Mammalian olfactory receptors: pharmacology, G protein coupling and desensitization.

The vertebrate olfactory system recognizes and discriminates between thousands of structurally diverse odorants. Detection of odorants in mammals is mediated by olfactory receptors (ORs), which comprise the largest superfamily of G protein-coupled receptors (GPCRs). Upon odorant binding, ORs couple to G proteins, resulting in an increase in intracellular cAMP levels and subsequent receptor signaling. In this review, we will discuss recently published studies outlining the molecular basis of odor discrimination, focusing on pharmacology, G protein activation, and desensitization of ORs. A greater understanding of the molecular mechanisms underlying OR activity may help in the discovery of agonists and antagonists of ORs, and of GPCRs with potential therapeutic applications.