Proton-sensing_G_protein-coupled_receptors
Proton-sensing G protein-coupled receptors are transmembrane receptors which sense acidic pH and include GPR132 (G2A), GPR4, GPR68 (OGR1) and GPR65 (TDAG8).[2] These G protein-coupled receptors are activated when extracellular pH falls into the range of 6.4-6.8 (typical values are above 7.0). The functional role of the low pH sensitivity of the proton-sensing G protein-coupled receptors is being studied in several tissues where cells respond to conditions of low pH including bone and inflamed tissues. The four known proton-sensing G protein-coupled receptors are Class A receptors in subfamily A15.