Olfactory receptor (PubMed:27226631, PubMed:29249973). Activated by the odorant, beta-ionone, a synthetic terpenoid (PubMed:19389702, PubMed:27226631, PubMed:29249973). The activity of this receptor is probably mediated by G-proteins leading to the elevation of intracellular Ca(2+), cAMP and activation of the protein kinases PKA and MAPK3/MAPK1 (PubMed:27226631, PubMed:29249973). Stimulation of OR51E2 by beta-ionone affects melanocyte proliferation, differentiation, and melanogenesis (PubMed:27226631). Activation of OR51E2 by beta-ionone increases proliferation and migration of primary retinal pigment epithelial (RPE) cells (PubMed:29249973). 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 (PubMed:23401498). May also be activated by steroid hormones and regulate cell proliferation (PubMed:19389702). Activated by L-lactate in glomus cells (By similarity).