Structural basis of G protein-coupled receptor-G protein interactions.
The interaction of G protein-coupled receptors (GPCRs) with heterotrimeric G proteins represents one of the most fundamental biological processes. However, the molecular architecture of the GPCR-G protein complex remains poorly defined. In the present study, we applied a comprehensive GPCR-G protein alpha subunit (Galpha) chemical cross-linking strategy to map a receptor-Galpha interface, both before and after agonist-induced receptor activation. Using the M(3) muscarinic acetylcholine receptor (M3R)-Galpha(q) system as a model system, we examined the ability of approximately 250 combinations of cysteine-substituted M3R and Galpha(q) proteins to undergo cross-link formation. We identified many specific M3R-Galpha(q) contact sites, in both the inactive and active receptor conformations, allowing us to draw conclusions regarding the basic architecture of the M3R-Galpha(q) interface and the nature of the conformational changes following receptor activation. As heterotrimeric G proteins as well as most GPCRs share a high degree of structural homology, our findings should be of broad general relevance.
Hu
Jianxin
J
Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA. jianxinh@niddk.nih.gov
Wang
Yan
Y
Zhang
Xiaohong
X
Lloyd
John R
JR
Li
Jian Hua
JH
Karpiak
Joel
J
Costanzi
Stefano
S
Wess
Jürgen
J
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D044385:GTP-Binding Protein alpha Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D047468:Immunoprecipitation; D013058:Mass Spectrometry; D008958:Models, Molecular; D009154:Mutation; D011485:Protein Binding; D011487:Protein Conformation; D011976:Receptors, Muscarinic / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D044385:GTP-Binding Protein alpha Subunits; D011976:Receptors, Muscarinic