Probing the structures of G protein-coupled receptors with mass spectrometry-based techniques

Abstract

G protein-coupled receptors (GPCRs) are key molecules to regulate numerous physiological processes in the human body, and represent one of the largest protein families as targets for drug development for various human diseases. Understanding the structural basis for GPCR activation, signaling and regulatory mechanisms lays the foundation for structure-based drug design. Compared to X-ray crystallography and cryo-electron microscopy which mainly present static snapshots of protein structures, mass spectrometry (MS)-based structural analysis is able to yield complementary information on the conformational ensemble and dynamics of protein machineries and their interactions with ligands or other proteins. Analysis of GPCR structures with multiple MS-based techniques have facilitated the characterization of structural architecture and conformational dynamics of GPCR proteins complexed with specific ligands and/or downstream signaling partners. In this review, we introduce four MS techniques (chemical cross-linking MS, hydrogen/deuterium exchange MS, native MS and fast photochemical oxidation of proteins MS) and illustrate how they are implemented to probe the structures of GPCR proteins and signaling complexes.