Genes and ligands for odorant, vomeronasal and taste receptors

The chemical senses (smell and taste) have evolved complex repertoires of chemosensory receptors — G-protein coupled receptors with a seven-transmembrane domain structure. In the mouse, ∼1,000 odorant receptors are dedicated to the conventional sense of smell, ∼300 vomeronasal receptors mediate the detection of chemical stimuli (such as pheromones) by the vomeronasal organ, and ∼40 taste receptors are implicated in bitter, sweet and umami taste. Nearly all receptor genes have now been identified as the result of genome sequencing, but few receptor–ligand interactions have been characterized. Targeted expression of the green fluorescent protein in chemosensory cells is a promising approach to achieve this objective.