转导素
视紫红质
生物
G蛋白偶联受体
G蛋白
GTP'
蛋白质亚单位
鸟嘌呤核苷酸交换因子
GTP结合蛋白调节剂
生物物理学
蛋白质结构
生物化学
细胞生物学
GTP酶
受体
视网膜
基因
酶
作者
Yang Gao,Hongli Hu,Sekar Ramachandran,Jon W. Erickson,Richard A. Cerione,Georgios Skiniotis
出处
期刊:Molecular Cell
[Elsevier]
日期:2019-07-09
卷期号:75 (4): 781-790.e3
被引量:80
标识
DOI:10.1016/j.molcel.2019.06.007
摘要
Rhodopsin (Rho), a prototypical G-protein-coupled receptor (GPCR) in vertebrate vision, activates the G-protein transducin (GT) by catalyzing GDP-GTP exchange on its α subunit (GαT). To elucidate the determinants of GT coupling and activation, we obtained cryo-EM structures of a fully functional, light-activated Rho-GT complex in the presence and absence of a G-protein-stabilizing nanobody. The structures illustrate how GT 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 GαT 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.
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