Conformational Dynamics of Activation for the Pentameric Complex of Dimeric G Protein-Coupled Receptor and Heterotrimeric G Protein

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• 作者：Tivadar Orban¹ ; Beata Jastrzebska¹ ; Sayan Gupta² ; Benlian Wang² ; Masaru Miyagi² ; Mark  ; R. Chance² ; ^{mark.chance@case.edu} ; Krzysztof Palczewski¹ ; ^{kxp65@case.edu}
• 刊名：Structure
• 出版年：2012
• 期刊代码：143_09692126
• 类别：bio
• 出版时间：9 May, 2012
• 卷：20
• 期：5
• 页码：826-840
• 文件大小：2394 K

摘要

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Summary

Photoactivation of rhodopsin (Rho), a G protein-coupled receptor, causes conformational changes that provide a specific binding site for the rod G protein, G_t. In this work we employed structural mass spectrometry techniques to elucidate the structural changes accompanying transition of ground state Rho to photoactivated Rho (Rho^{鈭?/sup>) and in the pentameric complex between dimeric Rho鈭?/sup> and heterotrimeric G_t. Observed differences in hydroxyl radical labeling and deuterium uptake between Rho鈭?/sup> and the (Rho鈭?/sup>)₂-G_t complex suggest that photoactivation causes structural relaxation of Rho following its initial tightening upon G_t coupling. In contrast, nucleotide-free G_t in the complex is significantly more accessible to deuterium uptake allowing it to accept GTP and mediating complex dissociation. Thus, we provide direct evidence that in the critical step of signal amplification, Rho鈭?/sup> and G_t exhibit dissimilar conformational changes when they are coupled in the (Rho鈭?/sup>)₂-G_t complex.}