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From Proteopedia
Cryo-EM structure of the mmGPR4-Gs receptor in pH6.2
Structural highlights
FunctionGPR4_MOUSE Proton-sensing G-protein coupled receptor couples to multiple intracellular signaling pathways, including GNAS/cAMP, GNAQ/phospholipase C (PLC), and GNA12/GNA13/Rho pathways (PubMed:17145776). Acidosis-induced GPR4 activation increases paracellular gap formation and permeability of vascular endothelial cells through the GNA12/GNA13/Rho GTPase signaling pathway (PubMed:32058960). In the brain may mediate central respiratory sensitivity to CO(2)/H(+) (PubMed:26068853).[1] [2] [3] Publication Abstract from PubMedAnimals have evolved pH-sensing membrane receptors, such as G-protein-coupled receptor 4 (GPR4), to monitor pH changes related to their physiology and generate adaptive reactions. However, the evolutionary trajectory and structural mechanism of proton sensing by GPR4 remain unresolved. Here, we observed a positive correlation between the optimal pH of GPR4 activity and the blood pH range across different species. By solving 7-cryoelectron microscopy (cryo-EM) structures of Xenopus tropicalis GPR4 (xtGPR4) and Mus musculus GPR4 (mmGPR4) under varying pH conditions, we identified that protonation of H(ECL2-45.47) and H(7.36) enabled polar network establishment and tighter association between the extracellular loop 2 (ECL2) and 7 transmembrane (7TM) domain, as well as a conserved propagating path, which are common mechanisms underlying protonation-induced GPR4 activation across different species. Moreover, protonation of distinct extracellular H(ECL2-45.41) contributed to the more acidic optimal pH range of xtGPR4. Overall, our study revealed common and distinct mechanisms of proton sensing by GPR4, from a structural, functional, and evolutionary perspective. Evolutionary study and structural basis of proton sensing by Mus GPR4 and Xenopus GPR4.,Wen X, Shang P, Chen H, Guo L, Rong N, Jiang X, Li X, Liu J, Yang G, Zhang J, Zhu K, Meng Q, He X, Wang Z, Liu Z, Cheng H, Zheng Y, Zhang B, Pang J, Liu Z, Xiao P, Chen Y, Liu L, Luo F, Yu X, Yi F, Zhang P, Yang F, Deng C, Sun JP Cell. 2025 Feb 6;188(3):653-670.e24. doi: 10.1016/j.cell.2024.12.001. Epub 2025 , Jan 2. PMID:39753131[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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Categories: Large Structures | Mus musculus | Rong NK | Sun JP | Wen X | Yang F
