Molecular mechanism of activation of human musk receptors OR5AN1 and OR1A1 by ( R )-muscone and diverse other musk-smelling compounds

Significance While natural musk has been used for 2,000 years in perfumery, and in traditional medicine for its cardioprotective effects, its mode of activating odorant receptors (ORs) is unknown. ORs, G protein-coupled receptors (GPCRs), which constitute 40% of all pharmacophore receptors, are also expressed in nonolfactory tissues. Understanding the activation of ORs at the molecular level is challenging due to lack of crystallographic models. By combining site-directed mutagenesis with computational studies of human musk ORs involving 35 chiral and achiral muscone analogues, we propose structural models, including binding site prediction and responsible amino acid residues identification. Our studies of musk-responsive ORs should assist the study of the pharmacological effects of musks involving non-OR GPCRs.