美国加州大学Aashish Manglik和Willow Coyote-Maestas共同合作，近期取得重要工作进展。他们研究提出了G蛋白偶联受体质子传感的分子基础。相关研究成果2025年1月2日在线发表于《细胞》杂志上。
据介绍，三种质子感应G蛋白偶联受体（GPCR），包括GPR4、GPR65和GPR68，对细胞外pH值有反应，以调节不同的生理学。质子如何激活这些受体尚不清楚。
研究人员鉴定了每个受体的冷冻电镜（cryo-EM）结构，以了解质子传感残基的空间排列。使用深度突变扫描（DMS），研究人员通过产生9500个突变体并测量它们对信号传导和表面表达的影响，确定了GPR68激活中每个残基的功能重要性。恒定pH分子动力学模拟为关键残基的构象景观和质子化模式提供了见解。这种无偏见的方法表明，与其他质子敏感通道和受体不同，没有一个位点对质子识别至关重要。相反，一个可滴定残基网络从细胞外表面延伸到跨膜区，聚集在规范基序上以激活质子传感GPCR。
总之，这一研究方法整合了结构、模拟和无偏函数询问，为理解GPCR信号复杂性提供了一个框架。
附：英文原文
Title: Molecular basis of proton sensing by G protein-coupled receptors
Author: Matthew K. Howard, Nicholas Hoppe, Xi-Ping Huang, Darko Mitrovic, Christian B. Billesblle, Christian B. Macdonald, Eshan Mehrotra, Patrick Rockefeller Grimes, Donovan D. Trinidad, Lucie Delemotte, Justin G. English, Willow Coyote-Maestas, Aashish Manglik
Issue&Volume: 2025-01-02
Abstract: Three proton-sensing G protein-coupled receptors (GPCRs)—GPR4, GPR65, and GPR68—respond to extracellular pH to regulate diverse physiology. How protons activate these receptors is poorly understood. We determined cryogenic-electron microscopy (cryo-EM) structures of each receptor to understand the spatial arrangement of proton-sensing residues. Using deep mutational scanning (DMS), we determined the functional importance of every residue in GPR68 activation by generating ～9,500 mutants and measuring their effects on signaling and surface expression. Constant-pH molecular dynamics simulations provided insights into the conformational landscape and protonation patterns of key residues. This unbiased approach revealed that, unlike other proton-sensitive channels and receptors, no single site is critical for proton recognition. Instead, a network of titratable residues extends from the extracellular surface to the transmembrane region, converging on canonical motifs to activate proton-sensing GPCRs. Our approach integrating structure, simulations, and unbiased functional interrogation provides a framework for understanding GPCR signaling complexity.
DOI: 10.1016/j.cell.2024.11.036
Source: https://www.cell.com/cell/abstract/S0092-8674(24)01373-4