The Odorant Signaling Pathway

Through the sense of smell mammals can obtain information about food, danger, sexual partners and predators. Two main different types of signals can be recognized by the olfactory system: volatile odorants, which are detected by the olfactory sensory neurons of the nose; and pheromones, which are detected by the vomeronasal neurons of the accessory olfactory system, or vomeronasal organ. These sensory neurons express respectively hundreds of odorant and pheromone receptors, which belong to the superfamily of G protein-coupled receptors. We review the general organization of the main and accessory olfactory systems, the structures of the receptor families in each of these organs and their signaling pathways.