The GPR68 is a proton-sensing receptor involved in pH homeostasis. A study revealed that in osteosarcoma cells and primary human osteoblast precursors which expression of GPR68 exhibit strong PH-dependent inositol phosphate formation.
H+-induced concentration-dependent stimulation of intracellular calcium mobilization in CHO-K1/GPR68/Gα15. The cells were loaded with Calcium-4 prior to stimulation with a GPR68 receptor agonist, H+. The intracellular calcium change was measured by FLIPR. The relative fluorescent units (RFU) were plotted against the log of the cumulative doses of H+ (Mean ± SD, n = 2). The EC50 of H+ on GPR68 co-expressing with Gα15 in CHO-K1 cells was pH 6.29 (n=1 test) and pH6.66 (n=2 test).