Vomeronasal receptor
| Vomeronasal receptor, type 1 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
 | |||||||||||
| Identifiers | |||||||||||
| Symbol | Vmron_rcpt_1 | ||||||||||
| Pfam | PF03402 | ||||||||||
| InterPro | IPR004072 | ||||||||||
| |||||||||||
| GPCR, family 3, vomeronasal receptor, type 2 | |
|---|---|
| Identifiers | |
| Symbol | GPCR_3_vmron_rcpt_2 |
| InterPro | IPR004073 |
Vomeronasal receptors are a class of
The VNO is present in most amphibia, reptiles and non-primate mammals but is absent in birds, adult catarrhine monkeys and apes.[2] 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. Two distinct families of vomeronasal receptors – which putatively function as pheromone receptors – have been identified in the vomeronasal organ (V1Rs and V2Rs). While all are G protein-coupled receptors (GPCRs), they are distantly related to the receptors of the main olfactory system, highlighting their different role.[1]
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.[3] 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 signaling.[1] A number of human V1 receptor homologues have also been found. The majority of these human sequences are pseudogenes,[4][5] but an apparently functional receptor has been identified that is expressed in the human olfactory system.[6]
The V2 receptors are members of GPCR family 3 and have close similarity to the extracellular calcium-sensing receptors.[7] Rodents appear to have around 100 functional V2 receptors and many pseudogenes.[8] These receptors are expressed in the basal regions of VNO, where they couple to G proteins to mediate inositol trisphosphate responses.[9] Homologues have also been identified in fish,[10] and the ligand specificity of one such receptor has been determined: a receptor from goldfish olfactory epithelium has been reported to bind basic amino acids, which are odorants for fish.[11]