Protein networks and their dynamic regulation play a fundamental role in biological systems. Seven transmembrane-spanning G protein-coupled receptors (GPCRs) constitute the largest family of membrane receptors controlling the flow of information from the extracellular environment into cells by inducing intracellular signaling pathways. Several GPCR-associated protein complexes (GAPCs), particularly those binding to the intracellular carboxyl-terminus (C-terminus), have been identified over the last 20 years. Recent optimizations in purification protocols and advances in mass spectrometry-based protein identification techniques have considerably accelerated the identification of GAPCs. We will concentrate here on a description of the latest version of the peptide affinity purification approach dedicated to the purification of GAPCs interacting with GPCR C-termini or any other soluble receptor subdomain.
