Abstract
G-protein coupled receptors (GCR) have been cloned from olfactory, vomeronasal and taste organs. Roles of these receptors in these organs are discussed. Olfactory and gustatory responses are induced via cAMP-dependent pathway, IP3-dependent pathway and second messenger-independent pathway. A single olfactory cell responds to various species of odorants, although a single olfactory cell has only one type of GCR. The responses of mammalian vomeronasal receptor cells to pheromones are induced via IP3. A single rat vomeronasal receptor cell responds only to one species of urine which contains pheromones. The receptor mechanisms of sweet, bitter and umami substances are discussed.
