unexpected discovery: phospholipids embedded inside each transmembrane bundle that appear to function as both structural work identified a quartet of charged residues - salt bridges between TM3 and TM5 helices of both spectrometry in collaboration with colleagues at UC Davis, they identified the exact molecular identity of both Both lipids form extensive contacts with their respective subunits, leading Fan to propose they are necessary confers analgesia through G protein signaling while avoiding the respiratory depression associated with beta-arrestin

For example, you might take the extracellular and transmembrane domains of the beta-2 adrenergic receptor