Galés C, Van Durm JJJ, Schaak S, Pontier S, Percherancier Y, Audet M, Paris H, Bouvier M. Probing the activation-promoted structural rearrangements in preassembled receptor-G protein complexes.
Nat Struct Mol Biol 2006;
13:778-86. [PMID:
16906158 DOI:
10.1038/nsmb1134]
[Citation(s) in RCA: 341] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Accepted: 07/21/2006] [Indexed: 12/12/2022]
Abstract
Activation of heterotrimeric G proteins by their cognate seven transmembrane domain receptors is believed to involve conformational changes propagated from the receptor to the G proteins. However, the nature of these changes remains unknown. We monitored the conformational rearrangements at the interfaces between receptors and G proteins and between G protein subunits by measuring bioluminescence resonance energy transfer between probes inserted at multiple sites in receptor-G protein complexes. Using the data obtained for the alpha(2A)AR-G alpha(i1) beta1gamma2 complex and the available crystal structures of G alpha(i1) beta1gamma2, we propose a model wherein agonist binding induces conformational reorganization of a preexisting receptor-G protein complex, leading the G alpha-G betagamma interface to open but not dissociate. This conformational change may represent the movement required to allow nucleotide exit from the G alpha subunit, thus reflecting the initial activation event.
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