Figure 1. Olfr78 was found to respond to acetate and propionate, but not any other ligands tested, including other mono- or di-carboxylic acids (A). Dose-response curves for Olfr78 (B) and it’s human ortholog, OR51E2 (C) indicate that both receptors are slightly more responsive to propionate than to acetate, with EC₅₀ values in the high µM-low mM range (Olfr78: EC₅₀ = 2.35 mM for acetate and 0.92 mM for propionate; OR51E2: EC₅₀ = 2.93 mM for acetate and 2.16 mM for propionate). Figure modified from reference 18.