Differences in (−)citronellal binding to various odorant receptors

To test the hypothesis that olfactory receptors (ORs) recognize different molecular features of odor molecules termed “odotypes”, we studied receptor–ligand interactions of two human and two mouse ORs, recognizing (−)citronellal. Structurally similar receptors provide identical binding pockets (OLFR43, OR1A1, and OR1A2), and have comparable EC50 values. Other ORs with lower sequence identity bind (−)citronellal in a different way, leading to different EC50 values.