Advice for the Next Generation: Don’t Over-Rationalize So what does Eric tell young scientists who want to build breakthrough products? “Don’t over-rationalize,” he says. At early stages, breadth matters more than precision. Cast a wide net. Follow anomalies. Build theories, but be ready to toss them. It’s a mindset shaped by decades in the lab—but it’s also a warning. Product development isn’t just about science. It’s about timing, teaming, testing, and failing smarter. 🚀 Why This Matters: Whether you’re launching a tool, starting a biotech, or running an academic lab—your mindset, not just your science, will determine what gets built. Want to hear Dr. Trinquet tell the story in his own words? 🎧 Listen to the full podcast episode here ⸻ More about Revvity pHSense Reagents GPCR Reagents Revvity on Dr. GPCR   Dr. GPCR X Revvity Collaboration ⸻ Want more like this? 👉 Join the Dr. GPCR Premium Ecosystem  for behind-the-scenes access to GPCR innovators, exclusive deep-dives, and practical tools to accelerate your research or career. 👥 Build connections. 🧪 Get insights. 🎧 Stay ahead.

Enhancing scientific exploration by concentrating on understanding inhibition to advance GPCR drug discovery This Week’s GPCR Intelligence: Every drug you design will meet an enzyme before it meets its receptor. If you want your molecules to survive first contact with biology, enzyme inhibition must be part of your core playbook. This week’s feature breaks down exactly how to think about inhibitors with rigor and speed, so you can make better decisions earlier in the pipeline. Breakthroughs this week:  Potentiation of GPCR signaling by ATP and sugar monophosphates; Pharmacology 2025; Nxera Pharma earns $10m milestone from AbbVie neurological deal. 🔍 This Week in Dr. GPCR Premium: Sneak Peek Here’s a curated, high-signal preview of what Premium Members get this week—no fluff, just the intel to keep you ahead. This week —NIH’s new GPCR biosensor push, a leadership shift at Septerna, and a bold thesis on stabilizing mutated GPCRs. Plus: top tracks to watch at GPCR Forum 2025, fresh postdoc openings at the ADME/signaling interface, and concise reads on β-agonists, phospho-barcodes, and GPCR allostery. Premium gives you the full context, links, and our editorial notes—this is just the teaser. Terry's Corner – How Enzyme Inhibition Shapes Every Discovery Program Every molecule meets an enzyme before it ever meets its receptor. Whether you’re designing a ligand, optimizing ADME, or predicting PK, enzyme inhibition defines what survives to make an impact. This week’s Terry’s Corner reframes inhibition not as background theory—but as a design lens for smarter discovery. You’ll explore how catalytic control, allosteric shifts, and CYP450 behavior rewrite the rules of pharmacology. Mastering inhibition isn’t just about avoiding drug–drug interactions. It’s about turning enzymes from barriers into a strategy. You’ll discover: How four inhibition modes (competitive, noncompetitive, mixed, uncompetitive) dictate potency, efficacy, and safety. Why CYP450 allostery can make or break translation from bench to bedside. When “inhibition” becomes activation—and how that insight fuels next-gen therapeutic design. 🎥 Live AMA with Dr. Kenakin — October 30, 12 PM EST Bring your toughest pharmacology questions and join Dr. Kenakin live. Each session shapes next month’s lessons—so your challenges guide the content. Your Membership Gives You: Proven frameworks used in real discovery programs On-demand lessons built for busy scientists A voice in future course topics Fresh, weekly content that stays relevant Live monthly AMA sessions with Dr. Kenakin Trusted insights across biotech, pharma, and academia 💎 $2,999/year — one conference cost = a full year of expert training Unlock On-Demand Yearly Access Now — Premium Members Get Over 50% Discount at Checkout ➤ The Innovation Trap: Why Playing It Safe Can Kill Breakthroughs Revvity's Dr. Eric Trinquet, the scientist behind IP-One, Tag-lite, and now pHSense, challenges conventional scientific thinking in this candid post. He argues that early-career researchers often fall into the trap of over-rationalizing too soon—missing out on the unexpected twists that lead to real innovation. From failing fast to embracing serendipity, Eric shares the mindset (and messy origin stories) that shaped tools now used across biotech and academia. Whether you’re building assays or a scientific career, this is a must-read on why risk, surprise, and strategy belong together. Read the Feature ➤ Summer Days: Appetite, Suntans, and GPCR Micro-Domains Two recent papers connect ciliary signaling, opsins, and melanocortin receptors to behaviors and skin biology. This spotlight from Montana Molecular dives into how OPN3’s modulation of MCR4 in appetite circuits and MCR1 in melanocytes highlights the power of localized cAMP and ion channel coupling to reshape physiology. If you care about compartmentalized signaling and native-state biology, this is a sharp, readable tour. Zoom into the cilium.  Why micro-domains change what “global” signaling can and can’t explain. Target specificity, not just potency.  Localized cAMP and channel coupling as levers for phenotype. New tools, new questions.  Biosensors make once-invisible dynamics assayable at scale. Read the roundup ➤ Why Dr. GPCR Premium Membership Gives You an Edge Premium delivers curated, noise-free intelligence every week: expert lectures that turn theory into tools, classified industry news with editorial context, priority alerts for the events that matter, real career leads, and must-read publications decoded for action. It’s built for scientists and teams who want fewer tabs and faster decisions—one scroll that blends structure, function, and discovery. Instead of chasing fragmented feeds, you get a single, credible source that respects your time and advances your work. If your program depends on seeing around corners—enzyme liabilities, signaling bias, translational risks—Premium keeps you moving smarter, not just faster. Quick FAQ 🔹 What’s included? The complete Weekly News digest, curated jobs, upcoming events, classified GPCR publications, on-demand expert frameworks, and member-only discounts. 🔹 Who is it for? GPCR scientists, translational pharmacologists, biotech discovery teams, and decision-makers who need fast, curated, career-relevant intelligence to stay ahead. 🔹 Why now? The pace of GPCR innovation is accelerating. Those acting on the right signals today will shape tomorrow’s breakthroughs—and avoid delays others won’t see coming. 👉 Already a Premium Member? Access this week’s full Premium Edition here ➤ What our members say "The content had enough depth to satisfy the hunger for theory while being full of practical knowledge." — DrGPCR University Attendee 🚀 Transform enzyme theory into a discovery advantage and access this week’s classified intel! Become a Premium Member today. ➤ 🎓 Full GPCR University + 🔬 200+ expert talks 🗞️ Weekly research, careers & event intelligence 🤝 Members-only networking, AMAs & matchmaking 💡 Support open resources for the global GPCR field 🧠 Designed for researchers at every career stage

Most drugs don’t fail at the receptor level—they fail before they even reach it. Enzymes decide who survives. In every lab, candidates fail not because they lack potency at a receptor, but because they stumble at an unseen step: enzyme interaction . Before your GPCR ligand ever meets its receptor, it meets the enzymes that determine whether it survives long enough to act. Recognizing, predicting, and leveraging these interactions is the essence of enzyme inhibition pharmacology —the framework that connects molecular survival to clinical success. This is a critical topic that is often overlooked: how enzymes dictate drug success. In this session, you’ll gain: ✅ A clear map of how drugs interact with enzymes before, during, and after receptor binding. ✅ A strategic understanding of competitive, noncompetitive, mixed, and uncompetitive inhibition . ✅ Practical insight into how enzyme activation and inhibition shape drug safety, efficacy, and design decisions. The Overlooked Step in Every Discovery Program So what does that mean for discovery scientists designing the next generation of GPCR ligands? Even the most elegant GPCR ligand can fail if it never reaches its receptor. That reality starts with hepatic metabolism , where enzymes such as cytochrome P450s  determine a molecule’s fate. They can metabolize, inactivate, or transform your compound, sometimes into a toxic byproduct, other times into a life-saving prodrug. This lesson reframes enzyme interaction not as background noise, but as a core pharmacological event. By visualizing enzymes as dynamic molecular partners rather than static filters, drug discovery scientists can make faster, smarter optimization decisions. The takeaway? You’re not just designing for receptor activity—you’re designing for enzyme survival. Why Enzymes Once Seemed Like Magic Before modern pharmacology, enzymes were mysterious catalysts that seemed to defy chemical logic. In this lecture, you’ll revisit the early days of discovery: when scientists thought cellular chemistry bordered on alchemy. The transition from “magic” to mechanistic understanding, championed by pioneers like A.J. Clark , laid the foundation for today’s quantitative pharmacology. That same shift in mindset (seeing enzymes as predictable, targetable, quantifiable systems ) is exactly what teams need today to accelerate pipelines. It’s not nostalgia; it’s a reminder that the biggest breakthroughs often come from re-seeing what we thought we knew. Enzyme Inhibition Pharmacology: Orthosteric vs. Allosteric Control Once you see enzymes as design partners, the next question becomes: how do we control them? Enzyme inhibition isn’t one-size-fits-all. You’ll learn to distinguish orthosteric inhibition (where a molecule directly blocks the substrate’s access) from allosteric inhibition, which alters enzyme shape and activity from a distance. Why it matters: Allosteric inhibitors often retain potency under high substrate conditions, such as ATP-rich cancer cells, where orthosteric inhibitors fail. These nuances define therapeutic potential and side-effect risk. By mastering the difference, discovery teams can anticipate resistance, tune selectivity, and design molecules that adapt to real cellular environments—not just ideal assay conditions. Cytochrome P450: Friend, Foe, and FDA Focus No enzyme class is more important—or more unpredictable—than cytochrome P450s .CYP3A4 alone handles over half of all marketed drugs. It’s notoriously allosteric. Probe-dependent. And responsible for countless drug–drug interactions. Kenakin dissects how P450s can be both protective and problematic. Their broad substrate tolerance shields us from xenobiotics. But it also creates a nightmare for clinical predictability. The same compound may appear inactive in one substrate system, then wildly active in another. This lecture challenges scientists to move beyond binary inhibition data and embrace a systems-level view—because in regulatory conversations, “Does your molecule inhibit P450?”  isn’t a checkbox; it’s a survival test. The Four Faces of Enzyme Inhibition Most scientists can name “competitive” inhibition, but in this lesson, Terry makes sure everyone understands  all four archetypes: Competitive:  Substrate and inhibitor vie for the same site. Noncompetitive:  The inhibitor binds elsewhere, shutting down catalysis regardless of substrate presence. Mixed:  A hybrid effect defined by variable affinities. Uncompetitive:  Inhibitor acts only on the enzyme–substrate complex. Each mode reshapes both potency and therapeutic window. Through stories, such as how ethanol competes with methanol in cases of poisoning, you can gain insight into how simple enzyme logic translates into lifesaving interventions. These distinctions aren’t academic—they’re the rules behind every PK/PD curve you trust. When Inhibition Becomes Activation Not all enzyme interactions are suppressive. Some drugs activate  enzymes through allosteric binding, turning a passive catalytic site into a hyper-efficient engine. Explore examples of glucokinase activators  that enhance insulin release, as well as potential SIRT1   activators  linked to longevity and metabolic resilience. Understanding activation dynamics gives discovery teams a new design frontier: instead of blocking biology, they can re-tune  it. The implications extend to neurodegeneration, metabolic disease, and regenerative pharmacology—fields where fine-tuning enzyme behavior may outperform traditional antagonism. Enzymes: The Gatekeepers of Clinical Reality From early inhibitors like aspirin  and penicillin  to modern kinase modulators, enzymes have always dictated drug destiny. Yet many discovery teams still relegate them to the “ADME” checklist, rather than the strategic design space. This lesson’s core message is clear: Every molecule is judged twice—first by its receptor, then by its enzymes.Ignoring the second gatekeeper means wasting cycles, budgets, and potentially, careers. This session equips teams to see enzyme kinetics not as background theory, but as an accelerator for smarter discovery . 👉 Unlock Enzyme Inhibition — Only in Terry’s Corner ! 🎥  Coming Soon: Live AMA with Dr. Terry Kenakin This Month’s Live AMA — October 30 at 12 PM EST Join Dr. Kenakin live for an open Q&A session designed for discovery scientists. Bring your toughest pharmacology questions — from receptor bias and assay design to enzyme kinetics — and help shape next month’s discussion topics. Your Membership Includes: Frameworks proven in real discovery programs On-demand lessons  designed for busy scientists Direct input  on future course topics Weekly new releases  — always fresh, always relevant Live monthly AMA  sessions with Dr. Kenakin Content trusted by biotech, pharma, and academia 💎 $2999/year — one conference cost = a full year of expert training Premium Dr. GPCR members save 50%+  with your Weekly News code. 👉 Join Terry’s Corner & Secure Your Spot for the October 30 AMA Why Terry’s Corner The efficiency of your pipeline doesn’t hinge on one receptor—it depends on every enzyme your compound meets along the way. That’s where Terry’s Corner  gives discovery teams an edge. Here, you’ll get: Weekly lectures  that sharpen your command of how enzyme activity drives pharmacokinetics and drug design. A growing on-demand library  where enzyme inhibition, activation, and metabolism are demystified with clarity you can act on. Monthly AMAs  where you can challenge Dr. Kenakin with your own enzyme or GPCR interaction puzzles. Direct input  on future sessions—so topics match the hurdles your team faces in discovery and development. Decades of kinetic insight  reframed into actionable tools for faster, cleaner decision-making. Pharmacology isn’t just about hitting the receptor—it’s about surviving the enzymes first. If you’re still treating metabolism as an afterthought, you’re designing risk into your pipeline. 🟢 40 years of expertise at your fingertips:   Explore the complete library ➤ ✳️ Want to know what’s inside?   Read the latest articles ➤ Stay sharp between lectures.   Subscribe to The Kenakin Brief  today ➤

Enhance your GPCR research with deeper assay insights for more effective results. This Week’s GPCR Intelligence: If you want cleaner decisions, start with the system—then the ligand. This week Terry's Corner unlocks a simple lever that separates signal from storytelling, moving programs forward with fewer surprises. Breakthroughs this week: C. elegans avoids EGCG via SRXA-7 GPCR; a bidirectional GPCR switch modulates immune signaling; a machine-learning tool predicts GPCR–ligand kinetics; and cryo-EM uncovers a new allosteric site on an orphan GPCR. 🔍 This Week in Dr. GPCR Premium: Sneak Peek A fast editorial preview of what Premium Members get in full this week — so you can scan, prioritize, and act. Inside Premium:  Key FDA moves reshaping GPCR pipelines, shifting obesity and CNS strategies, and global meetings worth bookmarking. Plus: new research on CaSR, leptin signaling, and inflammation-linked GPCRs — and curated roles in computational and membrane protein science. Premium delivers the full details, links, and expert commentary every week. Terry's Corner – Assay Volume Control in GPCR Drug Discovery This week in Terry’s Corner, you’ll learn how dialing receptor expression/coupling up or down reveals hidden partial agonism, “silent” agonism, inverse agonism, and liabilities that derail translation of your GPCR drug discovery program. This isn’t academic—it’s a pipeline filter for reality-aligned decisions. See the true  pharmacology:  Lower sensitivity to uncover partial agonism and compare relative efficacy without confounders. Catch stealth behaviors early:  Boost sensitivity to expose weak agonism in “antagonists” or PAMs—before they bite you in vivo. Design for translation:  Map sensitivity ranges to tissue contexts so your plate data predicts what happens in organisms. 🎬 Plus New: Lesson Trailers   Curious about Terry’s Corner before committing? Watch our new trailers for a preview of expert-led GPCR training designed for scientists and drug hunters.   Your membership gives you:   Proven   frameworks  for real-world GPCR drug discovery Flexible , on-demand lessons for busy scientists Influence   the curriculum with your topic suggestions Weekly new releases  to stay ahead of the science Content built for biotech, pharma & academia Live monthly AMA with Dr. Kenakin every last Thursday of the month at 12pm EST 7-day free trial to explore the corner   💎 $2999/year — one conference cost = 12 months of expert training Unlock On-Demand Yearly Access Now — Premium Members Get Over 50% Discount at Checkout ➤ Coming Next Week on the Dr. GPCR Podcast Starting next week, new episodes will drop bi-weekly on Wednesday mornings  — giving you mid-week insights that connect science and strategy. We kick off with a question that cuts deep: What if your models could actually predict the future? In this upcoming episode, Dr. Jens Carlsson  (Uppsala University) joins Yamina  to explore how computational modeling is evolving from explanation to real prediction — and why that shift could reshape GPCR drug discovery. Prediction, it turns out, is only powerful if you understand its limits. 🎧 Catch up while you wait: → Catch up on the latest episodes → Read our podcast highlights Inside Revvity’s GPCR Journey: How Decades of Discovery Shaped pHSense From HTRF to pHSense: The Long Game of GPCR Innovation Most scientists only see the final kit—the catalog number, the plate-ready reagents. But behind every “new” assay is a decade of design, failure, and rethinking. In this behind-the-scenes look, Dr. Eric Trinquet traces how a series of bold pivots—from Cisbio’s HTRF platform to IP-One and now pHSense—reshaped how GPCR biology gets measured. It’s not just a story about a probe. It’s about how Revvity turns deep science into tools that endure. Read the full story➤ Why Dr. GPCR Premium Membership Gives You an Edge Premium delivers curated, noise-free intelligence every week: expert frameworks (on-demand), classified industry updates, priority event alerts, vetted jobs, and commentary that connects dots across pharmacology, chemistry, and computation. It’s built to compress your time to clarity—so you can pick better targets, stress-test hypotheses earlier, and focus on experiments that change decisions, not just dashboards. Fast FAQ 🔹 What’s included? The complete Weekly News digest, curated jobs, upcoming events, classified GPCR publications, exclusive on-demand expert lectures, and member-only discounts. 🔹 Who is it for? GPCR scientists, translational pharmacologists, discovery teams, and decision-makers who need fast, curated, career-relevant intelligence to stay ahead. 🔹 Why now? GPCR innovation is accelerating. Acting on the right signals today prevents tomorrow’s delays—and puts you ahead when budgets and timelines tighten. 👉 Already a Premium Member? Access this week’s full Premium Edition here ➤ What our members say "Thank you for bringing this course with Dr. Kenakin. I wish Dr. GPCR the best for the sake of promoting more educational opportunities that are sorely needed in the field." — DrGPCR University Attendee 🚀 Make better calls with better inputs. Become a Premium Member today. ➤ 🎓 Full GPCR University + 🔬 200+ expert talks 🗞️ Weekly research, careers & event intelligence 🤝 Members-only networking, AMAs & matchmaking 💡 Support open resources for the global GPCR field 🧠 Designed for researchers at every career stage

Exploring the foundational stages of scientific breakthroughs with Eric Trinquet, highlighting that true innovation begins well before laboratory experiments. Featuring logos from Dr. GPCR and Revvity. Watch Episode 174 Most scientists only see the final kit—the catalog number, the plate-ready reagents. But the reality? Every GPCR assay that makes it to market carries years of failures, late-night ideas, risky bets, and off-script breakthroughs. In this behind-the-scenes look at the making of Revity’s pHSense, Dr. Eric Trinquet shares what it really takes to bring a product to life—from sketch to shelf. If you’re in GPCR discovery or biotech R&D, this is a masterclass in turning deep science into scalable tools. From Platform to Pivot: The Birth of HTRF The journey to pHSense didn’t begin with a probe. It began with a diagnostic company rethinking its core technology. Dr. Eric Trinquet joined Cisbio in the early 2000s, working on what would become HTRF—Homogeneous Time-Resolved Fluorescence. Initially applied to biomarkers in blood, its no-wash, miniaturized design caught the attention of high-throughput screeners. But there was a pivot: the tech had untapped potential for GPCRs. Functional assays for GPCRs—especially Gq-coupled receptors—were notoriously messy. Calcium flux? Not stable. IP3 detection? Radioactive and cumbersome. Trinquet’s team asked a bolder question: could they design equilibrium-based assays for pathways no one had touched before? They didn’t just ask. They delivered. Why This Matters: The GPCR toolkit scientists use today—cAMP, IP-One, and now pHSense—didn’t evolve incrementally. It was born from radical rethinking of assay design, where platform constraints became product opportunities. Built to Fail, Built to Win: The IP One Gamble After the success of their cAMP assay, Trinquet’s team took a risky bet: develop a functional readout for Gq signaling without relying on calcium. That meant targeting inositol monophosphate (IP1), a stable downstream marker of IP3. But the path wasn’t clear. Months were spent debating assay design. IP1 isn’t naturally abundant or easy to detect. The gold standard was still radioactive tracers and purification columns. Eventually, the team landed on a design that could accumulate and detect IP1 in a 384-well format. They benchmarked it against the radioactive gold standards—and it held up. “The IP-One project was one of the riskiest things we did. But the moment we got bench-level data that aligned with our design—it became a breakthrough.” — Dr. Eric Trinquet The Real Work Starts Before the Lab What most scientists don’t see is how long a product exists as theory before it exists as a neatly packaged kit. pHSense was no different. It started not with biology—but with chemistry. Revvity and academic collaborator Prof. David Parker spent years designing rare-earth europium probes. The goal wasn’t to build a pH sensor—it was to create brighter, more stable lanthanide complexes for HTRF. But a pattern emerged: some scaffolds showed dual responsiveness to pH through lifetime and brightness modulation. That opened the door to a 2D sensor—one that responded cleanly to endosomal acidification with unmatched sensitivity. Classic pH probes failed in plate readers—too noisy, too dim. pHSense rewrote that rule, enabling high-throughput GPCR internalization assays without imaging. Internalization as a Functional Readout The insight? GPCR internalization isn’t just a trafficking readout—it’s pharmacology. Trinquet’s team designed pHSense to detect that, without microscopy. By covalently attaching the probe to FLAG-tagged receptors or using labeled antibodies, they created a plug-and-play assay format. More importantly, it worked across formats: from overexpression systems to endogenous GPCRs in native beta cells. Their “aha” moment came when they ran a dose-response with Exendin-4 on GLP-1 receptors—and saw clean, plate-based internalization curves without needing a single image. Mini Timeline: The Road to pHSense → Initial lanthanide probe design with Durham University (chemistry) → Discovery of pH-sensitive dual response (brightness + lifetime) → Application to GPCR models with Jean-Philippe Pin’s lab → Breakthrough internalization data in endogenous cells expressing GLP-1R → Commercial launch of pHSense as a plate-ready assay Real Partnerships, Not Just Sponsorships Behind every breakthrough assay is a web of collaborations that rarely make the brochure. Revnity’s partnership with Durham (chemistry) and the Institute of Functional Genomics in Montpellier (GPCR pharmacology) was not transactional. It was a scientific co-creation. Academic labs tested, challenged, and refined the tools. The result was not just a reagent—but a validated method to explore GPCR function across systems and species. And this ethos continues: every product is just the beginning of a feedback loop, where customer data feeds the next generation of design. For Early-Career Scientists: If you want to work in product R&D, learn this: real innovation happens in the tension between rigor and serendipity. You’ll fail 90% of the time. The fun is what you do with the other 10%. 🎯 From Launch to Legacy For Dr. Trinquet, commercialization isn’t the end of a project—it’s a milestone in a longer journey. It’s when you invite the community in. It’s when the tools you built in-house meet the problems no one saw coming. pHSense isn’t just a probe. It’s a strategic tool for decoding GPCR behavior in drug discovery and systems biology. It reflects decades of foundational R&D—from the fluorescent probes of Cisbio’s early days to the receptor-targeting strategies of today. And for those on the front lines of GPCR science, it’s a new lens to see what’s always been there—just below the surface. Want to hear Dr. Trinquet tell the story in his own words? 🎧 Listen to the full podcast episode here ⸻ More about Revvity pHSense Reagents GPCR Reagents Revvity on Dr. GPCR   Dr. GPCR X Revvity Collaboration ⸻ Want more like this? 👉 Join the Dr. GPCR Premium Ecosystem  for behind-the-scenes access to GPCR innovators, exclusive deep-dives, and practical tools to accelerate your research or career. 👥 Build connections. 🧪 Get insights. 🎧 Stay ahead.

Every delay in the discovery pipeline compounds into wasted years, lost opportunities, and soaring costs. For drug hunters working at the GPCR interface, the difference between a successful lead and a dead-end candidate often comes down to one overlooked factor: system sensitivity and how we control it. Assay sensitivity is like adjusting the brightness on a microscope—set it right, and hidden details jump into focus, changing the story entirely.  For GPCR drug discovery, those hidden details can determine whether a compound advances or stalls. Pharmacology isn’t only about ligands, receptors, and downstream G protein signaling—it’s also about recognizing that the assay itself holds powerful information when tuned correctly. In this course, you’ll gain: ✅ How assay volume control  alters receptor sensitivity and what that reveals about candidate drugs. ✅ Why adjusting system sensitivity  can uncover hidden efficacy, silent antagonism, or even inverse agonism. ✅ Practical insights into designing assays that mimic pathophysiology , producing data with sharper predictive power. The Hidden Lever in GPCR Research In GPCR pharmacology, the conversation often centers on ligand properties—affinity, selectivity, efficacy. But what if the assay system itself  could be leveraged as a powerful experimental variable? Assay volume control does just that. By modulating receptor expression or sensitivity, we can shift the “lens” through which drug activity is revealed. For discovery teams, this isn’t an academic exercise. It’s about revealing therapeutic liabilities before  they derail development. A drug candidate that looks promising in a high-sensitivity assay may collapse under physiological stress. Conversely, a weak signal in a baseline assay may mask an opportunity—if the system were tuned differently, hidden efficacy could be exposed. The real question: are you letting your assay system dictate the wrong story? Why System Sensitivity Matters Consider the signaling cascade: ligand binds receptor, receptor couples to G protein, G protein initiates downstream events. The quantitative strength of this cascade depends not just on the ligand, but also on the abundance and coupling efficiency of the receptor system . By reducing receptor density, researchers can transform full agonists into partial ones—allowing comparative efficacy calculations that are otherwise invisible. By increasing sensitivity, so-called “silent” antagonists reveal themselves as weak agonists. With extreme overexpression, constitutive activity emerges, exposing inverse agonism.  Think of it this way: most receptors behave like switches—they stay off until flipped. But some leak current, like a switch glowing faintly in the dark. That’s constitutive activity—and it’s what lets us see inverse agonism when we crank the system up. The ability to dial  system sensitivity up or down creates a testbed where drug behaviors that normally remain hidden can be observed in sharp relief. Questions That Make or Break a Program This session doesn’t overwhelm with technical deep-dives—it teases apart practical insights by asking: How can you distinguish between a high-affinity/low-efficacy agonist  versus a high-efficacy agonist  before entering costly development phases? What if your “silent antagonist” is actually a low-level agonist in disguise—and how will that matter in vivo? Can changing receptor density predict how your drug will behave across sensitive versus less sensitive tissues? What role does constitutive activity play in uncovering inverse agonists , and how can you exploit this phenomenon for novel therapeutic strategies? These aren’t abstract academic puzzles—they’re decision points that can make or break a program. Pipeline Payoff: Assay Sensitivity for Better Predictions For drug discovery scientists, time and predictive accuracy are the currency of success. An assay that reveals drug properties earlier in the pipeline translates directly into better prioritization, cleaner data packages, and fewer late-stage surprises. Volume control strategies turn basic receptor assays into diagnostic tools that: Differentiate compounds beyond surface-level potency. Model patient-like pathophysiological states (e.g., reduced receptor expression in heart failure). Clarify whether observed effects reflect true pharmacology or assay artifacts . Every mischaracterized compound that enters animal studies or early trials is a tax on time and resources. Adjusting assay sensitivity—whether through expression systems, chemical modulation, or engineered desensitization—provides the clarity needed to avoid these detours. From Bench Insight to Strategic Advantage Terry Kenakin’s decades of pharmacology leadership converge on one principle: pipeline advantage begins with sharper experiments . Emerging drug hunters cannot afford to test compounds in default conditions alone. Instead, they must ask how the assay itself can be tuned to better mirror the biological and clinical reality. What emerges is not just more data—it’s the right data, positioned to inform strategic decision-making. Assay volume control becomes a tool for risk management, translational prediction, and mechanistic insight. In an era of accelerated GPCR-targeting innovation, these advantages define which programs advance and which stall. Unlock Assay Volume Control Only in Terry’s Corner 🎬 Watch Course Trailers Not sure yet? Get a preview of Terry’s teaching style and see why drug hunters worldwide rely on his frameworks. Short trailers give you a front-row seat before you commit. Why Members Join: Frameworks proven in discovery programs On-demand lessons built for busy scientists Influence the curriculum with your topic suggestions Weekly new releases — always fresh, always relevant Live monthly AMA with Dr. Kenakin Content trusted by biotech, pharma & academia 💎 $2999/year — one conference cost = a full year of expert training  (Premium Dr. GPCR members save 50%+ with your Weekly News code) 👉   Explore Trailers & Join Today Why Terry’s Corner The pharmacology landscape is dynamic—ligands compete, cooperate, and reshape receptor ensembles in ways that standard models often miss. That’s where Terry’s Corner  changes the game. Here, you’ll get: Weekly lectures  that sharpen the exact tools you rely on in discovery. A growing on-demand library  of expert pharmacology lessons to revisit anytime. Monthly AMAs  where you can challenge Terry with your toughest questions. Direct input  on future topics, aligning content with your team’s real-world needs. Decades of insight distilled  into frameworks you can apply immediately. Pipeline efficiency isn’t luck—it’s literacy. If you’re still treating orthosteric and allosteric interactions as interchangeable, you’re leaving precision (and money) on the table. 🟢 40 years of expertise at your fingertips:   Explore the complete library ➤ ✳️ Want to know what’s inside?   Read the latest articles ➤ Stay sharp between lectures.   Subscribe to The Kenakin Brief  today ➤

This week’s edition links ligand mechanism to the decisions that shape affinity, efficacy, selectivity, safety, and downstream assays. Welcome to this week’s Dr. GPCR Weekly News Free Edition—your clear, credible signal in a noisy field. Each week we highlight the decisions that move GPCR projects forward—from pharmacology essentials to ligand binding site strategies, bench-ready tools, and industry momentum shaping GPCR pipelines. Read fast, apply faster, and stay ahead in GPCR drug discovery with evidence-based insights—no hype, just strategies you can use. Breakthroughs this week: New work clarifies how active-state GPCR conformations can support coupling to multiple transducers; plus obesity-drug program milestones and company pipeline updates. 🔍 This Week in Dr. GPCR Premium: Sneak Peek A fast, editorial preview of what Premium Members are reading in full this week—curated, concise, career-relevant. Industry insights:  Fresh selectivity datasets on openMe; Novo’s obesity dominance faces new challengers; integrating AI + structure + throughput to accelerate GPCR programs; key psychiatry and obesity updates and a noteworthy oncology first-in-patient milestone. Upcoming events:  Practical sessions on GPCR internalization and soluble proteins; core meetings from GPCR Forum to Biophysics; plus targeted summits for discovery teams planning 2025–2026. Career opportunities:  Roles spanning research associates to principal scientists across membrane proteins, antibody production, and ion channels. Must-read publications:  Studies on active-state GPCR ensembles and their transducer coupling, biased angiotensin receptor ligands, and circuit-selective analgesia in pain models. Terry's Corner – Orthosteric vs. Allosteric Interactions When should you push the native system—and when should you partner with it? This week in Terry's Corner, we focuse on the distinction between orthosteric and allosteric mechanisms and the impact of this choice on affinity, efficacy, safety, and downstream decision-making. If your team is arguing about “potency vs. effect size vs. duration,” this is your playbook for aligning strategy with biology and avoiding preventable rework. You’ll learn how to: Solve the override vs. finesse dilemma:  When orthosterics hijack the signal vs. when allosterics fine-tune (and why that matters for target exposure and safety). Win on kinetics, not just Kd:  Dynamic binding means “affinity” moves—design readouts and decisions that respect receptor state lifecycles. Separate effect size from time:  Use allosteric modulators to expand therapeutic index and reduce overdose risk without sacrificing meaningful efficacy. 🎬 Plus New: Lesson Trailers   Curious about Terry’s Corner before committing? Watch our new trailers for a preview of expert-led GPCR training designed for scientists and drug hunters.   Your membership gives you:   📚 Proven frameworks for real-world discovery 🌍 Flexible, on-demand lessons for busy scientists 💡 Influence the curriculum with your topic suggestions 🆕 Weekly new releases to stay ahead of the science 🧠 Content built for biotech, pharma & academia 💬 Live monthly AMA with Dr. Kenakin     💎 $2999/year — one conference cost = 12 months of expert training  Premium Dr. GPCR members save  50%+  (check your Weekly News code).   👉 Explore Trailers & Join Today Inside Revvity's R&D: How pHSense Was Born The day your data surprises you—in the best possible way—is the day you know you’re onto something. For Dr. Eric Trinquet and his team at Revvity, that moment came when they watched GPCRs internalize in native beta cells—without engineered tags, radioactive tracers, or complex imaging setups. Instead, the signal came clean, scalable, and unmistakably real. It wasn’t luck. It was persistence. Years of chemistry, photophysics, and pharmacology condensed into one breakthrough: pHSense , a reagent designed to make receptor trafficking visible in the systems that matter most. From Bench Frustrations to Breakthrough Design For decades, GPCR trafficking research relied on overexpression and fluorescent imaging—powerful, yes, but far from physiological. The Revvity team asked a harder question: What if you could measure receptor internalization in native cells, without distorting biology? The answer was anything but straightforward. Rare-earth europium complexes offered potential—but the chemistry was brutal. Solubility issues, fragile photophysical properties, endless false starts. That’s where collaboration came in. Working closely with Professor David Parker of Durham University, Trinquet’s group cracked the scaffold. By carefully tuning both brightness and fluorescence lifetime, they engineered a two-dimensional pH response: probes that get brighter and glow longer as receptors descend into acidic endosomes. “You’re not changing the spectrum,” Trinquet explains. “You’re changing how bright it is—and how long it glows.” That subtle distinction opened the door to a brand-new assay format. Why It Matters Instead of imaging-heavy workflows, pHSense offers a no-wash, plate-reader–ready, high-throughput assay  that finally connects internalization readouts with physiological relevance. Available in four formats, it turns a notoriously tricky measurement into something discovery teams can actually scale—without sacrificing biological fidelity. And perhaps that’s the deeper story: Revvity’s R&D team didn’t just invent another tool. They translated a fundamental principle of chemistry into a usable platform for pharmacology—showing how persistence, precision, and the courage to take on “impossible” chemistry can shift the entire GPCR toolkit. 👉 Go behind the scenes with Revvity’s R&D team ➤ Celtarys Research – Advantages of Fluorescent Ligands in CNS GPCR Drug Discovery In neuroscience drug discovery, the right tool  can be just as critical as the right target . For GPCRs, fluorescent ligands have quietly become one of the most versatile technologies—supporting everything from hit validation to pre-clinical assays. Why? Because they give researchers something rare in CNS work: clarity in complexity. The Advantages Live-cell imaging:  visualize receptor–ligand interactions in real time, without disturbing native cell states. Subtype specificity:  selectively track receptor subtypes in complex brain tissue. Cleaner data:  higher signal-to-noise ratios sharpen CNS assays. Speed:  faster GPCR target validation and assay development. Safety:  a non-radioactive alternative, sidestepping regulatory hurdles. Why It Matters In the CNS, where receptor localization and real-time signaling shape therapeutic outcomes, fluorescent ligands deliver both precision and adaptability. B y integrating them into GPCR workflows, discovery teams can accelerate identification, characterization, and lead optimization—reducing noise while increasing confidence in every step. 👉 See how fluorescent ligands sharpen CNS drug discovery ➤ Why Dr. GPCR Premium Membership Gives You an Edge Premium provides weekly curated intelligence, including expert lectures, classified industry news, priority event alerts, focused job leads, and insider commentary. It's designed to help GPCR scientists and teams move faster by consolidating scattered updates into a single actionable stream. From assay choices to investment-grade context, you’ll see the signal early, cut delays, and make cleaner portfolio decisions while supporting open resources for the global GPCR field. FAQ: Premium Membership 🔹 What’s included? The complete Weekly News digest, curated jobs, key upcoming events, classified GPCR publications, on-demand expert frameworks, and member-only discounts. 🔹 Who is it for? GPCR scientists, translational pharmacologists, biotech discovery teams, and decision-makers who need fast, curated, career-relevant intelligence to stay ahead. 🔹 Why now? The pace of GPCR innovation is accelerating. Acting on the right signals today shapes tomorrow’s breakthroughs—and avoids slowdowns others won’t see coming. 👉 Already a Premium Member? Access this week’s full Premium Edition here ➤ What our members say "This came at just the most perfect time… it’s just like being at a conference getting new ideas. 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Every R&D team is under the same pressure: deliver validated targets, clean pharmacology, and translatable in vivo results—faster. But here’s the truth: too many programs still fail because early decisions were built on shaky mechanistic ground. The cost? Months of wasted resources, failed translation, and opportunity loss. The difference between orthosteric vs. allosteric mechanisms isn’t just academic — an orthosteric antagonist can hijack receptor physiology, while an allosteric modulator works with the system. That choice determines whether you risk over- or under-dosing, miss safety windows, or miss therapeutic breakthroughs. In this session, you’ll gain: ✅Clarity on Definitions:  What truly distinguishes orthosteric from allosteric interactions. ✅ Insight into Consequences:  How binding sites determine receptor state shifts, signaling outcomes, and efficacy profiles. ✅ Practical Perspective:  Why this knowledge reshapes dose–response interpretation and informs your pipeline’s next decision gate. Why Orthosteric vs. Allosteric Interactions Still Matter Orthosteric and allosteric interactions have been in pharmacology textbooks for decades, but today they’re strategic levers. Orthosteric ligands preempt  natural signaling; they “take over” receptor behavior, forcing physiology to follow their lead. That can be powerful but blunt. Allosterics , in contrast, act more like tuning knobs—modulating receptor ensembles in partnership with the system’s ongoing signaling. This means they can be more selective, avoid pathway saturation, and preserve physiological nuance. For drug discovery teams navigating safety margins, biased signaling, and combination therapy design, understanding which approach you’re taking is mission-critical. In this lesson, you’ll learn why this distinction is not just theory, but a practical framework to design cleaner, smarter pharmacology. The Dynamic Nature of Receptor Binding Forget the static “lock-and-key” metaphor. Ligands bounce in and out of receptor sites, competing dynamically. Orthosteric sites are zero-sum: highest affinity or concentration wins. Allosteric sites operate differently: ligands bind elsewhere, transmit energy changes, and shift the receptor ensemble’s state without direct competition. Dr. Kenakin walks through this as a living system , showing how GPCRs exist in multiple conformations and how your ligand’s presence reshapes the ensemble. This has immediate implications for interpreting EC50 shifts, partial agonism, and assay readouts—especially in systems with constitutive activity. How Conformational Changes Drive Affinity and Efficacy A key takeaway from this session: affinity and efficacy are not independent variables—they’re thermodynamically linked. A high-affinity ligand often has higher efficacy, but the relationship is not linear. By stabilizing certain receptor states over others, ligands literally remodel the energy landscape. For teams building structure–activity relationships (SAR), this insight is gold: you’re not just chasing Ki or EC50 values—you’re sculpting state probabilities. That perspective helps explain why two compounds with similar affinities can deliver very different clinical profiles. Why Allosteric Modulators Expand Your Toolkit Allosterics offer a broader range of effects—additive, synergistic, or even inhibitory—depending on cooperativity (α, β) with endogenous agonists. Unlike orthosterics, they can discriminate between agonists, pathways, and even durations of action. This means you can design molecules that potentiate beneficial pathways without shutting down basal signaling entirely, or conversely, selectively dampen overactive pathways without full receptor blockade. The result? More nuanced control, fewer off-target liabilities, and novel therapeutic windows. The Mechanistic Edge Behind Smarter Drug Discovery One of the most powerful aspects of this session is how it reframes the questions you ask of your own data. Instead of treating binding as a binary event, Terry shows you how to interrogate whether your compound acts orthosterically, allosterically, or with mixed mechanisms—and why that matters for interpreting EC₅₀ shifts and constitutive activity. You’ll learn to recognize when an inverse agonist is resetting a receptor’s set point, when a partial agonist is competing with endogenous tone, and when an allosteric modulator is adding to or potentiating the natural response. The result is not just cleaner assay design but a sharper decision framework for selecting, prioritizing, and dosing your lead series. Translational Relevance: From Bench to Clinic Misjudging orthosteric vs allosteric behavior can derail dose selection, lead to false negatives in early screens, or even mask toxicities. Correctly distinguishing these mechanisms helps refine therapeutic index calculations, prioritize safer leads, and avoid late-stage surprises. In drug discovery, orthosteric vs. allosteric isn’t just a mechanistic detail; it’s a decision that shapes your pipeline’s success. Recognizing how your ligand interacts with the receptor lets you predict safety margins, dose–response behavior, and translational risk before they derail development. Equip your team with this literacy now to design cleaner pharmacology and accelerate smarter, safer programs. Unlock Orthosteric vs. Allosteric Interactions Only in Terry’s Corner 🎬 Plus New: Lesson Trailers   Curious about Terry’s Corner before committing? Watch our new trailers for a preview of expert-led GPCR training designed for scientists and drug hunters.   Your membership gives you:   📚 Proven frameworks for real-world discovery 🌍 Flexible, on-demand lessons for busy scientists 💡 Influence the curriculum with your topic suggestions 🆕 Weekly new releases to stay ahead of the science 🧠 Content built for biotech, pharma & academia 💬 Live monthly AMA with Dr. Kenakin     💎 $2999/year — one conference cost = 12 months of expert training  Premium Dr. GPCR members save  50%+  (check your Weekly News code).   👉 Explore Trailers & Join Today Why Terry’s Corner The reality is dynamic—ligands compete, cooperate, and reshape receptor ensembles in ways that standard models miss. That’s where Terry’s Corner changes the game. Here, you’ll get: Weekly lectures  that sharpen the tools you actually use in discovery A growing on-demand library  of expert pharmacology lessons you can revisit anytime Monthly AMAs  where you can ask Terry your toughest questions Direct input  on future topics, so the content tracks your team’s challenges Decades of insight distilled  into frameworks you can apply immediately Pipeline efficiency isn’t luck—it’s literacy. If your team is still treating orthosteric and allosteric interactions as interchangeable, you’re leaving precision (and money) on the table. 🟢 40 years of expertise at your fingertips:   Explore the complete library ➤ ✳️ Want to know what’s inside?   Read the latest articles ➤ Stay sharp between lectures.   Subscribe to The Kenakin Brief  today ➤

What is Homogeneous Time-Resolved Fluorescence (HTRF)? HTRF is a hybrid detection technology that combines Förster Resonance Energy Transfer (FRET) with a time-resolved measurement . FRET is a distance-dependant energy transfer between a donor and an acceptor fluorophore, and in HTRF a delay is introduced between the time of excitation of the donor and the readout of the acceptor’s emission. The donors used in this technique have longer half-lives  than other fluorophores (between 300μs–1 ms) and can be combined with the same acceptor fluorophores used in regular FRET assays. Terbium, a second-generation donor, is brighter than Europium (10-20 times), which increases sensitivity. When the distance between donor and acceptor is close enough, energy is transferred, and a second, short-lived emission is recorded. Measuring emission at both donor (usually 620nm) and acceptor (typically 665nm) wavelengths allows for data correction , reducing variability. Figure 1. Principle of time-resolved detection. Source: Nørskov-Lauritsen L, Thomsen AR, Bräuner-Osborne H. G protein-coupled receptor signaling analysis using homogenous time-resolved Förster resonance energy transfer (HTRF®) technology. Int J Mol Sci. 2014 Feb 13;15(2):2554-72. The delay introduced in HTRF between excitation and emission detection lets the background signals dissipate , reducing the impact of background interference (from autofluorescence or light scattering). This makes it an ideal candidate for GPCR research, where accuracy in detecting subtle signaling changes is essential. Homogeneous Time-Resolved Fluorescence Assays: Overcoming Common Challenges Balancing sensitivity and scalability  is one of the hardest challenges in high-throughput screening (HTS). Traditional methods like radioligand binding assays or calcium flux measurements have significant drawbacks in this context: one is limited by radioactivity-related safety and environmental concerns, while the other one has high background noise and low dynamic range. How are these challenges overcome by HTRF? No washing. Use of 384 or 1536-well plates and compatibility with automated platforms. Signal interferences are kept to a minimum thanks to the timing of detection. The ratiometric readouts correct many inconsistencies such as pipetting errors. The donor lanthanum fluorophores are more stable than regular fluorophores and quite resistant to photobleaching. The donors act as light-harvesting antennas, capturing light from all directions, unlike the dipole-dipole alignment needed in FRET. Enhancing HTRF Assay Performance in GPCR Research Using Fluorescent Ligands GPCRs are involved in numerous physiological processes, making them a key target in drug development.  They activate several signaling pathways, via G proteins, β-arrestins, receptor tyrosine kinases, making them a complex task to study. GPCRs are not always the most numerous in cells. Quite often, there is a need to amplify the signal  strength to detect them, which can be achieved by using fluorescent ligands. This is moreso the case when detecting partial agonism or weak receptor interactions. This technology enhances sensitivity and assay specificity . By using two labeled ligands the transference of energy event will only happen when the adequate distance is achieved. This means that even if one of the ligands they are bound to is promiscuous, it will not compromise assay integrity the same way it would in single-label approaches. This is especially useful in GPCRs, where structural similarity happens often and thus cross-reactivity of ligands is common. In HTRF the lanthanide-based donors with longer emission enhance signal-to-noise ratio and red uce background interference . They can be combined with second generation acceptors like d2, as well as brighter donors, further increasing sensitivity and assay specificity. This also improves detection of low affinity or slow binding ligands. On top of that, smaller acceptors like d2 reduce steric hindrance, making them more efficient. It can also be combined with  multiplexing . By using donor-acceptor pairs with different emission spectra that don’t overlap, researchers can design assays that track multiple pathways at the same time. Terbium is compatible with both red and green acceptors. This has been done in assays tracking IP1 and cAMP to detect biased agonism in GPCR ligands Table 1. Examples of HTRF donor/acceptor pairs Expanding Time-Resolved Fluorescence Applications in Drug Discovery Beyond Traditional Methods At Celtarys, we have expertise in time-resolved fluorescence applications. In a recent study , we contributed to the development of a robust HTRF assay for the discovery of new modulators for cannabinoid receptors. This assay utilized our fluorescent ligand, CELT-335 , designed for hCB 1 /CB 2  cannabinoid receptors, demonstrating high specificity and sensitivity in detecting ligand-receptor interactions.  Figure 2. Saturation assays using CELT-335. Specific binding is shown, obtained from total binding and unspecific binding (a) CB1R expressing adherent HEK-293T cells and unspecific binding measurement (specific binding measured using CP55490 at 10 μM concentration ) (b) CB 2 R expressing adherent HEK-293T cells and unspecific binding measurement (specific binding measured using GW405833  at 10 μM concentration). Data represent the mean ± SEM (n = 3 in triplicate). Source: Navarro G, Sotelo E, Raïch I, Loza MI, Brea J, Majellaro M. A Robust and Efficient FRET-Based Assay for Cannabinoid Receptor Ligands Discovery. Molecules. 2023 Dec 15;28(24):8107.   Celtarys enhances the power of HTRF and other FRET-based technologies by providing high-performance fluorescent ligands designed specifically for pharmacological research. By combining deep expertise in GPCR biology with advanced fluorescence chemistry, Celtarys custom-developed ligands offer both high affinity and exceptional selectivity across a wide range of GPCR targets. References Navarro G, Sotelo E, Raïch I, Loza MI, Brea J, Majellaro M. A Robust and Efficient FRET-Based Assay for Cannabinoid Receptor Ligands Discovery. Molecules. 2023 Dec 15;28(24):8107. doi: 10.3390/molecules28248107 Nørskov-Lauritsen L, Thomsen AR, Bräuner-Osborne H. G protein-coupled receptor signaling analysis using homogenous time-resolved Förster resonance energy transfer (HTRF®) technology. Int J Mol Sci. 2014 Feb 13;15(2):2554-72. doi: 10.3390/ijms15022554. Degorce F, Card A, Soh S, Trinquet E, Knapik GP, Xie B. HTRF: A technology tailored for drug discovery - a review of theoretical aspects and recent applications. Curr Chem Genomics. 2009 May 28;3:22-32. doi: 10.2174/1875397300903010022.

The blood-brain-barrier (BBB) and the complexity of the central nervous system (CNS) pose a challenge for developing successful therapeutics , particularly for neurological disorder and neurodegenerative diseases. This includes diseases such as depression, Parkinson’s, schizophrenia, and Alzheimer’s. GPCRs play a central role in neuronal signaling and have been used to treat these diseases with varying degrees of success. They mediate the effects of neurotransmitters and neuromodulators. The central role of GPCRs in Neurological Disorders GPCRs are the largest family of membrane receptors and participate in several CNS functions. Most of these are essential processes, such as neurotransmission, synaptic plasticity, mood, cognition, motor control and sensory perception. Thus, they also participate in numerous diseases. Over 30% of FDA-approved drugs target GPCRs, with many targeting CNS located GPCRs. Most of them are small molecules capable of going through the BBB , and since their targets are on the membrane of cells, they have easier access to the receptors than those that need to get into the cells to modulate intracellular signaling. One of the biggest hurdles is the understanding and correct targeting of the different receptor subtypes involved in each disease and the downstream and side effects attached to them. GPCR Structure, Activation, and Signaling Pathways in the Brain An understanding of GPCR structure is key in drug design. GPCRs posses a seven-transmembrane domain architecture, which lets them transduce extracellular signals into intracellular responses. They manage this by interacting with G-proteins. What happens when a GPCR is activated? When the endogenous binder of the GPCR (which can be a neuromodulator, neurotransmitter, etc.), binds to the extracellular binding site of the GPCR, the protein changes into its active conformation , which starts the intracellular signaling cascade. Depending on the type of GPCR, it can lead to different secondary messengers , like cAMP, IP3, which will ultimately modify gene expression, neurotransmitter release and plasticity. Figure 1. GPCR signaling: (A) an orthosteric ligand (orange) binds an inactive GPCR, the β2 adrenergic receptor (β2AR; PDB ID: 2RH1); (B) A ligand-bound GPCR undergoes a conformational change to its active state (PDB ID: 3SN6); and (C) an active GPCR binds a G protein (PDB ID: 3SN6), which subsequently promotes nucleotide release from, and activation of, the G protein α-subunit. Source: Latorraca NR, Venkatakrishnan AJ, Dror RO. GPCR Dynamics: Structures in Motion. Chem Rev. 2017 Jan 11;117(1):139-155. The activation of these pathways regulates pain modulation, memory consolidation, motor coordination etc. The concept of biased agonism must also be highlighted here. The conformation change induced by the agonist may not always lead to the same intracellular signaling . Some agonists induce conformations more adept at activating β-arrestins for example, leading to different intracellular effects. Studying these routes may reduce side-effects when using GPCR-based therapies. Emerging GPCR Therapeutic Targets in CNS Drug Discovery GPCRs have been studied for decades, but there are some, known as orphan GPCRs , which seem to be implicated in CNS pathologies but are not fully studied. Some of these are GPR6, GPR37 and GPR139 , which participate in motor control, neuroprotection and metabolic regulation. Their physiological ligands are not fully understood, which opens new treatment possibilities. GPR6 has been linked to neuroprotective functions and is now being investigated for its role in Parkinson’s disease and neuropathic pain. GPR37 has been linked to the Parkinson’s disease as well, though more focused on the progression of the disease. GPR139 is implicated in schizophrenia and ADHD. Figure 2. Orphan GPCRs related to neurodegenerative disorders. Source: Kim J, Choi C. Orphan GPCRs in Neurodegenerative Disorders: Integrating Structural Biology and Drug Discovery Approaches. Curr Issues Mol Biol. 2024 Oct 19;46(10):11646-11664. Of the traditional GPCRs, CBRs are gaining ground as potential therapeutic targets in several CNS diseases, such as Parkinson’s. As mentioned in previous posts, CELT-335, one of our fluorescent compounds, was successfully employed in a binding assay for CB1R and CB2R. More research into the endocannabinoid system (ECS) will let us access these GPCRs in a safer manner. Both orphan and well-characterized GPCRs are untapped opportunities for drug development targeting CNS diseases , especially as traditional targets seem to have stagnated when not focusing on biased-agonism. The newer generations of targets and screening tools will pave the way for safer and more efficient drugs. Advantages of Fluorescent Ligands in GPCR Drug Screening for CNS Choosing the right tools is important for the success of drug discovery, just as much as choosing the right targets. One of the best tools to study therapeutic targets are fluorescent ligands , which are very useful in GPCR drug discovery, starting from hit and lead validation all the way to pre-clinical assays. Some of the advantages of using fluorescent ligands for this are: Live-cell imaging:  receptor-ligand interactions can be visualized in real-time without fixating the cells. Greater specificity : allows for selective tracking of receptor subtypes in complex brain tissues. Reduced background noise: Improvements in signal-to-noise ratio are key in CNS assays. Faster assay development: also speeds GPCR target validation. Avoid safety concerns and regulatory hurdles: Non-radioactive alternative to screening In the context of CNS drug development, where receptor localization and real-time signaling are crucial , fluorescent ligands offer a powerful and adaptable solution. Their integration into drug discovery neuroscience workflows helps accelerate GPCR target identification, characterization, and lead optimization. References Latorraca NR, Venkatakrishnan AJ, Dror RO. GPCR Dynamics: Structures in Motion . Chem Rev. 2017 Jan 11;117(1):139-155. doi: 10.1021/acs.chemrev.6b00177 Alavi MS, Shamsizadeh A, Azhdari-Zarmehri H, Roohbakhsh A. Orphan G protein-coupled receptors: The role in CNS disorders . Biomed Pharmacother. 2018 Feb;98:222-232. doi: 10.1016/j.biopha.2017.12.056 Azam S, Haque ME, Jakaria M, Jo SH, Kim IS, Choi DK. G-Protein-Coupled Receptors in CNS: A Potential Therapeutic Target for Intervention in Neurodegenerative Disorders and Associated Cognitive Deficits . Cells. 2020 Feb 23;9(2):506. doi: 10.3390/cells9020506   Kim J, Choi C. Orphan GPCRs in Neurodegenerative Disorders: Integrating Structural Biology and Drug Discovery Approaches. Curr Issues Mol Biol. 2024 Oct 19;46(10):11646-11664. doi: 10.3390/cimb46100691   Navarro G, Sotelo E, Raïch I, Loza MI, Brea J, Majellaro M. A Robust and Efficient FRET-Based Assay for Cannabinoid Receptor Ligands Discovery. Molecules. 2023 Dec 15;28(24):8107. doi: 10.3390/molecules28248107

Innovative design approach emphasizing scientific principles over speculation. This Week’s GPCR Intelligence: From Set-Point Pharmacology to No-Wash Internalization Assays This week’s Dr. GPCR News delivers a toolkit of practical innovations—from drug design strategies that anticipate physiological resistance, to no-wash internalization detection tools, to HTRF ligand optimization techniques that reduce background noise and amplify weak signals. Whether you’re optimizing screening campaigns or navigating translational challenges, these insights give you a sharper edge. Premium Members rely on this intelligence weekly—and here’s your curated preview. Breakthroughs this week: Lilly to build $5B manufacturing facility in Virginia; Novo Nordisk flags drug trial promise; Nanobody sensor reveals β-arrestin conformational diversity. 🔍 This Week in Dr. GPCR Premium: Sneak Peek Want the full classified brief? Here’s what Premium Members accessed this week  across four critical domains: Industry insights:  Neurocrine at Morgan Stanley; Crinetics September inducement grants; fresh GPCR Q3 earnings forecasts; IIT Kanpur’s live-cell GPCR sensor. Upcoming events:  47th Symposium on Hormones & Cell Regulation; new approach to GPCR internalization analysis; “Soluble Proteins in Focus” for Cryo-EM prep; GPCR Forum Meeting 2025. Career opportunities:  Senior Scientist, Phage Display | Manager, CMC Management | Translational R&D openings Must-read publications:  New findings on structure-encoded location-biased signaling, GPCR signaling in metabolism, and future directions in biased ligand pharmacology. Terry's Corner – Designing Drugs That Anticipate Physiological Pushback Most GPCR programs don’t fail because the assay was flawed—but because in vivo counterregulation  neutralized the response. This week’s Terry’s Corner  exposes the unseen physiological “opponents” your molecule faces—and how to design around them. Avoid compensatory misreads:  Renin inhibition drops BP in normals, but not in heart failure—because cardiac output offsets the signal. Design smarter inotropes:  Dobutamine’s α-activity harnesses baroreflexes to increase contractility without runaway HR. Target protected agonism:  Internalized MT2 signaling escapes AGRP antagonism—unlike α-MSH. Unlock On-Demand Yearly Access Now — Premium Members Get Over 50% Discount at Checkout ➤ Revvity x Dr. GPCR: A Mission-Aligned Partnership That Advances the Field At Dr. GPCR , our mission is simple but urgent: Accelerate GPCR biology and drug discovery by connecting scientists with the knowledge, tools, and people that move the field forward. That’s why we partner with innovators like Revvity , whose new reagent family— pHSense™ —isn’t just another product. It’s a response to unmet scientific needs: Replace microscopy-heavy workflows with no-wash, live-cell TRF detection Empower high-throughput internalization studies, even at endogenous expression levels Offered in four flexible formats  that meet scientists where they are—Anti-FLAG, Anti-IgG, and SNAP-tag included This isn’t theoretical. As Dr. Eric Trinquet shares in a special Dr. GPCR Podcast, the Revvity team built pHSense™ from the ground up by listening to what GPCR scientists actually need—and validating it where it counts. 🎧 Go behind the scenes with Revvity —from the chemistry to the critical moments that changed everything. 👉 Discover the pHSense™ Reagents + Listen to the podcast ➤ Celtarys Research – Optimizing HTRF with Fluorescent Ligands Traditional ligand-binding approaches risk false positives and poor sensitivity—especially with weak or partial GPCR interactions. A new contributor article from our friends at Celtrays Research outlines how dual-labeled fluorescent ligands  solve this. Dual-label specificity blocks promiscuous ligand confusion Lanthanide donors + d2 acceptors = high SNR, low background Multiplex-compatible (e.g., IP1 + cAMP) for tracking biased agonism Read the full technical guide ➤ Why Dr. GPCR Premium Membership Gives You an Edge Premium delivers curated, noise-free intelligence every week:  deep-dive expert lectures, classified industry news, priority event alerts, job opportunities, and insider commentary—designed to help you move faster, smarter. No spam. No filler. Just the signals that move science. FAQ: Premium Membership 🔹 What’s included? The complete Weekly News digest, curated jobs, upcoming events, classified GPCR publications, on-demand expert frameworks, and member-only discounts. 🔹 Who is it for? GPCR scientists, translational pharmacologists, biotech discovery teams, and decision-makers who need fast, curated, career-relevant intelligence to stay ahead. 🔹 Why now? GPCR innovation is accelerating. Those acting on the right signals today will shape tomorrow’s breakthroughs—and avoid delays others won’t see coming. 👉 Already a Premium Member? Access this week’s full Premium Edition here ➤ What our members say "I am a convert! I will keep Dr. GPCR and the offered resources in my work sphere." — DrGPCR University Attendee GPCR innovation doesn’t wait. Neither should you. 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Drug pipelines live and die by your ability to make fast, accurate calls. One wrong assumption about how your molecule behaves in a living system can sink months of work and millions in development costs. The real challenge? GPCR signaling almost never follows a straight path. Reflex arcs, compensatory pathways, and receptor trafficking can turn your expected outcome on its head, sometimes after you’ve already committed to a clinical strategy. This session gives you the tools to anticipate those twists before they hit your program. This article is about one big idea: GPCRs don’t act in isolation—they respond to the system they’re in, often through opposing processes that you must model to get reproducible results. In this session, you’ll gain: ✅ A mental model you can trust  for predicting how GPCR ligands behave in real physiology—not just in a dish. ✅ A pattern-recognition toolkit  to spot red flags early and make course corrections before trials derail. ✅ Practical strategies  for using receptor trafficking data and system set-points to design cleaner, more predictive experiments. Why Pipeline Efficiency Starts with Physiology Drug discovery doesn’t happen in a vacuum. Every ligand you design enters a system that is already balancing opposing forces—vasoconstriction vs. vasodilation, sympathetic vs. parasympathetic tone, signal activation vs. receptor downregulation. Ignore these forces, and your “selective” agonist may deliver surprises the first time it meets a patient. This lecture challenges the habit of treating in vitro data as destiny. Instead, you’ll walk through cardiovascular reflexes, surface signaling vs. internalization, and constitutive receptor activity to show how the body bends your molecule’s effect. If your job is to move molecules confidently toward the clinic, this is a blueprint for building a more reliable evidence base—one that accounts for biology’s counterpunch. When In Vitro Lies: The Patient vs. Volunteer Gap Many programs die in Phase II, not because the molecule is “bad,” but because its profile in patients was never truly understood. A renin inhibitor that lowers blood pressure in healthy volunteers might not drop blood pressure at all in heart failure patients, because increased cardiac output cancels the expected effect. You’ll understand why this is good news, not bad data, and how it can actually prevent harmful reflex tachycardia. The bigger lesson? Context matters. This section outlines the logic required to match preclinical models to patient physiology and avoid being misled by early screens. Once you see how patient physiology flips expected outcomes, the next step is to ask, could these reflexes work in your favor? Reflexes as Drug Design Partners Not all reflexes are enemies. Some can make a mediocre drug shine. Dobutamine’s dual action on beta and alpha receptors, for example, invites reflex bradycardia that blunts its heart rate liability—making it a better inotrope than isoproterenol in heart failure. Learn how to view reflexes not just as confounders but as potential allies. The teaser question How could you design your next lead to recruit the body’s own feedback loops in your favor? Surface vs. Internalized Signaling: Same Receptor, Different Story A GPCR response isn’t always over when the receptor leaves the membrane. In this module, you’ll explore how some receptor–agonist complexes continue signaling from endosomes, creating “protected” signaling that extracellular antagonists can’t block. This insight has huge implications for how you select and rank agonists in discovery campaigns. You’ll come away asking Which of my ligands might be producing hidden signaling from inside the cell—and how can I measure it before it surprises me downstream? System-Dependent Activity and Opposing Processes Partial agonists don’t wear single labels. The same compound can look like an activator in one system and a blocker in another—depending on basal tone. Terry illustrates this with classic β-receptor partial agonists, showing how heart rate set-points under different anesthetics can flip observed pharmacology. The takeaway? When you evaluate partial agonists, enzyme inhibitors, or antagonists, you must recreate the “working system” they’ll face in vivo—otherwise you risk throwing out molecules that would have worked. Constitutive Activity: When Doing Nothing Still Does Something Some GPCRs simply refuse to stay quiet. Ghrelin receptors, for example, signal spontaneously, meaning a neutral antagonist won’t suppress appetite; it just blocks added stimulation. Get a sense of why inverse agonists may be necessary to truly shift the physiological balance. This section raises a critical design question for teams Are you sure your “antagonist” is enough—or do you need an inverse agonist to get the clinical outcome you want? Your molecule isn’t failing—your model might be too simple. Terry’s Corner exists to fix that blind spot. Subscribe today and get direct access to decades of pharmacology experience that turn complex systems into better decisions. Why Terry’s Corner Most pharmacology training freezes at equilibrium snapshots. But drug discovery isn’t static — it’s a moving target. Ligands come and go, feedback loops kick in, and what you see in vitro rarely tells the whole story. Go inside the real-world playbook. Here’s what you’ll get: Weekly expert sessions  that turn messy data into clear decisions On-demand access  to a growing library of system-level case studies Unfiltered Q&A recordings  where challenging problems get solved live Direct input opportunities  so future sessions answer your  questions Battle-tested insight  from four decades of drug discovery experience If you’re serious about derisking your pipeline, this is where you sharpen the tools that actually move molecules forward. See beyond the equilibrium. Make decisions with confidence. 🟢 40 years of expertise at your fingertips: Explore the complete library ➤ ✳️ Want to know what’s inside? Read the latest articles ➤ Stay sharp between lectures. Subscribe to The Kenakin Brief today ➤

Discover how Revvity’s pHSense™ reagents enable real-time GPCR internalization detection A breakthrough GPCR internalization assay now featured in the Dr. GPCR Ecosystem Boston, MA – September 2025  — Dr. GPCR , the global nonprofit platform dedicated to advancing GPCR science through education, community, and platform visibility , is proud to spotlight pHSense™ , a new reagent family from Revvity , now featured across the Dr. GPCR Ecosystem. Developed to address long-standing challenges in GPCR internalization assays , pHSense™ reagents  combine live-cell, no-wash protocols  with time-resolved fluorescence (TRF) detection , enabling real-time detection of GPCR internalization —without microscopy. “The day we saw dose-dependent internalization in endogenous GLP1R cells—without microscopy—that was the turning point,” said Dr. Eric Trinquet, Director of Research and Development at Revvity.   A GPCR Internalization Tool Designed for Real Research Needs Built on more than two decade A GPCR Internalization Tool Designed for Real Research Needs s of GPCR assay innovation , pHSense™  was developed to overcome three persistent barriers in internalization studies : Complex imaging workflows Limited scalability for high-throughput screening Low sensitivity in detecting endogenous GPCRs With pHSense™, scientists can finally track GPCR internalization  in real time—even at physiological expression levels —using a simple plate-based format . The reagents are compatible with HTRF readers  and validated in GLP1R  and Mu opioid receptor (MOR)  models. Part of a Complete GPCR Reagent Portfolio pHSense™ is the latest addition to Revvity’s GPCR reagent portfolio , which supports every stage of the signaling cascade: GPCR ligand binding  – TR-FRET, radioligand, Tag-lite® G-protein activation  – cAMP, IP-One, GTP assays β-arrestin recruitment assays Downstream readouts  – phospho-ERK, AKT, CREB, MEK and other phoshoproteins These reagents are optimized for high-throughput GPCR screening , reproducibility, and translational depth. 👉 Explore Revvity’s Full GPCR Reagent Catalog 🎙️ Hear More About pHSense™ on the Dr. GPCR Podcast To mark the spotlight, Dr. GPCR  invited Dr. Eric Trinquet  to the Dr. GPCR Podcast , where he shares the story behind pHSense , including its application in real-time internalization assays  and the scientific “aha” moments that drove its development. “This isn’t just another product,” said Dr. Yamina Berchiche, Founder of Dr. GPCR. “It’s a leap forward in how the community studies GPCRs at scale and in context.” 🔗 About Dr. GPCR Dr. GPCR  is a global nonprofit platform advancing GPCR research  through education, community, and platform visibility. Through our podcast, training programs, and partner content, we help scientists connect, collaborate, and innovate in the world of G protein-coupled receptors . 🔗 About Revvity Revvity  is a global life sciences company delivering translational tools and diagnostics. Its GPCR research tools  support discovery teams and academic labs with precision reagents and validated assay platforms. 🔍 Learn More → Listen to the Podcast with Revvity’s Eric Trinquet → Explore the pHSense™ Reagent Line → Browse Revvity’s GPCR Assay Portfolio

Exploring the Hidden Dynamics: How Kinetics Reveals What Equilibrium Conceals in GPCR Research. Hi GPCR Community, If equilibrium curves are your comfort zone, this week’s feature will challenge (and strengthen) your decisions. We’re zeroing in on kinetic tools that reveal what steady-state data can’t—so you can vet leads faster, avoid false positives, and move with confidence. That’s precisely what Terry’s Corner delivers each week: practical frameworks from Dr. Terry Kenakin to elevate your science and sharpen your calls. Breakthroughs this week:  Septerna begins first-in-human trial of SEP-631 for CSU; Maxion’s KnotBody® platform; a new angle on RGS protein modulation. 🔍 This Week in Dr. GPCR Premium: Sneak Peek Here’s a fast, high-level preview of what Premium Members are unpacking this week. It’s a curated lens—just enough signal to guide your week, with the full depth available inside. Industry insights:  Orforglipron’s trajectory is redefining weight-management and diabetes markets—implications for GPCR-linked pathways and competitive positioning. Upcoming events:   Preview of Discovery on Target 2025 (Boston, Sept 24‑25), including GPCR‑Track breakout sessions; panel opportunities to engage with biophysics and structural biology leaders. Career opportunities:  Snapshot of roles spanning PhD entry points to senior translational pharmacology—Protein Expression, Drug Discovery Scientist, and Staff Scientist in Molecular Pharmacology—curated with notes on fit, skill spikes, and timelines. Must-read publications:  From on stabilizing RGS2 via modulating its degradation (versus direct inhibition); selectivity frameworks for β₂ vs β₁ adrenergic receptors tp structural insights into cholesterol interactions in the active conformation of GLP‑1 receptor Terry's Corner – Advanced Applications of GPCR Kinetics for Real-World Decision Making Equilibrium looks tidy. But kinetics tells the truth. This week, you will learn how to confirm equilibrium the right way, detect time-dependent occupancy and complex activity, leverage hemi-equilibrium calcium assays, recognize fractal potency, and surface liabilities early—before they cost you cycles and credibility. These are the pattern-recognition tools that convert uncertainty into decisions you can defend at a project review. Avoid expensive mirages:  Spot when “good” equilibrium curves mask time-dependent binding that will fail in translational settings. Protect your screening funnel:  Use hemi-equilibrium readouts to flag artifacts before they inflate your SAR. Out-decide your competition:  Apply fractal potency insights to prioritize leads that stay robust across conditions. Premium Members get a 50%+ discount when they join Terry’s Corner. 🚨 Live AMA with Dr. Kenakin is today, September 18th, 12-1 pm EST in Terry’s Corner. Corner members get to rewatch the recording Subscribe to the Kenakin Brief and Join the Live AMA ➤ Celtarys Research – Flow Cytometry Reimagined: Fluorescent Ligands vs Antibodies for Live‑Cell GPCR Studies Traditional antibody staining for GPCRs has well‑known limitations—fixation artifacts, epitope masking, low expression, conformation changes.  Fluorescent small-molecule ligands flip the script: direct binding to functional sites, live-cell compatibility, and higher specificity enable real-time tracking of interactions, internalization, and biased signaling—without fixation or permeabilization. Learn how to choose fluorophores (brightness, stability, spectra), reduce background (far-red/near-IR), and match channels to your cytometer for clean, multiparametric data. Eliminate fix/perm distortions:  Preserve receptor conformation and downstream signaling integrity. Get functional—not just presence—readouts:  Quantify affinity and kinetics where it matters. Scale confidently:  Use bright, stable ligands for HTS and bias profiling. See the full guide and example ligands ➤ Discovery on Target 2025 Speaker Spotlight: Solubilization, Orphans & Lipid Systems In a conversation with Alison Heick Varghese and Kris Borzilleri (Pfizer), we dig into detergent-free, lipid-mimic systems for reliable GPCR screening; orphan GPCR strategies; and advances across nanodiscs, peptidiscs, SMALPs, SPR, ITC—plus how construct design and solubilization choices shape success. In Boston, Sept 24–25? We’ve got your GPCR Track, Happy Hour, and sessions mapped so you can extract maximum value. Register now and save with code SPK200 ➤ Why Dr. GPCR Premium Membership Gives You an Edge Premium delivers curated, noise-free intelligence every week: expert frameworks  (like Terry’s Corner), classified industry news , priority event alerts , targeted job leads , and editorial guidance  that turns information into action. It’s built for the GPCR community—by people who live the science—so you spend less time sifting and more time deciding. If you need to brief leadership, plan experiments, or time a move in the market or your career, Premium makes sure you’re working from the clearest signal available. FAQ: Premium Membership 🔹 What’s included? The complete Weekly News digest, curated jobs and upcoming events, must-read GPCR publications, exclusive on-demand expert frameworks, and member-only discounts. 🔹 Who is it for? GPCR scientists, translational pharmacologists, biotech discovery teams, and decision-makers who need fast, curated, career-relevant intelligence to stay ahead. 🔹 Why now? GPCR innovation is accelerating. Those acting on the right signals today will shape tomorrow’s breakthroughs—and avoid delays others won’t see coming. 👉 Don’t Fall Behind—Access the Edge You Need 👉 Already a Premium Member? Access this week’s full Premium Edition here ➤ What our members say "Dr. Kenakin is a leading expert in the field. Aside from his vast experience in drug development, not to mention his extensive publication record, Dr. Kenakin is a masterful teacher and communicator." — DrGPCR University Attendee Everything you need to master GPCR science — in one membership. 🎓 Full GPCR University + 🔬 200+ expert talks 🗞️ Weekly research, careers & event intelligence 🤝 Members-only networking, AMAs & matchmaking 💡 Support open resources for the global GPCR field 🧠 Designed for researchers at every career stage Don’t just keep up — lead the way 🚀 Join Premium Today ➤

Join Dr. GPCR and global experts at the GPCR Drug Discovery session during Discovery on Target 2025—where groundbreaking collaborations begin. GPCR Drug Discovery at Discovery on Target 2025 — The Track You Can’t Miss If you work in drug discovery  or biotech , this is your moment. Mark your calendar, it's happening September 22-25, 2025. From obesity and diabetes to cancer, fibrosis, and CNS disorders — GPCRs  are at the heart of the world’s most pressing therapeutic challenges. And at this year’s Discovery on Target  meeting in Boston, the GPCR Drug Discovery track will deliver breakthroughs, bold ideas, and the strategies shaping the next wave of medicines . I’m honored to be chairing a session  in this track — with none other than Terry Kenakin  on the speaker lineup. 🌟 Speaker Spotlight In the run-up to the conference, our founder Yamina Berchiche is speaking with some of the brilliant minds presenting in the GPCR track. Here’s who we've talked to so far: 🎥 Check out the interview with Dr. Aaron McGrath from Takeda   🎥 Interview with Kris Borzilleri & Alison Heick Varghese from Pfizer 🎥 Interview with Terry Kenakin from UNC and Terry's Corner We'll continue to update this section as new videos are released — so check back before the meeting for fresh insights and behind-the-scenes perspectives from our speakers. 🌐 Why Dr. GPCR Is in This Conversation At Dr. GPCR , our mission is simple: connect the GPCR community, share knowledge, and accelerate innovation . At Yamina's Corner , our founder Yamina Berchiche works closely with organizations to help them navigate receptor pharmacology, identify opportunities, and move their programs forward effectively. Over the years, we’ve built a global network of researchers, biotech leaders, and pharma innovators who believe that GPCR science is one of the most powerful tools we have to address urgent health challenges. Chairing this session isn’t just another speaking engagement — it’s an extension of what we do every day: Spotlight innovation  across academia and industry. Foster collaboration  through our platform and events. Push the boundaries  of receptor pharmacology and its real-world applications. When we step into the GPCR track at Discovery on Target, we’re not just participating. We’re helping shape the conversation. 🚀 Why GPCRs Are Still the Hottest Target Class in Drug Discovery GPCRs regulate countless physiological processes, making them a goldmine for therapeutic breakthroughs. They’re already behind blockbuster drugs: GLP-1 receptor agonists  – reshaping obesity & type 2 diabetes care. CCR5 antagonists  – fighting HIV and certain cancers. Dopamine D2 receptor modulators  – transforming treatment for Parkinson’s & schizophrenia. PAR1 antagonists  – protecting cardiovascular health. But the real  excitement is in what’s next: Biased signaling  for selective therapeutic effects. Allosteric modulation  for unprecedented precision. Structure-based design  powered by cryo-EM and AI. 🔬 Inside the GPCR Track Agenda Expect deep dives into: CXCR4  in oncology and immune regulation. GIPR/GLP-1R co-agonists  in metabolic diseases. Serotonin & dopamine receptor modulation  for neuropsychiatric disorders. Orphan GPCRs  with untapped therapeutic potential. These sessions bridge structural biology , computational modeling , and clinical translation  — with tangible takeaways for programs from discovery through late-stage development. 🗝️  Highlight: Terry Kenakin at Discovery on Target Terry Kenakin’s work on functional selectivity  has transformed GPCR drug discovery, showing how to bias receptor signaling toward beneficial outcomes and away from side effects. Hearing Terry speak is more than an academic experience — it’s like being handed a new set of tools to rethink your drug design strategy. Having him in the session I’m chairing is not just an honor — it’s a highlight of the year.   📚 Terry’s Corner — The Only On-Demand Pharmacology Hub with Dr. Kenakin Himself If you’re part of the Dr. GPCR  community, you already know about Terry’s Corner  — our exclusive, on-demand pharmacology series where Terry Kenakin breaks down receptor pharmacology, functional selectivity, and ligand bias in a way you can apply directly to your work. It’s the only  resource of its kind — part masterclass, part fireside chat — available anytime to our members. For those who can’t get enough of Terry’s insights at Discovery on Target, Terry’s Corner  keeps the learning going long after the conference ends. 💡 Why This Matters — Even If You’re Not a GPCR Scientist GPCR pathways intersect with oncology, CNS, metabolic, cardiovascular, immunology, and fibrosis research . Whether you’re in early discovery or clinical development, the strategies here could open doors in your own therapeutic area. 🧭  Join Us in Boston 🗓 Discovery on Target  — Boston, MA 📅 September 23-25, 2025 🎯 Track:   GPCR Drug Discovery Let’s connect. Let’s debate. Let’s move GPCR drug discovery forward — together. 🚨 Mark your calendar for the GPCR Happy Hour Join us at GPCR Happy Hour , where scientists, biotech leaders, CRO professionals, and investors from around the globe meet Boston’s vibrant life sciences hub. ✨ Spark collaborations. ✨ Strengthen the GPCR community. ✨ Be part of Dr. GPCR’s nonprofit mission to connect and empower the global GPCR ecosystem. 📅 September 24, 2025 📍 Pressed Café, Huntington Ave, Boston ⏰ 6–8 PM EST ⚠️ Space is limited — Secure your spot now

If you’ve ever trusted a Ki value without asking how  it was measured, you’ve already stepped into the trap. In drug discovery, equilibrium constants look tidy. But biology isn’t tidy. Onset and offset rates (not just “final numbers”) decide which drugs succeed in patients and which ones die in development. Affinity snapshots alone won’t save your pipeline. Kinetics will. This session gives you precisely that. By the end, you’ll know how to confirm true equilibria, detect hidden drug activities, and separate safe candidates from toxic ones long before clinic. No more blind spots, only decisions rooted in reality. In this session, you'll gain: ✅ Tools to confirm true equilibrium and avoid potency errors from premature reads ✅ Methods to detect hidden mechanisms—mixtures, dual effects, or time-dependent inhibition—through curve shapes and kinetics ✅ A framework to classify antagonists and rank compounds by offset rate, using rapid calcium assays Potency Is a Ratio of Rates Two ligands compete for the same receptor. Which wins? Not just the one with higher affinity, but the one that gets there faster and leaves slower. Think of it like catching a train: two passengers have tickets (affinity), but only the one who sprints to the platform on time (fast onset) and stays seated (slow offset) actually gets the ride. Ignore this, and you’ll misrank compounds. Respect it, and you’ll see why drugs with identical Ki values diverge in vivo. This is the first trap: assuming equilibrium when you haven’t reached it.  Curves that “look fine” may hide non-equilibrated systems. The fix? Use curve shapes as diagnostics: flattened, biphasic, or lagging responses aren’t noise. They’re telling you to wait. When Equilibrium Lies Sometimes, numbers don’t add up. You calculate an equilibrium value that requires a physically impossible onset rate. That’s your signal: kinetics are moving faster than your tools can measure. It’s like calculating a runner’s pace and realizing they’d have to break the sound barrier to make the numbers work. The math itself is your clue that something else is happening. This is the second trap: trusting impossible math. If you ignore it, you risk false certainty. If you detect it, you gain texture that equilibrium constants alone can’t provide. And this texture matters; kinetics have separated safe dopamine antagonists from those with extrapyramidal side effects. Hidden Mixtures, Hidden Risks Peptides degrade. Drugs carry dual mechanisms. At equilibrium, these effects cancel. But kinetics unmasks them. Instead of clean monophasic curves, you’ll see biphasic signatures or sequential shifts—first cholinesterase inhibition, then receptor blockade. This is the third trap: assuming one mechanism when two are in play. Catch it early, and you avoid wasting months chasing the wrong SAR. The Hemi-Equilibrium Problem Calcium assays look simple. But if your antagonist has a slow offset, you’ll see depressed maximal responses that equilibrium theory can’t explain. This is the fourth trap: classifying antagonists as weak when they’re just slow. Flip it around, and you’ve got a shortcut: use depression of max in calcium assays to rapidly rank offset rates, and predict in vivo coverage before you ever dose an animal. Fractal Potency: The Illusion of Nothing, Then Everything Measure too soon, and low concentrations look inert. Suddenly, at higher doses, you see an exaggerated ‘bang’ of effect. It’s like waiting for popcorn: at first, nothing happens, then suddenly the bag explodes with pops. But that’s timing, not a different kind of corn. That’s not pharmacology. That’s kinetics. This is the fifth trap: misclassifying your antagonist because you didn’t wait. The cure is simple: extend equilibration. Once you do, the irregular potency vanishes, and the true profile emerges. What You’ll Walk Away With By the end of this session, you won’t just “know about kinetics.” You’ll know how to use  kinetics to sharpen decisions: Confirm whether your system has truly equilibrated Detect hidden activities before they waste resources Classify antagonists by offset rate without waiting on PK data Spot time-dependent inhibition that signals toxic liabilities Avoid being fooled by fractal potency artifacts This isn’t academic nuance. It’s the difference between building a solid pipeline and chasing ghosts. Kinetics in Drug Discovery: Your Edge If you’re still treating potency as a static number, you’re missing half the story. Kinetics turns confusion into clarity, reveals risks earlier, and helps you rank compounds by the criteria that matter most in patients. This isn’t just another lecture. It’s a shift in how expert drug hunters see pharmacology. And once you see it, you’ll never go back. Unlock “Kinetics: Advanced Applications” Only in Terry’s Corner Why Terry’s Corner Most pharmacology training stops at equilibrium values. But discovery doesn’t. The reality is dynamic—ligands arrive, depart, and interact in ways that standard assays often miss. That’s where Terry’s Corner changes the game. Here, you’ll find: Weekly lectures  that sharpen the tools you actually use in discovery A growing on-demand library  of lessons you can revisit whenever you need them Exclusive access  to the next AMA session Direct engagement opportunities  through AMAs and topic suggestions Practical insights  distilled from decades of pharmacology experience Whether you’re validating assays, refining kinetic models, or deciding which leads to advance, Terry’s Corner gives you the frameworks to detect hidden liabilities and uncover real drug potential. See beyond the equilibrium. Make decisions with confidence. 🟢 40 years of expertise at your fingertips: Explore the complete library ➤ ✳️ Want to know what’s inside? Read the latest articles ➤ Stay sharp between lectures. Subscribe to The Kenakin Brief  today ➤

Fluorescent probes illuminate the mysteries of GPCRs in cutting-edge research. Hi GPCR Community, If you work on GPCR discovery, you already know: early signals can mislead, and timing your next decision is career-critical. This week, we focus on how to convert ambiguous data into confident, defensible Mechanism of Action calls—before resources drift. That’s precisely what Terry’s Corner delivers every week: practical tools from Dr. Terry Kenakin to elevate your science and sharpen your decisions. Breakthroughs this week:  5-MeO-DMT: the "God Molecule"; Novo Nordisk looks to next generation of obesity, diabetes drugs with $550M Replicate research deal; Rhythm Pharmaceuticals Announces FDA Acceptance of sNDA for Setmelanotide in Acquired Hypothalamic Obesity. 🔍 This Week in Dr. GPCR Premium: Sneak Peek A fast, editorial preview—enough to guide your attention, not replace your due diligence. Industry insights:  Biopharma returns to MC4R; Recursion completes Exscientia acquisition, signaling a fresh AI–GPCR chapter; OMass–Genentech deal in IBD. Upcoming events:  “Drug Discovery at Superluminal Speeds”; and Discovery on Target 2025—GPCR track you’ll want on the calendar. Career opportunities:  Research Assistant; Postdoctoral Associate; Senior Scientist, Data Science—curated roles aligned to GPCR discovery and translational pharmacology. Must-read publications:  β-arrestin2-biased allosteric modulator for pain beyond opioids & GPR3 regulated by a negative allosteric modulator Terry's Corner – Determine GPCR MoA Early (and Right) Early discovery often serves you overlapping curves and noisy baselines; different mechanisms can masquerade as the same “effect.” This week’s Terry’s Corner lesson shows how to replace inference with models that disentangle mechanism—so your next go/no-go, dose range, and assay design are anchored in prediction, not intuition. You’ll apply a model-first workflow to classify orthosteric vs. allosteric behavior, stress-test assumptions through fit→predict→test loops, and improve SAR by separating affinity from efficacy. What you’ll gain—immediately relevant to your pipeline: Stop costly misreads:  Distinguish orthosteric vs. allosteric effects by extending predictions, not eyeballing plots—so you don’t advance a “hit” that collapses in validation. Engineer assays on purpose:  Set ranges, controls, and system sensitivity to surface mechanism—before you lock in a screen that hides the signal you need. Unlock real SAR:  Deconvolute potency into affinity vs. efficacy to make medicinal chemistry cycles more informative—and faster. Premium Members get a 50%+ discount when they join Terry’s Corner. 🚨 First-ever Live AMA with Dr. Kenakin  is happening September 18th, 12- 1 pm EST —exclusively inside Terry’s Corner. Bring the curve you’re debating. Ask. Challenge. Get an answer you can defend. Join Terry's Corner Today ➤ Celtarys Research – Confocal Imaging That Preserves GPCR Function Confocal imaging can clarify GPCR localization, trafficking, and dynamics—if your probes preserve function, minimize phototoxicity, and work in both live and fixed contexts. This applied article walks through ligand-directed labeling, SNAP/Halo tags, and fluorescent ligands tied to pharmacophores—plus how to choose probes for your biological context and temporal resolution. Expect practical guidance on TR-FRET compatibility, photobleaching resistance, and 3D stack acquisition for tissue-like environments. Why it matters now: Cleaner signal:  Selective excitation + low background reduces false positives in trafficking and clustering studies. Physiological relevance:  Fluorescent ligands can retain receptor integrity—critical when signaling readouts drive decisions. Assay flexibility:  Combine self-labeling tags with quantitative readouts (e.g., TR-FRET) to expand mechanism insight. Read the article here ➤ Discovery on Target 2025 – GPCR Speaker Spotlight DOT 2025 (Sept 22–25, Boston) is set to be a high-signal GPCR forum—bridging biased signaling, allostery, and structure-guided design across oncology, metabolic, CNS, and fibrosis programs. This week, get to know Dr. Aaron McGrath from Takeda. He joins Dr. Yamina Berchiche to discuss: 🔹 Why PAR1 and PAR2 are such unique GPCRs 🔹 What structural biology is teaching us about shallow orthosteric pockets and druggability 🔹 The role of cryo-EM in capturing fully activated GPCR complexes 📅 Catch Aaron’s full talk at Discovery on Target, Sept 24–25 in Boston. 🎥 Plus, join us at the GPCR Track, GPCR Happy Hour, and more! Register now and save with code SPK200 ➤ Why Dr. GPCR Premium Membership Gives You an Edge Premium delivers curated, noise-free intelligence every week: deep-dive expert lectures, classified industry news, priority event alerts, vetted job opportunities, and insider commentary—structured to help you move faster and make cleaner decisions. It’s built for scientists and leaders who want the signal, not the scroll: frameworks that clarify mechanism, context that sharpens strategy, and a community that accelerates collaboration. FAQ: Premium Membership 🔹 What’s included? The complete Weekly News digest, curated jobs, upcoming events, classified GPCR publications, and member-only discounts. 🔹 Who is it for? GPCR scientists, translational pharmacologists, biotech discovery teams, platform company leaders, and decision-makers who need fast, curated, career-relevant intelligence to stay ahead. 🔹 Why now? GPCR innovation is accelerating. 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Flow cytometry, a laser-based method, is used to examine single cells suspended in a fluid. By measuring the way these cells scatter light and emit fluorescence, they can be identified, quantified and isolated into distinct cell populations. Antibody staining is a technique that helps differentiate cells and has been used in flow cytometry for a long time. In order to expand its role in GPCRs, which antibodies tend to have more trouble binding to. Fluorescent ligands based on small molecules bind to the functional sites of receptors in live cells, no need for cell fixation or permeabilization. This facilitates the study of receptor dynamics, ligand binding and signaling in real time. Figure 1.  Schematic representation of the flow cytometry technique. Adapted from Drescher H, Weiskirchen S, Weiskirchen R. Flow Cytometry: A Blessing and a Curse. Biomedicines. 2021 Nov 4;9(11):1613.   Using Fluorescent Ligands Over Antibodies in Flow Cytometry Assays: Key Advantages These are key limitations of antibody staining in flow cytometry: 1.       No need for fixation and permeabilization This step can modify receptor conformation and affect downstream signaling. 2.       Antibody batch-to-batch differences Antibodies from different lots may show different characteristics. 3.       Specificity issues Some antibodies bind to shared epitopes across different proteins, which may lead to nonspecific staining. These limitations can impact data quality, reproducibility, and assay flexibility. Fluorescent ligands  provide some key advantages  that may solve these issues: 1.       Direct binding to functional sites They bind to the active site of the receptor, which also proves kinetic and binding affinity information, not just presence. 2.       Compatibility with live cells No need for fixation of permeabilization. Ideal for live cell low cytometry, which means you can monitor while preserving cellular integrity. 3.       Higher specificity and reproducibility Well characterized ligands show consistent and selective binding to their target, lowering background noise. How Fluorescent Ligands Transform Flow Cytometry in GPCR Analysis GPCRs are a tough target in traditional antibody staining due to their membrane localization, low expression and complex conformations. Using the advantages enumerated previously, fluorescent ligands provide new capabilities: -            Real time tracking they allow continuous observation of GPCR interactions and following internalization and recycling upon activation. -            High-throughput applications Bright and stable fluorescent ligands can be used in HTS, fast tracking the assessment of GPCR interactions and signaling pathways. -            Biased signaling detection Biased pharmacophores may be used in conjunction with fluorescent tags to study biased signaling pathways, improving our understanding of GPCR functional diversity and their therapeutic potential. These capabilities help with the quantification of functional receptor expression, following internalization, analyzing ligand-receptor interactions, which are not as detectable with antibodies. Innovations in the fluorophore tags, such as pH sensitive probes, can further improve signal-to-noise ratio and reduce background interference. Optimizing Fluorescence Channels and Fluorophore Selection for GPCR-Targeted Flow Cytometry The fluorophore tag is a key part of the flow cytometry assay, as there are several key factors to be considered: 1.       Tag brightness and stability:  the brighter and more stable the better the assay outcome. 2.       Emission spectra and overlap : cell autofluorescence is usually found in the green region of the emission spectra, so using distinct fluorophores closer to red simplifies the process. 3.       Autofluorescence and multiplexing: Using far-red or near-infrared fluorophores can reduce background and support multi-parametric assays. 4.       Instrument compatibility: Fluorophores should match the laser and detector configurations of the cytometer. The optimization of fluorescence channels  is also important. The compatibility of fluorophore and detector is key to ensure a clean signal. Innovations such as spectral flow cytometry and fluorescence lifetime imaging also expand the capabilities of these tags. Fluorescent ligands are an advancement for flow cytometry applications in the GPCR field, as they overcome many limitations of the antibody-based methods. At Celtarys, we support this transition by offering optimized fluorescent ligands specifically designed for GPCR targets , including CELT-240 for hD2/D3 dopamine receptors and CELT-483 for the hσ1/σ2 sigma receptor. In addition, we provide detailed protocols and expert guidance to help you achieve reliable, actionable flow cytometry results.  Figure 2 . CELT-240 in flow cytometry binding assays is suitable to measure the affinity of compounds for the D2/D3 receptors. Flow Cytometry validation performed in the Oncological Pharmacology Laboratory of the University of Turin.    References Drescher H, Weiskirchen S, Weiskirchen R. Flow Cytometry: A Blessing and a Curse. Biomedicines. 2021 Nov 4;9(11):1613. doi: 10.3390/biomedicines9111613 University of Virginia Flow Cytometry Facility. Critical Aspects of Staining Cells [Internet]. Charlottesville (VA): University of Virginia; [cited 2025 May 16]. Available from: https://med.virginia.edu/flow-cytometry-facility/wp-content/uploads/sites/170/2015/10/Critical-Aspects-of-Staining-Cells.pdf Böhme I, Beck-Sickinger AG. Illuminating the life of GPCRs. Cell Commun Signal. 2009 Jul 14;7:16. doi: 10.1186/1478-811X-7-16  Siddiqui S, Livák F. Principles of Advanced Flow Cytometry: A Practical Guide. Methods Mol Biol. 2023;2580:89-114. doi: 10.1007/978-1-0716-2740-2_5

If you’ve ever stared at a dose–response curve and wondered, “Is this partial agonism? Or something allosteric?” —you already know the trap. In discovery, different pathways may look identical at first glance. This week in Terry's Corner you'll learn how model-based thinking helps you determine a drug’s mechanism of action and turn assay snapshots into real predictions. And here’s the danger: if you can’t tell how  a drug is working, every downstream decision—SAR, lead optimization, even clinical strategy—rests on shaky ground. You don’t need more data—you need a way to translate snapshots into predictions. This session gives you exactly that. By the end, you’ll know how to use pharmacological models to separate lookalikes, explain puzzling outcomes, and make predictions that guide discovery forward, not sideways. In This Session, You’ll Gain: ✅ How to turn descriptive snapshots into predictive insights ✅ Tools to distinguish orthosteric vs. allosteric mechanisms ✅ A framework for using models to design better experiments From Observation to Prediction You’ve run your experiment. A compound shifts the curve. It elevates the baseline. But what does that really mean? The first trap in discovery is stopping at description. You can say what the drug “seems” to do, but not what it will do elsewhere. Models are the bridge. They take descriptive data from one system and translate it into parameters that can be applied to others. Suddenly, your snapshot becomes a forecast . Instead of saying, “This looks like partial agonism” , you can ask: What happens if concentration increases further? What happens when receptor expression is different? What happens in vivo? With a model, you don’t guess. You project. When Two Mechanisms Look the Same Some of the most difficult calls in pharmacology happen when two different mechanisms look identical in a single assay . Without the right model, it’s like staring at identical twins—you can’t tell them apart until you see them move. Take the example Terry highlights: an agonist curve with a rightward shift and elevated baseline. That could be: An orthosteric partial agonist , or An allosteric partial agonist The raw data won’t tell you which. But the model will . Extend the concentration range, and the predictions diverge: Orthosteric? The shift continues linearly. Allosteric? The shift plateaus once the allosteric site saturates. With the right model, you can separate lookalikes and prevent an entire program from being misclassified. When Binding Increases Instead of Decreases Another trap: paradoxical results. You add a non-radioactive analog of a ligand, expecting it to displace binding. Instead, binding increases. Without a framework, this looks like an assay error. With a model, it becomes explainable: if the dimer form has higher affinity, then adding ligand actually drives up bound species. This isn’t noise. It’s signal—once the model interprets it. Models as Experimental Guides Models don’t just interpret results. They design experiments. In HIV entry studies, purified gp120 was too expensive for routine assays. The question was: could crude gp120 supernatant be used instead, without corrupting results? A model answered: yes—provided CD4 concentrations stayed low and gp120 concentrations high. The outcome? Reliable results at a fraction of the cost. When data alone are ambiguous, models tell you which parameters to control, which conditions to vary, and where to focus your resources. Think of models as your GPS—they don’t just explain where you are, they guide you to the next best turn. Are Models Ever Proven? Here’s the uncomfortable truth: you can never prove a model “right.” But you can build confidence through iteration. The cycle is simple: Experiment → Model → Prediction → Experiment. Each loop tightens the fit. Internal checks (like requiring a Schild regression slope of unity for competitive antagonism) add further discipline. The goal isn’t perfection. The goal is reliability : enough confidence in the model to make predictions that hold across systems. Garbage In, Garbage Out Even the best models can only work with the data they’re fed. Poor-quality data in means poor-quality predictions out. Potency (EC₅₀) is a prime example. It’s a ratio of affinity and efficacy. If you stop at potency, structure–activity relationships (SARs) may look flat. But if you deconvolute into affinity and efficacy, a rich SAR emerges. Chemists suddenly have meaningful levers to pull. The lesson: models don’t just need data. They need the right data . A Case That Seemed Impossible In one real program, a compound produced four completely different assay signatures depending on the system: Sometimes it shifted curves left Sometimes it raised baseline activity Sometimes it boosted the maximum response Chemists were left asking: Which effect should we believe? Only when the data were fit to the right model did the picture snap into focus. What looked like four conflicting behaviors turned out to be one coherent mechanism , hidden in plain sight. That’s the power of model-driven thinking—it takes chaos and reveals consistency. What You’ll Walk Away With By the end of this session, you won’t just “know about models.” You’ll know how to use them to sharpen discovery decisions. Specifically, you’ll be able to: Convert descriptive assay snapshots into predictive insights Differentiate orthosteric vs. allosteric mechanisms with confidence Apply models to design cost-efficient, informative experiments This is more than learning concepts. It’s learning how to design, interpret, and decide with models built in . Determining Mechanism of Action: Your Edge If you’re still relying on descriptive observations—“looks like a shift,” “seems like baseline activation”—you’re leaving risk on the table. With the right models, you’ll know (not guess) how your drug works, how it differs from others, and how it will behave across systems. This isn’t just another lecture. It’s a shift in how you approach discovery. Model-driven discovery accelerates timelines, prevents misclassifications, and gives your team sharper levers to pull. That’s your competitive edge. Unlock “Mechanism of Action” now Only in Terry’s Corner   Why Terry’s Corner When early choices determine which programs advance, you can’t afford vague models or slow learning. Terry’s Corner is designed to give you the edge. Join for: Weekly, faculty-grade lessons that sharpen techniques you actually deploy A continuously expanding, searchable on-demand library Monthly Ask-Me-Anything sessions  (first one coming in the next few weeks!) Subscriber-driven topics,  so the next lesson addresses your bottleneck. Built for discovery-phase teams, pharmacologists refining fundamentals, scientists challenging legacy assumptions, and leaders who need decision-ready intelligence. The pace of GPCR innovation is accelerating—teams acting on today’s insights will set tomorrow’s standards while others play catch-up. Stay current. Stay confident. Stay ahead. 🟢 40 years of expertise at your fingertips: Explore the complete library ➤ ✳️ Want to know what’s inside? Read the latest articles ➤ Stay sharp between lectures. Subscribe to The Kenakin Brief today ➤

Watch Episode 173 A rejection letter ended his dream of becoming a physician-scientist. But for Ajay Yekkirala, that closed door lit the fuse for a career that would reimagine GPCR therapeutics — and lead to two biotech startups. What followed was a scientific journey that now spans two biotech startups, and a bold reimagining of GPCR-targeted therapeutics. In this episode, he shares his career story — one that begins with a failed goal, but ends up reshaping how we think about GPCR-targeted therapeutics. His work spans deep academic research, startup life, and the application of machine learning and pharmacology to GPCR drug discovery. More than a technical overview, this is a story of curiosity, persistence, and using science to meet unmet clinical needs, especially in the chronic pain and addiction space. The Role of Mentorship and Collaboration Initially set on a career in medicine, Ajay’s plan was to pursue an MD/PhD and become a physician-scientist. But when that route closed unexpectedly, he pivoted into a PhD program at the University of Minnesota. Throughout his career, Ajay benefited from mentors who not only guided his science, but challenged him to think strategically and translationally. For his postdoctoral training at Boston Children’s Hospital and Harvard Medical School, he joined the lab of Dr. Clifford Woolf, a leader in pain biology. There, Ajay expanded his understanding of neurobiology and translational research models, further refining his interest in bridging molecular insights with therapeutic design. This environment helped him see science as an ecosystem, where collaboration and interdisciplinary thinking were essential. He also began to think more deeply about the systemic barriers that slow down or prevent good science from reaching patients — particularly in underfunded fields like pain. Blue Therapeutics: Turning GPCR Biology Into a Business Ajay’s academic training planted the seeds for what would later become Blue Therapeutics, a startup he co-founded to develop non-addictive pain medications. The company’s scientific approach relied on targeting GPCRs — specifically opioid receptors — using biased agonists that could activate beneficial pathways while avoiding harmful ones. Starting Blue wasn’t glamorous. It was investor rejections, endless slide decks, and the steep learning curve of biotech business. But it was also a crucible: Ajay learned that science doesn’t matter if you can’t convince the world to believe in it. Launching Blue was Ajay’s first hands-on experience with biotech entrepreneurship. Moving from the lab to the business world required new skills: translating biological insight into investor-ready narratives, navigating startup fundraising, and building an operational team. The transition wasn’t without friction, but it gave him the ability to test science in a translational, real-world context — something he felt academia didn’t always support. The goal of Blue wasn’t just to publish or patent; it was to bring a novel, safer class of pain therapeutics to patients — an urgent need in the midst of the opioid crisis. Superluminal Medicines: AI/ML Meets GPCR Pharmacology As Ajay continued to explore how GPCR signaling could be leveraged for therapeutic innovation, he saw a gap in the drug discovery landscape. Despite decades of progress in structural biology and pharmacology, predicting how  a GPCR will respond to a given ligand — and what downstream effects it will trigger — remained incredibly complex. To address this, he co-founded Superluminal Medicines , a biotech company focused on integrating machine learning with structural and functional GPCR data. The company’s goal is to model receptor dynamics — including biased signaling — to predict drug behavior with greater accuracy and specificity. In July 2025, Superluminal Medicines announced advancing a selective, biased, MC4R agonist small molecule to IND-enabling studies for the treatment of Obesity. Where high-throughput screening saw chaos, Ajay saw patterns waiting to be decoded. Superluminal is building systems that learn from receptor movement, conformational shifts, and complex protein-protein interactions. By making receptor behavior computationally predictable, Ajay and his team are working to reduce the time and cost of developing new, more precise GPCR-targeted therapeutics. In August 2025, Superluminal Medicines announced a collaboration with Eli Lilly and Company to advance small molecule therapeutics for cardiometabolic diseases and obesity. Lessons From the Front Lines of Biotech Ajay’s experience in both early-stage biotech and academic science has given him a broad perspective on what it takes to innovate. He emphasizes that building a startup is not simply a continuation of research — it requires a mindset shift. The stakes are different. The pressures are different. But the core is still the same: solve a hard problem that matters. He also stresses that failure — whether scientific, personal, or organizational — is a feature, not a bug. From his early career redirection to startup setbacks, each step has added new layers to his thinking about drug development. Rather than being discouraged by challenges, he views them as forcing functions for creativity and growth. Advice for Young Scientists For early-career researchers, Ajay’s journey offers a powerful blueprint. He encourages scientists to think beyond the traditional academic path and to stay close to the problems they care most about solving. Whether it's chronic pain, addiction, or another unmet need, keeping the real-world impact in focus can clarify career decisions and research priorities. He also underscores the value of developing cross-functional skills — including communication, strategy, and leadership — especially for those considering biotech or entrepreneurial ventures. The ability to ask precise, translational questions is just as important as having technical expertise. Takeaway: Ajay Yekkirala’s story is not just about GPCR science or startup success. It’s about how moments of redirection — even disappointment — can open new paths to impact. By staying grounded in scientific rigor while embracing the tools of business and technology, he’s built a career that bridges the lab bench and the clinic. Ajay's career is proof that in science, the detours are often the real path forward

GPCR research requires turning data into insights for drug discovery Hi GPCR Friends, Every week, critical decisions in GPCR research hinge on subtle shifts in data. Trusting your eyes—or tradition—can cost time, money, and credibility. That’s precisely why Terry’s Corner delivers this week: practical, statistical tools that let you move from “I think” to “I know.” Breakthroughs this week:  Why Everyone’s Talking About Metabolic GPCRs; GPS for proteins: Tracking the motions of cell receptors; A Better Way to Treat Obesity; Unlocking the pharmacological potential of antibodies. 🔍 This Week in Dr. GPCR Premium: Sneak Peek Your weekly edge — curated signals you won’t find on public feeds. Industry insights:  Metabolic GPCRs climbing the spotlight; new tools tracking receptor motion; obesity drug strategies shifting; antibody pharmacology opening fresh doors. Upcoming events:  Major GPCR-focused symposiums and translational meetings are on the horizon — shaping agendas and collaborations across Europe and the U.S. Career opportunities:  Leadership-level roles in clinical operations and translational science, alongside multiple GPCR-focused postdoc positions. Must-read publications:  A structural modeling study revealing non-canonical mechanisms of chemokine-driven receptor activation. Terry's Corner – Curve Shifts Don’t Lie, But Your Eyes Might In early drug discovery, “those curves look different” is not enough. This week, Dr. Terry Kenakin walks you through which statistical tests actually answer the question you think you’re asking—so you can start making confident decisions. From t-test, ANOVA, F-test selection to power analysis  that prevents underpowered studies, this module hands you a practical framework to validate differences, confirm subtle shifts, and benchmark your results against literature or across assay types. Avoid wasted resources:  Stop relying on “n=3” by default. Power analysis tells you exactly how many replicates you need for 95% confidence. Eliminate subjective calls:  From t-tests to ANOVA and F-tests, know which tool to apply when, so debates about “what the graph says” end with evidence. Validate with confidence:  Benchmark your results against literature standards and confirm whether your assays hold up—or diverge in meaningful ways. Premium Members get a 50%+ discount when they join Terry’s Corner. 🚨 First-ever Live AMA with Dr. Kenakin  happens this month—exclusively inside Terry’s Corner. Bring the curve you’re debating. Ask. Challenge. Get an answer you can defend. Unlock Terry’s Corner ➤ Dr. GPCR Podcast – Ajay Yekkirala on GPCR Innovation In this episode, Dr. Ajay Yekkirala shares the journey from academic pharmacologist to biotech entrepreneur—bridging curiosity, AI/ML, and translational medicine. Learn entrepreneurial lessons rarely shared with postdocs. Understand how AI/ML and GPCR biology meet to unlock safer drugs. Gain career inspiration from Ajay’s bold questions and pivots. Listen to the whole conversation ➤ GPCR Happy Hour – Boston, September 2025 Space is limited. Big ideas aren’t. When the global biotech crowd lands in Boston for Discovery on Target. This is where the real conversations begin—made possible with the support of NIS, Proteos, and Axxam  . Expect a curated room of scientists, leaders, and investors ready to compare notes, spark collaborations, and accelerate programs. Forge high-value connections in an intimate setting. Be part of the nonprofit mission to unite the GPCR community. Don’t miss the conversations that will ripple long after the conference. Register now to secure your spot ➤ Why Dr. GPCR Premium Membership Gives You an Edge Premium delivers curated, noise-free intelligence every week: deep-dive expert lectures, classified industry news, priority event alerts, job opportunities, and insider commentary—designed to help you move faster, smarter. Where others sift through noise, Premium gives you distilled, relevant, and actionable insights. Whether you’re in discovery, translation, or strategic leadership, Premium ensures you never fall behind. FAQ: Premium Membership 🔹 What’s included? The complete Weekly News digest, curated jobs, upcoming events, classified GPCR publications, exclusive on-demand expert lectures, and member-only discounts. 🔹 Who is it for? GPCR scientists, translational pharmacologists, biotech discovery teams, and decision-makers who need career-relevant intelligence to stay ahead. 🔹 Why now? The pace of GPCR innovation is accelerating. Those who act on the right signals today will lead tomorrow’s breakthroughs—and avoid delays others won’t see coming. 👉 Don’t Fall Behind—Access the Edge You Need 👉 Already a Premium Member? Access this week’s full Premium Edition here ➤ What our members say 🗣️ "The content had enough depth to satisfy the hunger for theory while being full of practical knowledge." — DrGPCR University Attendee Stay informed. Stay connected. Stay ahead. 🚀 Join Premium Today ➤

Applications of Fluorescent Probes in Confocal Imaging of GPCRs: From Live to Fixed Cells GPCRs are present across cell membranes transmitting signals from the outside into the cells, making them an essential target in biomedical research . Studying their dynamics in both a spatial and temporal manner is key to understanding how they work in this signaling pathways, and one of the best tools to do so is fluorescence microscopy . To make the most out of this imaging technique, fluorescent probes must have high specificity, minimal phototoxicity and preferably be compatible with both live and fixes cell imaging. How Fluorescent Probes Enable High-Resolution Confocal Imaging of GPCRs To study the dynamics of GPCRs, the imaging method must be spatially precise and have real-time monitoring capabilities . This is why fluorescent tags, both attached to the protein or to pharmacophores, are so interesting. They retain the functional integrity of the GPCR while enabling selective excitation and collection of fluorescence from a specific focal plane, leading to better resolution and lower background noise. This technique can acquire three-dimensional image stacks, facilitating the reconstruction of GPCR distribution in tissue-like environment , in both a quantitative and qualitative manner. Figure 1. PerkinElmer High Content Analysis System Operetta CLS used by a Celtarys Research coworker. Analysis program Harmony 4.9 (PhenoLOGIC). A High Content Screening focused microscope that has a confocal-like mode as well. Optimizing Fluorescent Probe Selection for GPCR Imaging Probe selection is a key step to obtaining good and significative results. The biological context (live or fixed cells), the spatial temporal resolution and other experimental components should all be considered. For example, in live-cell imaging, probes should not be toxic and should be resistant to photobleaching. In the case of fluorescent ligands , where a fluorescent tag is attached to a pharmacophore , the receptor also keeps its original structure without any modification, also maintaining its physiological activity. Ligand-directed labelling strategies  are a newly developed way to attach a fluorescent tag to a GPCR in a covalent manner. This preserves functionality while being compatible with washing procedures. Another strategy is the use of self-labelling tags  such as SNAP-tag and HaloTag. In this strategy the GPCR is modified genetically to fuse an engineered enzyme. This enzyme has been modified so a small molecule will covalently bind to it, which can in turn be attached to a fluorescent tag. This provides flexibility in labelling the GPCRs but may interfere with functional activity of the receptors. SNAP-tag has been successfully used while preserving activity. They can be combined with other ligands and are very interesting in TR-FRET (Time-Resolved Förster Energy Resonance Transfer) assays. Exploring the Applications of Confocal Fluorescence Microscopy in GPCR Research In GPCR research one of the best used of confocal microscopy is the study of receptor trafficking, localization and signaling dynamics . This method is very precise at determining these parameters thanks to capturing fluorescence from a single focal plane. It can even study the GPCR distribution within endocytic vesicles and across subcellular compartments. If the experiment is done on live cells , tracking real-time receptor internalization becomes possible. Studying ligand-induced clustering and evaluating protein-protein interactions becomes possible if using FRET . On the other hand, in fixed cells studies, it facilitates the structural context necessary to map receptor localization in defined states (pharmacological stimulation, genetic modification, disease models…). Figure 2.Left panel, confocal microscopy of living cells incubated for 1h at 37ºC with CELT-327. Right panel, the fluorescent signal is displaced when, after incubating with CELT-327, cells are incubated with an excess of the A2B/A3 antagonist, MRS1220. Fluorescence Microscopy validation performed in the ONCOMET laboratory (Health Research Institute of Santiago de Compostela). At Celtarys, our GPCR fluorescent ligands are designed with a variety of photophysical properties to meet your needs for confocal imaging. Come check out our products or contact us for more information! References Fessl T, Majellaro M, Bondar A. Microscopy and spectroscopy approaches to study GPCR structure and function. Br J Pharmacol. 2023 Dec 12. doi: 10.1111/bph.16297.  Jang W, Senarath K, Feinberg G, Lu S, Lambert NA. Visualization of endogenous G proteins on endosomes and other organelles. eLife. 2024 Nov 8; 13:RP97033. doi: 10.7554/eLife.97033.3   Maurel D, Comps-Agrar L, Brock C, Rives ML, Bourrier E, Ayoub MA, Bazin H, Tinel N, Durroux T, Prézeau L, Trinquet E, Pin JP. Cell-surface protein-protein interaction analysis with time-resolved FRET and snap-tag technologies: application to GPCR oligomerization. Nat Methods. 2008 Jun;5(6):561-7. doi: 10.1038/nmeth.1213.  Navarro G, Sotelo E, Raïch I, Loza MI, Brea J, Majellaro M. A Robust and Efficient FRET-Based Assay for Cannabinoid Receptor Ligands Discovery. Molecules. 2023 Dec 15;28(24):8107. doi: 10.3390/molecules28248107.

Space is limited. Big ideas aren’t. When the biotech world gathers in Boston, this is where the real conversations begin. GPCR Happy Hour: Where meaningful connections flourish beyond the conference hustle, in collaboration with NIS, Proteos, and Axxam. Why GPCR Happy Hour? The conference floor is crowded. The panels are packed. Everyone’s rushing from one talk to the next. But the truth? The most valuable conversations don’t happen under fluorescent lights — they happen when the ties are loosened, the glasses are full, and the pressure is off. That’s exactly why we created GPCR Happy Hour . Every September, Boston welcomes the global biotech and drug discovery community. Scientists, investors, and CRO professionals fly in from around the world, while Boston’s own vibrant life sciences hub shows up in full force. GPCR Happy Hour is where these two worlds meet. It’s not just networking. It’s where partnerships spark, ideas collide, and the GPCR community grows stronger — together. Why It Matters Connect with peers across biotech, CROs, and investment who are driving discovery forward Meet both the global biotech community and Boston’s local innovators in one room Be part of Dr. GPCR’s nonprofit mission to unite and empower the GPCR community worldwide FOMO is real: if you’re not in the room, you’ll be hearing about the connections you could have made. Be Part of the GPCR Community Dr. GPCR is a nonprofit global community  dedicated to building a strong, connected GPCR ecosystem. Our mission is simple: bridge science and industry  by connecting researchers, biotech, CROs, and pharma leaders around GPCR drug discovery. GPCR Happy Hour is more than a social event. It’s a chance to stand shoulder-to-shoulder with peers from across the globe and the Boston biotech scene, to share ideas, spark collaborations, and strengthen the ties that keep this community thriving. Our Sponsors This event would not be possible without the generous support of our sponsors: NIS Proteos Since 2007, NIS   has been a trailblazing CRO making cryo-electron microscopy (cryo-EM) accessible to pharma and biotech companies of all sizes. With the largest fleet of transmission electron microscopes in North America, NIS delivers cutting-edge imaging and analysis that accelerates the discovery of new and life-changing therapeutics. Their areas of focus include structural biology, protein production from Proteos, and nanoparticle characterization. Their expertise, collaboration, and commitment to quality make them an indispensable partner in modern drug discovery. Axxam Axxam is a leading provider of integrated discovery services, supporting the entire drug discovery process from target identification to lead optimization. The company has long-standing expertise in G protein–coupled receptor (GPCR) biology—one of the most important and validated target classes in drug discovery. Axxam’s capabilities span the full spectrum of GPCR families, including aminergic, peptide, lipid, and chemosensory receptors (such as bitter and metabolic receptors). Leveraging decades of experience, their services include AI-driven target identification, target validation, assay development, compound management, and high-throughput screening in both 384- and 1536-well formats. Screening campaigns can be performed using Axxam’s high-quality compound collections—both synthetic and natural—or client-provided libraries, followed by hit validation and hit-to-lead progression. Axxam also integrates breakthrough tools throughout the discovery process, including its pioneering organellar electrophysiology platform, iPSC-derived models, optogenetics, and high-content screening techniques such as cell painting assays. This comprehensive approach enables Axxam to support clients worldwide in identifying and optimizing new therapeutic opportunities across a wide range of disease areas. Event Details 📍 Location:  Pressed Cafe on Huntington Ave in Boston 📅 Date:  September 24, 2025 ⏰ Time:  6-8 pm EST 👥 Capacity:  Space is limited — early registration is recommended Secure Your Spot This isn’t another crowded mixer. It’s a curated room of GPCR biotech leaders, scientists, and investor professionals  — and space is limited. Register Now 👉 Bring a colleague you trust . 👉 Don’t miss the chance to be part of the conversations that will ripple far beyond Boston. ✨ GPCR Happy Hour: Where science, business, and opportunity meet after hours.

If you’ve ever squinted at two curves and thought, “That looks different… I think” , you already know the trap. In drug discovery, intuition creeps in. Eyes deceive. And when decisions ride on subtle shifts, “looks different” isn’t good enough. You don’t need sharper eyesight. You need statistical methods that tell you, with confidence, whether the effect you’re seeing is real or just noise. This session gives you exactly that. By the end, you’ll know how to choose the right test, design experiments with power built in, and validate results against the standards that matter. No more guesswork, only decisions you can trust. In This Session, You’ll Gain: ✅ The ability to calculate how many replicates you really  need for 95% confidence ✅ Tools to choose the right statistical test for means, curves, or linear responses ✅ A framework for validating whether your results match literature standards—or diverge in meaningful ways From Guesswork to Numbers You’ve run your experiment. Two data sets sit in front of you. They look  different. But are they? The first trap in drug discovery is relying on visual inspection. Scatter can masquerade as signal. Subtle shifts vanish in noise. What you need is a number that tells you whether those differences are real. That’s where t-tests  come in. By comparing two means (paired or unpaired) you’ll learn whether the divergence is genuine or whether random variation explains it. No more arguments about “what the graph seems to say.” You’ll move from “I think”  to “I know.” And once you understand the logic, you’ll see how it scales. Two groups? t-test. Three or more groups, or multiple variables creeping in? That’s where ANOVA  steps up. Same principle, broader reach. How Many Replicates Do You Really Need? The second trap is habit. Most labs default to “n=3” or “n=6.” But those numbers don’t come from rigor; they come from tradition. With power analysis , you’ll stop guessing. Instead, you’ll calculate exactly how many replicates are needed to detect the differences that matter, at the confidence level you demand. For high-throughput screens where sensitivity isn’t critical, you’ll save time by running fewer replicates. For critical experiments where tiny differences mean millions of dollars, you’ll ensure enough replicates to trust your decision. Once you learn to design with power analysis, you’ll never run blind again. When Curves Shift Some of the most difficult calls in pharmacology happen when two curves look  slightly shifted. Is it a real pharmacological effect, or just noise? Here’s where the F-test  becomes indispensable. Instead of relying on debate—or worse, intuition—you can calculate an F-value that objectively shows whether the two curves belong to one population or two. Real curve shifts? Captured. Artifacts? Dismissed. This ability transforms meetings from endless discussions to clear decisions. Straight Lines, Slopes, and Systems Not all data bends into curves. Sometimes you’re working with linear fits: Schild plots, dose ratios, regression models. Here, the question is whether two lines describe the same system, or whether treatment has shifted slope or intercept. Enter ANOVA (Analysis of Variance).  It gives you the power to compare slopes and elevations statistically—so you can confirm whether your system is consistent or diverging in meaningful ways. What used to be a gray area— “maybe these lines are different?” —becomes a black-and-white decision. Does Your Assay Agree With the Literature? Your experiment gives a pKB of 8.0. The literature says 7.5. Is that consistent, or is your assay biased? With confidence intervals and modified t-tests , you’ll be able to: Confirm whether your mean truly overlaps with accepted values Verify if binding and functional assays deliver consistent results Decide with confidence whether a new method is interchangeable with existing ones Instead of vague comparisons, you’ll have statistical clarity on whether your assay is valid or drifting. What You’ll Walk Away With By the end of this session, you won’t just “know about statistics”, you’ll know how to use  them to sharpen every discovery decision. Specifically, you’ll be able to: Design experiments with the right replicate count to balance rigor and efficiency Choose the correct statistical test for your data structure Compare curves and lines without guesswork Validate your results against standards and across methods Trust that your conclusions reflect reality, not bias This is more than learning tools. It’s learning how to design, analyze, and decide with confidence built in. Statistical Methods in Drug Discovery: Your Edge If you’re still making calls by sight, habit, or tradition, you’re leaving risk on the table. With the right methods, you’ll know (not hope) that your results are real, reproducible, and actionable. This isn’t just another lecture. It’s a shift in how you approach discovery. And once you make that shift, you’ll never go back. Unlock “Statistical Analysis” now Only in Terry’s Corner Why Terry’s Corner Your work demands clarity, speed, and confidence, especially when early decisions determine which programs move forward. Terry’s Corner is designed to give you the edge. Here, you’ll find: Weekly lectures  that sharpen the tools you actually use in discovery A growing on-demand library  of lessons you can revisit whenever you need them Exclusive access to the next AMA session Direct engagement opportunities  through AMAs and topic suggestions Practical insights  distilled from decades of pharmacology experience Whether you’re validating assays, refining models, or deciding which leads to advance, Terry’s Corner ensures you’re working with proven strategies, not assumptions. Stay current. Stay confident. Stay ahead. 🟢 40 years of expertise at your fingertips: Explore the complete library ➤ ✳️ Want to know what’s inside? Read the latest articles ➤ Stay sharp between lectures. Subscribe to The Kenakin Brief today ➤ #ttest #ANOVA #poweranalysis #curvecomparison #ftest #assayvalidation #experimentaldesignstatistics #assayreproducibility #ANCOVA #pharmacology #drugdiscovery

Watch Episode 172 What happens when the career you planned no longer feels right? For Catherine Demery, it meant rewriting everything on her own terms. She entered undergrad set on becoming a pharmacist. After excelling in the PCAT and gaining admission to pharmacy school at the University of Michigan, it seemed like her path was locked in. But something shifted. “I kind of had an identity crisis because I think I realized in that moment that I didn't want to be a pharmacist but I had tailored four years of my life to doing so." Two weeks before orientation, Catherine deferred her acceptance. It was a bold, uncertain move—but one that became the catalyst for a new trajectory. She found herself drawn toward the science behind the drugs, rather than their clinical application. That insight eventually led her into industry. Learning the Lab, Learning Herself During her time at the contract research organization (CRO) in Ann Arbor, Catherine was immersed in analytical work under stringent GLP/GMP standards. It was here that the disciplined structure of industry science helped her re-find purpose and build confidence for what came next. “This wasn’t with much foresight for a couple years down the road. It was mostly just because, I need to be back in the lab.” In that environment, every project brought new challenges—deadlines, documentation, and deliverables for paying clients. Catherine’s methodical retention of those skills later gave her a solid foundation in her academic work, even when expectations were looser in academia. The Spark of Addiction Science After two years in industry, Catherine enrolled in a master’s program in pharmacogenomics at Manchester University. There, she chose to write a review on genetic variation in susceptibility to alcoholism and opioid addiction—a decision that would reshape her academic ambitions. “...I had a light bulb moment where I felt for the first time in my life, I understood why people pursued a PhD. I was staying up super late. I was excited to work on this, till 2 or 3 a.m.” That project was her lightbulb moment. She finally understood what it meant to be driven by a research question, not just assigned to one. For the first time, she saw herself as a future researcher, not just a technician or a student. A Detour Through Immunology Her growing interest in addiction led her to the NIH’s Perinatology Research Branch in Detroit. While her work there focused on immunological changes in pregnancy—not addiction—it was a valuable chapter. She gained exposure to in vivo models, immunology, and complex study design, while also getting closer to patient-centered research. “It really forced me to kind of patch up all my immunology holes and then apply them. I came away from that job with just a whole new appreciation for immunology and for pregnancy. It was really, really fascinating… and just eye opening to a part of the world that I don’t think I would have put that much thought into ever again.” This experience sharpened her conceptual range and prepared her for the next step. Returning to the Opioid Questions That Mattered Now, as a PhD candidate in the Traynor and Anand labs at the University of Michigan, Catherine is focused on the mechanisms of opioid-induced respiratory depression, particularly involving fentanyl and xylazine. Her current work examines how these substances, when used alone or together, impair breathing in mice. She uses whole-body plethysmography and pulse oximetry to dissect the specific ways these drugs impact the respiratory cycle. It’s rigorous pharmacology, but deeply tied to urgent public health needs. And it’s also deeply personal. "I've always been really passionate and somewhat sensitive to people who struggle with opioid abuse. I had a few friends who became addicted and, really sadly, many of whom actually passed away as a result of an overdose. And so, that certainly shaped my interests and passions as a scientist." What Can You Learn from Catherine’s Story? A career pivot is not a failure—it’s a refined strategy. Industry can build skills that academia often overlooks. Your passion might not come first—it might come from doing the work. The most impactful science is often personal. Technical discipline is transferable—even across research cultures. The Importance of Passion in Research Catherine's journey highlights the importance of passion in research. It is not just about following a predetermined path; it is about discovering what truly drives you. Passion can lead to groundbreaking discoveries and a fulfilling career. When you find something that excites you, it can transform your work into a source of joy and motivation. Catherine's experience serves as a reminder that it is never too late to change direction and pursue what you love. Embracing Change and Uncertainty Change can be daunting, especially when it involves stepping away from a well-defined career path. However, embracing uncertainty can lead to unexpected opportunities. Catherine's decision to defer pharmacy school was a leap of faith that opened new doors. In life and career, taking risks can lead to personal and professional growth. It is essential to remain open to new experiences and to trust your instincts. This mindset can lead to a more fulfilling and successful career. Conclusion: A Journey of Self-Discovery Catherine Demery's story is one of self-discovery and resilience. It shows that career paths can evolve, and that it is possible to find fulfillment in unexpected places. Her journey illustrates the power of following one's passion and the importance of being adaptable in the face of change. In the end, it is about finding what resonates with you and pursuing it wholeheartedly. Catherine's experience serves as an inspiration for anyone considering a career change or seeking to align their work with their passions. _______ Keyword Cloud : #XylazineResearch #OpioidPharmacology #muOpioidReceptor #RespiratoryDepression #AddictionScience #DrGPCRecosystem #FentanylOverdose

Watch Episode 172 The Bigger Lesson Purpose-driven science works because it creates resilience. Careers built on prestige, titles, or external pressure can burn out quickly. But careers built on urgency, alignment, and meaning are the ones that last. That’s what makes Catherine Demery’s path stand out. Her choice to stay in academia isn’t about rejecting industry—it’s about embracing the freedom to chase the questions that keep her up at night. Questions about how opioids impair breathing, why xylazine complicates interventions, and how receptor-level insights can save lives. Her journey shows that scientific careers aren’t defined by early certainty. They’re defined by the moments when passion and purpose align—and by the courage to follow them. Why Purpose Matters in Science For some researchers, science is a job. For others, it’s a calling. For Catherine, it became both—after years of uncertainty, pivots, and practical lab experience that grounded her passion in real-world urgency. Her story is about more than experiments or data points. It’s about finding purpose through loss, choosing academia when many peers walk away, and designing science that stays connected to public health. In this episode, Catherine reflects on how her identity as a scientist took shape, why she’s committed to academic research, and how her work on opioids and respiratory depression continues to evolve. The Moment Science Became Purpose Catherine didn’t begin her career with a clear plan to pursue a PhD. Like many young scientists, she explored different paths and gained industry experience before realizing she belonged in research. The turning point came during her master’s program in pharmacogenomics. While writing a literature review on opioid and alcohol addiction susceptibility, something shifted. The work no longer felt like an assignment—it felt like a calling. “That was kind of a signal to me that maybe I should start thinking about a PhD,” Catherine recalls. It was the first time late nights in the lab weren’t a burden but a sign of genuine engagement. That alignment between curiosity and urgency set her on the path toward doctoral research. Why Catherine Chose Academia At a time when many early-career scientists debate whether to stay in academia or move into industry, Catherine speaks with unusual clarity about her choice. “I really like academia. I really want the freedom to keep studying what interests me specifically, and I’ve just really enjoyed the flexibility and the focus on learning,” she explains. For her, academia isn’t about prestige or climbing the career ladder. It’s about having the freedom to pursue questions that matter—questions tied to urgent public health crises like the opioid epidemic. Industry gave her useful skills, but academia gave her purpose. How Her Experiments Mirror Real Life What makes Catherine’s work distinctive is how closely it reflects the conditions people face outside the lab. Rather than treating opioid pharmacology as a purely theoretical exercise, she collaborates with harm-reduction groups such as the Red Project in Grand Rapids  to ground her models in reality. “They’ve seen a 30 to 60 percent increase in the number of fentanyl samples that contain xylazine in the past year.” That kind of street-level data shapes everything: dosing strategies that reflect actual potencies in seized samples, drug combinations that mirror contamination patterns, and experimental designs that evolve with new adulterants. This approach makes her models not just rigorous, but translational—bridging the gap between receptor pharmacology and public health. What’s Next in Her Opioid Research Catherine’s current experiments focus on outcomes such as respiratory rate, tidal volume, and oxygen saturation in mice exposed to fentanyl and xylazine. But she’s preparing to probe deeper into mechanisms. Her next steps include using floxed mouse models  and viral tools  to dissect the downstream pathways in opioid-induced respiratory depression. She is especially interested in mu-opioid receptor signaling  and how xylazine, as an alpha-2 adrenergic agonist , complicates the picture. For Catherine, this isn’t just scientific curiosity—it’s urgency. That personal loss transforms complex receptor pharmacology into something immediate and human. Lessons from Catherine’s Story Catherine’s career challenges the idea that success requires a straight line. She didn’t have a roadmap at 22. Instead, she followed the signals that kept her engaged and energized. Industry experience gave her perspective, but purpose came from aligning research with urgent, real-world problems. For her, the opioid crisis isn’t an abstract dataset—it’s a lived experience that informs her drive as a scientist. Her story is a reminder that clarity often emerges through action, not planning. Real-world data should guide how we build preclinical models. Academic success is less about prestige than about impact. And GPCR pharmacology isn’t just an academic pursuit—it’s essential to understanding and responding to today’s evolving overdose crisis. Closing Reflection “I’ve lost friends to overdose. That’s part of what motivates me. It makes the work feel urgent.” That urgency, more than titles, positions, or prestige, is what sustains a lasting career in science. Catherine’s story shows that when purpose drives research, science becomes more than a job—it becomes a calling.

In the realm of molecular research, precise interpretation is crucial; a misread curve can lead to lost compounds. Hello GPCR Enthusiasts, Interpreting binding data isn’t optional—it’s career-defining. When assays behave unpredictably, the wrong interpretation doesn’t just waste time; it costs viable compounds, credibility, and millions in development risk. Breakthroughs this week: Decoding ADGRE5 signaling; Eli Lilly’s obesity pill vs Novo’s Wegovy; Certa Therapeutics patents GPR68 antagonists. 🔍 This Week in Dr. GPCR Premium: Sneak Peek Every week, Premium Members get curated intelligence they won’t find in open channels. Here’s a preview of what’s inside this week’s Premium Edition: Industry insights:  Metabolic GPCRs in the spotlight; receptor motion tracking tools; obesity treatment race between Eli Lilly and Novo Upcoming events:  September GPCR symposia across Europe, UK, and online—including neuroGPCR signaling deep-dives. Career opportunities:  Postdocs in GPCR biophysics and assay development; industry scientist roles at BPS Bioscience. Must-read publications:  Tryptophan-cholic acid and MRGPRE in glucose homeostasis; Biased signaling in short- vs long-acting β2-agonists. Terry's Corner - The Truth About Allosteric Displacement Allosteric binding isn’t just a twist in the pharmacology playbook—it rewrites the rules entirely. This week, Dr. Terry Kenakin exposes why traditional displacement logic breaks down in allosteric systems, and how overlooking this can derail entire programs. Protect your pipeline:  Misinterpreting displacement curves in allosteric assays means discarding viable compounds—or worse, advancing misleading ones. Gain competitive clarity:  Learn how binding and function diverge, and why that divergence is the key to harnessing allostery, not fearing it. Avoid costly blind spots:  Discover how G protein stoichiometry can dictate whether your assay informs—or deceives. 💡 Premium Members also receive a 50%+ discount  when they join Terry’s Corner. Sharpen your discovery decisions ➤ Yamina’s Corner - The Hidden Cost of Busy A GPCR program can collapse—not because of bad science, but because brilliant teams are forced into duct tape systems. Yamina’s Corner reveals how fragmented data, undefined workflows, and ambiguous decision gates silently bleed six figures from every DMTA cycle. Eliminate chaos tax:  Every two-week delay in DMTA cycles costs hundreds of thousands—avoidable with precision systems. Stop wasting talent:  When senior leaders spend nights copy-pasting data, your burn rate accelerates while innovation stalls. Blueprint for survival:  Continuous improvement and operational scaffolding—not more hires—are the real drivers of resilience. Read the article now ➤ Discovery on Target - The Next Wave of GPCR Drug Discovery The 20th Annual GPCR-Based Drug Discovery Conference  isn’t just another event—it’s where the frameworks shaping the next decade are revealed. From biased ligands to computational targeting, this is where the pipelines of the 2030s begin. Featured Talk: Dr. Terry Kenakin on The Kinetics of Allostery . Exclusive Discount: Use code DRGPCR25  for $200 off. Secure your seat today ➤ Why Dr. GPCR Premium Membership Gives You an Edge The GPCR field is advancing at breakneck speed. Premium delivers clarity where noise dominates.  Each week, you gain curated intelligence across science, careers, and strategy: Deep-dive expert lectures and frameworks. Classified industry updates and event alerts. Tailored job opportunities and career matchmaking. Exclusive discounts and member-only access to resources. With Premium, you move faster, smarter, and more confidently than peers relying on scattered signals. FAQ: Premium Membership 🔹 What’s included? The complete Weekly News digest, curated jobs, upcoming events, classified GPCR publications, exclusive on-demand expert lectures, and member-only discounts. 🔹 Who is it for? GPCR scientists, translational pharmacologists, biotech discovery teams, and decision-makers who need career-relevant intelligence to stay ahead. 🔹 Why now? The pace of GPCR innovation is accelerating. Those who act on the right signals today will lead tomorrow’s breakthroughs—and avoid delays others won’t see coming. 👉 Don’t Fall Behind—Access the Edge You Need 👉 Already a Premium Member? Read the Premium edition here ➤ What our members say 🗣️ "Dr. Kenakin is a leading expert in the field. Aside from his vast experience in drug development, not to mention his extensive publication record, Dr. Kenakin is a masterful teacher and communicator." — DrGPCR University Attendee The difference between stalled programs and breakthrough therapies often lies in a single insight delivered at the right time. Premium Membership ensures you never miss it. 🚀 Join PremiumToday ➤

Exploring the kinetic factors that enhance in vivo efficacy beyond traditional potency metrics, as presented by Dr. GPCR. Hey GPCR Fans, This week's breakthroughs are crucial for staying ahead in the rapidly evolving landscape of GPCR research and drug discovery. Dr. Terry Kenakin's insights on target residence time can reshape how you evaluate and advance lead compounds, potentially saving your team from costly late-stage failures. That's exactly what Dr. GPCR delivers every week: practical tools and critical intelligence to elevate your science and sharpen your decisions. Breakthroughs this week: Novo Nordisk cuts Ozempic® cost; Nxera launches obesity pipeline; Superluminal–Lilly cardiometabolic partnership; New GPCR allosteric sites; GPCR signaling potentiation by ATP and sugars. 🔍 This Week in Dr. GPCR Premium: Sneak Peek Get a glimpse of the in-depth intelligence available exclusively to our Premium Members this week: Industry insights:  Discover the latest strategic moves in the pharmaceutical sector, from new pipelines targeting obesity to significant collaborations in cardiometabolic disease, and gain insights into novel approaches in neurodegeneration and antibody therapeutics. Upcoming events:  Stay informed about key global conferences and symposia focusing on GPCRs, neuropharmacology, drug discovery, and biophysics, ensuring you don't miss crucial networking and learning opportunities. Career opportunities:  Explore a selection of high-level job openings in high-throughput screening, research, biologics development, clinical operations, and biostatistics within leading organizations. Must-read publications:  Stay updated on cutting-edge research, including the potentiation of GPCR signaling by ATP and sugar monophosphates and the identification of a novel allosteric site on the vasopressin V2 receptor. Terry's Corner - Unlock the Power of Target Residence Time in Your GPCR Drug Discovery Pipeline Gain a critical edge by understanding the in vivo efficacy drivers overlooked by traditional potency metrics. Are your promising in vitro results failing to translate into real-world clinical success? Dr. Terry Kenakin’s latest insights delve into target residence time, revealing why kinetic persistence often trumps binding affinity for in vivo efficacy. Discover how factors like restricted tissue diffusion and receptor density can dramatically alter drug action, potentially unlocking the true potential of your lead compounds. Problem Solved:  Eliminate the blind spots in your drug evaluation process, moving beyond simple potency measures to understand the dynamic interactions that govern in vivo effectiveness. Competitive Edge:  Identify high-value compounds that might be missed by traditional screening methods, gaining a first-mover advantage in developing more effective therapeutics. Threat Avoided:  Prevent costly late-stage failures by incorporating kinetic modeling early in your pipeline, ensuring your candidates have the persistence needed for clinical impact. ➡️  Premium Members get 50%+ discount when they join Terry’s Corner. Access this week’s key insight ➤ Dr GPCR Podcast – Decoding the Deadly Duo: Xylazine, Fentanyl, and Respiratory Depression Understand the synergistic mechanisms driving the escalating opioid crisis and the crucial role of GPCR pharmacology. The opioid crisis is evolving with the dangerous combination of fentanyl and the veterinary sedative xylazine. This week’s featured podcast episode with Catherine Demery explores the distinct yet lethal mechanisms by which these drugs impair respiration. Learn how fentanyl slows inhalation via opioid receptors, while xylazine prolongs exhalation through alpha-2 adrenergic receptors, creating a synergistic effect that drives overdose deaths. Catherine’s research, blending GPCR signaling studies with public health data, offers critical insights into this urgent crisis. Problem Solved:  Gain a deeper understanding of the pharmacological underpinnings of opioid overdose, informing the development of more effective intervention strategies. Competitive Edge:  Stay informed on emerging public health threats and the scientific research aimed at addressing them, positioning your work at the forefront of critical biomedical challenges. Threat Avoided:  Recognize the growing prevalence and dangers of xylazine-laced opioids, enabling you to contribute to solutions and understand the broader impact on public health. Listen now to understand how two mechanisms intersect—and why pharmacologists are critical in addressing this crisis ➤ Call for Papers – GPCRs: Signal Transduction Volume II With over 21,000 views  and 7,785 downloads  from Volume I, the Signal Transduction  Research Topic is back. Volume II invites experts to deepen our collective understanding of GPCR pathways in health and disease. Manuscript summary deadline: 24 September 2025 . Final submissions: 12 January 2026 . Why contribute: Join a global, like-minded GPCR community. Shape the next generation of cellular biochemistry research. Amplify your work with high-impact visibility. Submit your paper today to secure your work in Volume II ➤ Why Dr. GPCR Premium Membership Gives You an Edge Every week, Premium delivers noise-free intelligence : expert-led courses, classified industry insights, curated events, exclusive job opportunities, and insider commentary. Designed for GPCR scientists and translational teams, Premium keeps you informed on the science, careers, and business moves shaping drug discovery. Unlike fragmented feeds and endless searches, Premium is structured to help you move faster, smarter, and with greater clarity. FAQ: Premium Membership 🔹 What’s included? The complete Weekly News digest, curated jobs, upcoming events, classified GPCR publications, exclusive on-demand expert lectures, and member-only discounts. 🔹 Who is it for? GPCR scientists, translational pharmacologists, biotech discovery teams, and decision-makers who need career-relevant intelligence to stay ahead. 🔹 Why now? The pace of GPCR innovation is accelerating. Those who act on the right signals today will lead tomorrow’s breakthroughs—and avoid delays others won’t see coming. 👉 Don’t Fall Behind—Access the Edge You Need 👉 Already a Premium Member? Access this week’s full Premium Edition here ➤ What our members say 🗣️ “The best pharmacology teacher teaming up with the best GPCR community platform to help train and inspire the next generation of scientists.” — Dr. GPCR University Course Attendee Ready to gain a competitive advantage? 🚀 Upgrade to Premium Membership Today!  🚀 👉 Become a Premium Member Today ➤

The ability to identify compounds that interact with molecular targets involved in disease pathways is where the development of new therapeutics lies. Target-based screening is now a fundamental pillar of drug development, and GPCRs are key targets for disease treatment. Using this method, binding affinity, kinetics and selectivity can all be measured and used to establish the best compounds. To efficiently run these screening campaigns high throughput screening assays are used. They provide rapid and scalable assessment of pharmacological parameters. There are several fluorescent techniques used in HTS, among them Fluorescence Polarization (FP) is especially useful since it allows real time detection and there is no need for washing steps. How Fluorescence Polarization Assays Work: Principles and Applications in GPCR Research FP assays work on the principle that a fluorescent ligand bound to protein rotates slower than a free fluorescent ligand. This combined with the use of polarized light leads to a signal that can only be detected when the fluorescent ligand is bound to the protein. When polarized light hits a free fluorescent ligand, its rotation speed is so fast that the emission is depolarized, which is not read by the FP filters. On the other hand, when the polarized light hits the bound fluorescent ligand, the slower rotation speed means a polarized emission which is detected by the filter. This means no washing steps are needed to reduce background signal. Figure 1. Mechanism of fluorescence polarization. Adapted from: Zhang Y, Tang H, Chen W, Zhang J. Nanomaterials Used in Fluorescence Polarization Based Biosensors. Int J Mol Sci. 2022 Aug 3;23(15):8625 . This technique is most effective at studying interactions between large proteins and small ligands thanks to this change in rotation speed. This makes them very useful for GPCR drug discovery, since receptors are a lot bigger than their small molecule ligands. Optimizing GPCR Drug Discovery with Fluorescence Polarization: Key Advantages and Future Perspectives 1.       FP assays are convenient and easy to manipulate. They are more accessible than radioligand assays, since they do not require complex equipment for analysis and plate readers are usually available in regular laboratories, although not all have FP filters, they are usually included. In this article by Miranda-Pastoriza et al. we have demonstrated that both radioligands and FP assays using CELT-228 A3AR fluorescent antagonist provide similar binding affinity values. These results support the use of fluorescence-based screening methods as a reliable alternative to classical radioligand binding assays. Table 1. Comparison of hA3 binding affinities or percentage of displacement at 1 µM measured for different compounds in human cell lines. hA₁, hA₂A, hA₂B, and hA₃ (radioligand assays):  Displacement of specific radiolabeled ligands in CHO, HeLa, or HEK-293 cells, expressed as K i (nM ± SEM, n=3) or percentage displacement at 1 µM (n=2). hA₃ (fluorescence polarization assay):  Displacement of CELT-228 detected by FP measurements (n=3). Reference compounds XAC, ISVY-130, and MRS 1220 were included as standard A₃AR antagonists.  2.       Compatible with various sources of GPCRs. Conventional membrane preparations or baculoviruses can be used among others. We highlight this article by Tahk et al.  where they used CELT-419 for D3 dopamine receptor binding assays in baculoviruses. 3.       Not time-sensitive Once equilibrium has been reached the assay remains stable for extended periods (at least 60 to 90minutes), being limited by the stability of the fluorescent ligand or receptor preparations in the assay media. 4.       No energy transfer between two fluorophores. Unlike other techniques (FRET-based), only one fluorophore is needed. In this case only the distance between fluorophore and protein matters (for the rotation to be slowed), not the distance between the protein, donor and acceptor. Advancing Fluorescence Polarization Assays with Custom Fluorescent Ligands Looking ahead, fluorescence polarization technology is expected to expand its role in GPCR research through the development of novel fluorescent probes and advanced imaging techniques. New generations of fluorophores with improved photostability and brightness will enhance assay sensitivity, while integration with artificial intelligence-driven data analysis will accelerate hit identification and lead optimization. The future of fluorescence polarization assays is closely tied to fluorescent ligands. Contact us  to drive further advancements in GPCR drug discovery!   References Kumar V, Chunchagatta Lakshman PK, Prasad TK, Manjunath K, Bairy S, Vasu AS, Ganavi B, Jasti S, Kamariah N. Target-based drug discovery: Applications of fluorescence techniques in high throughput and fragment-based screening. Heliyon. 2023 Dec 19;10(1):e23864. doi: 10.1016/j.heliyon.2023.e23864.  Miranda-Pastoriza D, Bernárdez R, Azuaje J, Prieto-Díaz R, Majellaro M, Tamhankar AV, Koenekoop L, González A, Gioé-Gallo C, Mallo-Abreu A, Brea J, Loza MI, García-Rey A, García-Mera X, Gutiérrez-de-Terán H, Sotelo E. Exploring Non-orthosteric Interactions with a Series of Potent and Selective A3 Antagonists. ACS Med Chem Lett. 2022 Jan 10;13(2):243-249. doi: 10.1021/acsmedchemlett.1c00598.

Watch Episode 172 The Bigger Picture: GPCR Science Meets Public Health At its core, Catherine Demery’s research  is about receptors and signaling pathways—how mu-opioid  and alpha-2 adrenergic receptors  interact to disrupt breathing. But it’s also about public health urgency. Her findings highlight how fentanyl suppresses inhalation while xylazine prolongs exhalation, creating a respiratory cycle that collapses from both ends. The combination is not merely additive; it’s synergistic, shrinking tidal volume even when breathing rate appears stable. The real killer, however, is apnea—those silent pauses where oxygen saturation crashes, often missed by surface-level monitoring. And because naloxone cannot reverse xylazine, the interventions that once worked for opioid overdoses are no longer enough. With street-level contamination rising faster than medicine can adapt, Catherine’s work shows why overdose research must evolve alongside the drug supply. For scientists, this means rethinking how we study GPCR-mediated respiratory depression. For clinicians, it’s a warning to update how we detect and respond to overdose. And for policymakers, it’s a stark reminder: the U.S. no longer faces a “fentanyl crisis”—it faces a polysubstance crisis. A Crisis That’s Redefining Overdose In 2023, more than 107,000 Americans died from drug overdoses , the highest number on record. Fentanyl was implicated in the vast majority of those deaths. Yet fentanyl is increasingly not alone. Xylazine , a veterinary sedative never intended for human use, is infiltrating the opioid supply in cities and rural areas alike. In states such as Michigan and Pennsylvania, it has been detected in more than one in four fentanyl-related deaths . This new pairing is uniquely dangerous. Fentanyl acts with devastating potency at the mu-opioid receptor , while xylazine exerts sedative effects through a different system altogether. And because naloxone only targets opioids, it cannot reverse xylazine. That gap leaves clinicians, first responders, and families without a reliable lifesaving tool in mixed overdoses. Catherine’s research confronts this problem head-on by asking: What actually happens to breathing when these two drugs collide? Mechanisms That Kill: The Double Hit to Breathing Using whole-body plethysmography and pulse oximetry, Catherine studies how mice respond to fentanyl, xylazine, and their combination. The results show a double assault on the respiratory cycle . Fentanyl, through the mu-opioid receptor, blunts the brainstem’s inspiratory drive so that each breath draws in less air. Xylazine, acting through alpha-2 adrenergic receptors, slows the expiratory phase, making it harder to clear air out. On their own, each drug weakens breathing. Together, they don’t just accumulate—they potentiate. “When I combined the two drugs, there was a potentiation of fentanyl’s effect on tidal volume—mice were bringing in even less air,” Catherine explains. This means overdose is not just about “slowed breathing.” It’s about a fundamental collapse of the cycle itself: one drug blocking air from entering, the other delaying its release. Why Oxygen Monitors Can Miss the Danger Perhaps the most unsettling part of Catherine’s work is the disconnect between breathing changes  and oxygen saturation . With fentanyl, the danger lies in apneas —complete pauses in breathing. Even if the respiratory rate doesn’t appear drastically lower, those pauses send oxygen levels plummeting. By contrast, xylazine causes pronounced slowing of the breathing rate but fewer apneas, which means oxygen saturation doesn’t always drop as quickly. This mismatch creates a dangerous blind spot. A patient might appear stable on an oxygen monitor, even as their breathing mechanics are deteriorating. For emergency responders, this insight is critical: oxygen saturation alone is not always a reliable measure of overdose severity, especially in polysubstance cases. Naloxone’s Limits in the Age of Xylazine For decades, naloxone has been the trusted antidote for opioid overdoses. By displacing opioids from the mu-opioid receptor, it restores breathing within minutes. But that mechanism has no impact on xylazine, which works through alpha-2 adrenergic receptors. The result is a growing number of cases where overdose victims respond partially to naloxone—they breathe a little better—but remain dangerously sedated, unresponsive, or relapse into respiratory depression. First responders describe revivals that don’t feel like revivals, as if the body is still trapped in a pharmacological fog. Without a reversal agent for xylazine, the best defense right now is mechanistic understanding . Catherine’s work lays the foundation for designing better interventions, from preclinical models to clinical practice. From Street Samples to Lab Models What makes Catherine’s research particularly powerful is how it stays connected to reality outside the lab. By collaborating with harm-reduction groups such as the Red Project in Grand Rapids , she ensures her models reflect the drugs people are actually using. Those groups are reporting alarming trends: in Grand Rapids alone, the number of fentanyl samples containing xylazine has risen 30 to 60 percent in just a year . That surge mirrors what’s happening nationally. For Catherine, those numbers aren’t just statistics—they’re signals guiding how to build better models of polysubstance exposure. The insight is simple but urgent: the drug supply evolves faster than medicine.  Without research that keeps pace, clinical tools will always be one step behind. Why This Research Matters Beyond the Lab Catherine’s findings bridge the gap between basic receptor biology and real-world overdose response. For scientists, they sharpen our understanding of how different GPCR systems interact to produce respiratory depression. For clinicians, they challenge the assumption that oxygen monitors and naloxone alone are sufficient for managing overdoses. And for policymakers, they make clear that public health strategies must address polysubstance exposure, not just fentanyl in isolation. In other words, this is GPCR science with immediate, life-or-death consequences. The Urgency Ahead Every overdose today is more complicated than the last. Breathing doesn’t fail in a single, predictable way—it collapses through overlapping pathways that no single drug can reverse. Monitoring tools miss critical warning signs. And the illicit supply is moving faster than clinical medicine can adjust. That is why Catherine’s work matters: it shows in mechanistic detail how fentanyl and xylazine change what overdose even means. By tracing those pathways, her research gives scientists, first responders, and policymakers the knowledge they need to adapt—before the death toll climbs even higher. “Fentanyl and xylazine aren’t just statistics. They’re rewriting the biology of overdose. The question now is whether science and public health can keep up.”