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| Title | Structural basis and biased signaling of proton sensation by GPCRs mediated by extracellular histidine rearrangement. |
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| Journal, issue, pages | Mol Cell, Vol. 85, Issue 8, Page 1658-11673.e7, Year 2025 |
| Publish date | Apr 17, 2025 |
Authors | Lulu Guo / Kongkai Zhu / Ya-Ni Zhong / Mingxin Gao / Junyan Liu / Zhimin Qi / Zili Liu / Naikang Rong / Minghui Zhang / Dongfang Li / Qiyue Zhang / Gongming Yang / Xinxin Zhang / Mingyue Zhang / Ning Ding / Yu-Qi Ping / Zhao Yang / Peng Xiao / Ming Xia / Xiao Yu / Alatan Gaole / Jin-Peng Sun / Fan Yang / ![]() |
| PubMed Abstract | Proton sensing by G protein-coupled receptors (GPCRs) is crucial in many life activities. However, its underlying mechanism remains unclear. Here, we report 8 cryoelectron microscopy (cryo-EM) ...Proton sensing by G protein-coupled receptors (GPCRs) is crucial in many life activities. However, its underlying mechanism remains unclear. Here, we report 8 cryoelectron microscopy (cryo-EM) structures of human GPR4 and GPR68 at different pH values and in complex with Gs or Gq trimers or in apo state. Structural inspection, structure-based pKa calculations, and mutational and computational analyses revealed that protonation of two conserved extracellular histidines induced polar network formation and other conformational changes to tether 7-transmembrane (TM7) to second extracellular loop (ECL2), and these changes constitute the central mechanisms of proton-induced activation of GPR4 and GPR68. Unexpectedly, proton sensation by specific extracellular histidine determined biased G protein coupling of GPR4. Moreover, GPR68's additional pH-sensing H84 enhances its function in a more acidic optimal pH range. The propagation path connecting proton-sensing histidines to the toggle switch was characterized. Collectively, we provide structural insights into the proton sensing, activation, and downstream effector coupling mechanisms of proton-sensing GPCRs. |
External links | Mol Cell / PubMed:40215959 |
| Methods | EM (single particle) |
| Resolution | 3.2 Å |
| Structure data | EMDB-39757, PDB-8z3y: |
| Source |
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Keywords | MEMBRANE PROTEIN/IMMUNE SYSTEM / pH6.8 / hGPR4 / MEMBRANE PROTEIN / MEMBRANE PROTEIN-IMMUNE SYSTEM complex |
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homo sapiens (human)
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