Assembly of a GPCR-G Protein Complex
Assembly of a GPCR-G Protein Complex
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DOI：
10.1016/j.cell.2019.04.022
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发表时间：
2019-05-16
期刊：
影响因子：
64.5
通讯作者：
Chung, Ka Young
中科院分区：
文献类型：
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作者：
Du, Yang;Duc, Nguyen Minh;Chung, Ka Young
G蛋白偶联受体(GPCRs)激活G蛋白是激素和神经递质传递跨膜信号的基础。通过结晶学和低温电子显微镜(Cryo-EM)获得的GPCRs-G蛋白复合体的最新结构表明，GPCRs与不同G蛋白亚型的α亚基之间的相互作用相似。虽然观察到了一些G蛋白亚型特异性的差异，但对于G蛋白亚型选择性没有明确的结构解释。所有这些复合体都稳定在无核苷酸状态，这是活细胞中不存在的情况。为了更好地了解偶联特异性的结构基础，我们使用了时间分辨结构质谱学技术来研究GPCR-G蛋白复合体的形成和G蛋白的激活。我们的结果表明，偶联特异性由一个或多个瞬时中间状态决定，这些中间状态充当选择性过滤器，并先于晶体和低温EM结构中观察到的稳定的无核苷酸GPCR-G蛋白复合体的形成。
The activation of G proteins by G protein-coupled receptors (GPCRs) underlies the majority of transmembrane signaling by hormones and neurotransmitters. Recent structures of GPCR-G protein complexes obtained by crystallography and cryoelectron microscopy (cryo-EM) reveal similar interactions between GPCRs and the alpha subunit of different G protein isoforms. While some G protein subtype-specific differences are observed, there is no clear structural explanation for G protein subtype-selectivity. All of these complexes are stabilized in the nucleotide-free state, a condition that does not exist in living cells. In an effort to better understand the structural basis of coupling specificity, we used time-resolved structural mass spectrometry techniques to investigate GPCR-G protein complex formation and G-protein activation. Our results suggest that coupling specificity is determined by one or more transient intermediate states that serve as selectivity filters and precede the formation of the stable nucleotide-free GPCR-G protein complexes observed in crystal and cryo-EM structures.