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== Function == | == Function == | ||
[https://www.uniprot.org/uniprot/GNAS2_HUMAN GNAS2_HUMAN] Guanine nucleotide-binding proteins (G proteins) function as transducers in numerous signaling pathways controlled by G protein-coupled receptors (GPCRs) (PubMed:17110384). Signaling involves the activation of adenylyl cyclases, resulting in increased levels of the signaling molecule cAMP (PubMed:26206488, PubMed:8702665). GNAS functions downstream of several GPCRs, including beta-adrenergic receptors (PubMed:21488135). Stimulates the Ras signaling pathway via RAPGEF2 (PubMed:12391161).<ref>PMID:12391161</ref> <ref>PMID:17110384</ref> <ref>PMID:21488135</ref> <ref>PMID:26206488</ref> <ref>PMID:8702665</ref> | [https://www.uniprot.org/uniprot/GNAS2_HUMAN GNAS2_HUMAN] Guanine nucleotide-binding proteins (G proteins) function as transducers in numerous signaling pathways controlled by G protein-coupled receptors (GPCRs) (PubMed:17110384). Signaling involves the activation of adenylyl cyclases, resulting in increased levels of the signaling molecule cAMP (PubMed:26206488, PubMed:8702665). GNAS functions downstream of several GPCRs, including beta-adrenergic receptors (PubMed:21488135). Stimulates the Ras signaling pathway via RAPGEF2 (PubMed:12391161).<ref>PMID:12391161</ref> <ref>PMID:17110384</ref> <ref>PMID:21488135</ref> <ref>PMID:26206488</ref> <ref>PMID:8702665</ref> | ||
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== Publication Abstract from PubMed == | |||
G-protein-coupled receptors (GPCRs) activate heterotrimeric G proteins by stimulating guanine nucleotide exchange in the Galpha subunit(1). To visualize this mechanism, we developed a time-resolved cryo-EM approach that examines the progression of ensembles of pre-steady-state intermediates of a GPCR-G-protein complex. By monitoring the transitions of the stimulatory G(s) protein in complex with the beta(2)-adrenergic receptor at short sequential time points after GTP addition, we identified the conformational trajectory underlying G-protein activation and functional dissociation from the receptor. Twenty structures generated from sequential overlapping particle subsets along this trajectory, compared to control structures, provide a high-resolution description of the order of main events driving G-protein activation in response to GTP binding. Structural changes propagate from the nucleotide-binding pocket and extend through the GTPase domain, enacting alterations to Galpha switch regions and the alpha5 helix that weaken the G-protein-receptor interface. Molecular dynamics simulations with late structures in the cryo-EM trajectory support that enhanced ordering of GTP on closure of the alpha-helical domain against the nucleotide-bound Ras-homology domain correlates with alpha5 helix destabilization and eventual dissociation of the G protein from the GPCR. These findings also highlight the potential of time-resolved cryo-EM as a tool for mechanistic dissection of GPCR signalling events. | |||
Time-resolved cryo-EM of G-protein activation by a GPCR.,Papasergi-Scott MM, Perez-Hernandez G, Batebi H, Gao Y, Eskici G, Seven AB, Panova O, Hilger D, Casiraghi M, He F, Maul L, Gmeiner P, Kobilka BK, Hildebrand PW, Skiniotis G Nature. 2024 May;629(8014):1182-1191. doi: 10.1038/s41586-024-07153-1. Epub 2024 , Mar 13. PMID:38480881<ref>PMID:38480881</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
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== References == | == References == | ||
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