Odorant Receptors: An Introduction to Teleost Odor-Coding GPCRs

The perception and discrimination of thousands of different odorants by the vertebrate olfactory system is unrivaled in terms of molecular complexity and involves activation of specific odorant receptors. A variety of olfactory receptor gene families are reported in teleost, all of which are the G-protein coupled receptors. The distribution of odorant receptors is uneven through the olfactory epithelium. Distinct odorant receptor neurons (ORNs) possess individual type of odorant receptor linked to specific G-proteins and activated in an odorant specific manner. Though teleost lack a vomeronasal organ yet the respective mammalian receptor homologs are expressed by one of the specialized types of ORN present in the olfactory epithelium. The gene repertoire sizes and their evolution vary greatly between the different odorant receptor gene families. This review foregathers the information on teleost odorant receptor repertoires, the spatial distribution of olfactory receptor neurons and their signal conveying mechanisms to the telencephalon.