Funding Organization(s): National Institutes of Health/National Cancer Institute (NIH/NCI), National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS), National Institutes of Health/National Institute of Neurological Disorders and Stroke (NIH/NINDS)
Primary Citation of Related Structures: 6OY9, 6OYA
PubMed Abstract:
Rhodopsin (Rho), a prototypical G-protein-coupled receptor (GPCR) in vertebrate vision, activates the G-protein transducin (G T ) by catalyzing GDP-GTP exchange on its α subunit (Gα T ). To elucidate the determinants of G T coupling and activation, we obtained cryo-EM structures of a fully functional, light-activated Rho-G T complex in the presence and absence of a G-protein-stabilizing nanobody ...
Rhodopsin (Rho), a prototypical G-protein-coupled receptor (GPCR) in vertebrate vision, activates the G-protein transducin (G T ) by catalyzing GDP-GTP exchange on its α subunit (Gα T ). To elucidate the determinants of G T coupling and activation, we obtained cryo-EM structures of a fully functional, light-activated Rho-G T complex in the presence and absence of a G-protein-stabilizing nanobody. The structures illustrate how G T overcomes its low basal activity by engaging activated Rho in a conformation distinct from other GPCR-G-protein complexes. Moreover, the nanobody-free structures reveal native conformations of G-protein components and capture three distinct conformers showing the Gα T helical domain (αHD) contacting the Gβγ subunits. These findings uncover the molecular underpinnings of G-protein activation by visual rhodopsin and shed new light on the role played by Gβγ during receptor-catalyzed nucleotide exchange.
Organizational Affiliation:
Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA. Electronic address: yiorgo@stanford.edu.
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