Olfactory receptor. Activated by the odorant, beta-ionone, a synthetic terpenoid. The activity of this receptor is propably mediated by G-proteins leading to the elevation of intracellular Ca(2+), cAMP and activation of the protein kinases PKA and MAPK3/MAPK1. Stimulation of OR51E2 by beta-ionone affects melanocyte proliferation, differentiation, and melanogenesis. Activation of OR51E2 by beta-ionone increases proliferation and migration of primary retinal pigment epithelial (RPE) cells. Activated also by the short-chain fatty acids (SCFA) acetate and propionate. In response to SCFA, may positively regulate renin secretion and increase blood pressure. May also be activated by steroid hormones and regulate cell proliferation. Activated by L-lactate in glomus cells.