Techniques for the discovery of GPCR-associated protein complexes

Biosynthesis and function of G protein-coupled receptors (GPCR) are accompanied by multiple GPCR-associated protein complexes. Despite considerable sequence diversity, all GPCRs are assumed to share a common 7-transmembrane-spanning architecture giving rise to an extracellular, intracellular, and transmembrane interface for the interaction with protein partners recognizing either linear or structural receptor epitopes. Different purification techniques have been developed in the past to identify GPCR-associated proteins other than classically known interacting proteins like heterotrimeric G proteins and β-arrestins. These techniques use either entire receptors or receptor subdomains as baits. We are presenting here two proteomic approaches developed in our laboratory to purify protein complexes interacting either with receptor subdomains from cell or tissue lysates or with entire receptors from intact cells.