G-protein-coupled receptors (GPCRs) are essential components of the signalling network throughout the body. To understand the molecular mechanism of G-protein-mediated signalling, solved structures of receptors in inactive conformations and in the active conformation coupled to a G protein are necessary ...
G-protein-coupled receptors (GPCRs) are essential components of the signalling network throughout the body. To understand the molecular mechanism of G-protein-mediated signalling, solved structures of receptors in inactive conformations and in the active conformation coupled to a G protein are necessary. Here we present the structure of the adenosine A(2A) receptor (A(2A)R) bound to an engineered G protein, mini-Gs, at 3.4 Å resolution. Mini-Gs binds to A(2A)R through an extensive interface (1,048 Å2) that is similar, but not identical, to the interface between Gs and the β2-adrenergic receptor. The transition of the receptor from an agonist-bound active-intermediate state to an active G-protein-bound state is characterized by a 14 Å shift of the cytoplasmic end of transmembrane helix 6 (H6) away from the receptor core, slight changes in the positions of the cytoplasmic ends of H5 and H7 and rotamer changes of the amino acid side chains Arg3.50, Tyr5.58 and Tyr7.53. There are no substantial differences in the extracellular half of the receptor around the ligand binding pocket. The A(2A)R-mini-Gs structure highlights both the diversity and similarity in G-protein coupling to GPCRs and hints at the potential complexity of the molecular basis for G-protein specificity.
Related Citations:
Agonist-Bound Adenosine A2A Receptor Structures Reveal Common Features of Gpcr Activation Lebon, G., Warne, T., Edwards, P.C., Bennett, K., Langmead, C.J., Leslie, A.G.W., Tate, C.G. (2011) Nature 474: 521
Engineering a minimal G protein to facilitate crystallisation of G protein-coupled receptors in their active conformation. Carpenter, B., Tate, C.G. (2016) Protein Eng Des Sel 29: 583
Organizational Affiliation:
Institute of Biochemistry, Heinrich-Heine University Düsseldorf, 40225 Düsseldorf, Germany. Electronic address: lutz.schmitt@hhu.de.
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