Figure 3. Tuning OR51E2 odorant selectivity.

a,b) OR51E2 responds selectively to the short chain fatty acids acetate and propionate as measured by a cAMP production assay. c) Docked poses of octanoate (C8) and hexanoate (C6) are shown in the predicted binding cavities of homology modeled OR51E2 mutants F155^4x57A and L158^4x60A. Binding pocket cavities are shown as gray surface. Replacement of F155^4x57 and L158^4x60 with alanine is predicted to yield a binding pocket with increased volume capable of accommodating longer chain fatty acids. d) The F155^4x57A and L158^4x60A mutations in OR51E2 lead to increased sensitivity to long chain fatty acids. Conversely, the potency for acetate and propionate is reduced for these two mutants. Data points in b and d are mean ± standard deviation from n = 4 experiments.