|Vomeronasal receptor, type 1|
Pheromones have evolved in all animal phyla, to signal sex and dominance status, and are responsible for stereotypical social and sexual behaviour among members of the same species. In mammals, these chemical signals are believed to be detected primarily by the vomeronasal organ (VNO), a chemosensory organ located at the base of the nasal septum.
The VNO is present in most amphibia, reptiles and non-primate mammals but is absent in birds, adult catarrhine monkeys and apes. An active role for the human VNO in the detection of pheromones is disputed; the VNO is clearly present in the fetus but appears to be atrophied or absent in adults. Three distinct families of putative pheromone receptors have been identified in the vomeronasal organ (V1Rs, V2Rs and V3Rs). All are G protein-coupled receptors but are only distantly related to the receptors of the main olfactory system, highlighting their different role.
The V1 receptors share between 50 and 90% sequence identity but have little similarity to other families of G protein-coupled receptors. They appear to be distantly related to the mammalian T2R bitter taste receptors and the rhodopsin-like GPCRs. In rat, the family comprises 30-40 genes. These are expressed in the apical regions of the VNO, in neurons expressing Gi2. Coupling of the receptors to this protein mediates inositol trisphosphate signalling. A number of human V1 receptor homologues have also been found. The majority of these human sequences are pseudogenes  but an apparently functional receptor has been identified that is expressed in the human olfactory system.
Human proteins containing this domain
- Pantages E, Dulac C (Dec 2000). "A novel family of candidate pheromone receptors in mammals". Neuron 28 (3): 835–45. doi:10.1016/S0896-6273(00)00157-4. PMID 11163270.
- Keverne EB (Oct 1999). "The vomeronasal organ". Science 286 (5440): 716–20. doi:10.1126/science.286.5440.716. PMID 10531049.
- Josefsson LG (Nov 1999). "Evidence for kinship between diverse G-protein coupled receptors". Gene 239 (2): 333–40. doi:10.1016/S0378-1119(99)00392-3. PMID 10548735.
- Kouros-Mehr H, Pintchovski S, Melnyk J, Chen YJ, Friedman C, Trask B, Shizuya H (Nov 2001). "Identification of non-functional human VNO receptor genes provides evidence for vestigiality of the human VNO". Chemical Senses 26 (9): 1167–74. doi:10.1093/chemse/26.9.1167. PMID 11705802.
- Giorgi D, Friedman C, Trask BJ, Rouquier S (Dec 2000). "Characterization of nonfunctional V1R-like pheromone receptor sequences in human". Genome Research 10 (12): 1979–85. doi:10.1101/gr.10.12.1979. PMC 313059. PMID 11116092.
- Rodriguez I, Greer CA, Mok MY, Mombaerts P (Sep 2000). "A putative pheromone receptor gene expressed in human olfactory mucosa". Nature Genetics 26 (1): 18–9. doi:10.1038/79124. PMID 10973240.