6cmo
Rhodopsin-Gi complexRhodopsin-Gi complex
Structural highlights
Function[GBG2_BOVIN] Guanine nucleotide-binding proteins (G proteins) are involved as a modulator or transducer in various transmembrane signaling systems. The beta and gamma chains are required for the GTPase activity, for replacement of GDP by GTP, and for G protein-effector interaction. [C562_ECOLX] Electron-transport protein of unknown function. [GBB1_RAT] Guanine nucleotide-binding proteins (G proteins) are involved as a modulator or transducer in various transmembrane signaling systems. The beta and gamma chains are required for the GTPase activity, for replacement of GDP by GTP, and for G protein-effector interaction. [GNAI1_HUMAN] Guanine nucleotide-binding proteins (G proteins) are involved as modulators or transducers in various transmembrane signaling systems. The G(i) proteins are involved in hormonal regulation of adenylate cyclase: they inhibit the cyclase in response to beta-adrenergic stimuli. The inactive GDP-bound form prevents the association of RGS14 with centrosomes and is required for the translocation of RGS14 from the cytoplasm to the plasma membrane. May play a role in cell division.[1] [2] Publication Abstract from PubMedG-protein-coupled receptors comprise the largest family of mammalian transmembrane receptors. They mediate numerous cellular pathways by coupling with downstream signalling transducers, including the hetrotrimeric G proteins Gs (stimulatory) and Gi (inhibitory) and several arrestin proteins. The structural mechanisms that define how G-protein-coupled receptors selectively couple to a specific type of G protein or arrestin remain unknown. Here, using cryo-electron microscopy, we show that the major interactions between activated rhodopsin and Gi are mediated by the C-terminal helix of the Gi alpha-subunit, which is wedged into the cytoplasmic cavity of the transmembrane helix bundle and directly contacts the amino terminus of helix 8 of rhodopsin. Structural comparisons of inactive, Gi-bound and arrestin-bound forms of rhodopsin with inactive and Gs-bound forms of the beta2-adrenergic receptor provide a foundation to understand the unique structural signatures that are associated with the recognition of Gs, Gi and arrestin by activated G-protein-coupled receptors. Cryo-EM structure of human rhodopsin bound to an inhibitory G protein.,Kang Y, Kuybeda O, de Waal PW, Mukherjee S, Van Eps N, Dutka P, Zhou XE, Bartesaghi A, Erramilli S, Morizumi T, Gu X, Yin Y, Liu P, Jiang Y, Meng X, Zhao G, Melcher K, Ernst OP, Kossiakoff AA, Subramaniam S, Xu HE Nature. 2018 Jun;558(7711):553-558. doi: 10.1038/s41586-018-0215-y. Epub 2018 Jun, 13. PMID:29899450[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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