OPN5
Description
The OPN5 (opsin 5) is a protein-coding gene located on chromosome 6.
OPN5 (Opsin-5) is a protein encoded by the OPN5 gene in humans. It's a member of the opsin family of G protein-coupled receptors and is a photoreceptor protein sensitive to ultraviolet (UV) light. OPN5 was discovered in mouse and human genomes and its mRNA expression was also found in neural tissues. Neuropsin is bistable at 0 °C and activates a UV-sensitive, heterotrimeric G protein Gi-mediated pathway in mammalian and avian tissues. Human neuropsin is expressed in the eye, brain, testes, and spinal cord. It belongs to the seven-exon subfamily of mammalian opsin genes that includes peropsin (RRH) and retinal G protein coupled receptor (RGR). Neuropsin has different isoforms created by alternative splicing. When reconstituted with 11-cis-retinal, mouse and human neuropsins absorb maximally at 380 nm. When illuminated these neuropsins are converted into blue-absorbing photoproducts (470 nm), which are stable in the dark.
OPN5, also known as Neuropsin, is a G protein-coupled receptor that is activated by ultraviolet A (UVA) light in the retina. It preferentially binds the chromophore 11-cis retinal and is a bistable protein that displays emission peaks at 380 nm (UVA light) and 470 nm (blue light). OPN5 is required for the light-response in the inner plexiform layer and contributes to the regulation of the light-response in the nerve fiber layer, via phosphorylated DAT/SLC6A3 dopamine uptake. OPN5 is involved in local corneal and retinal circadian rhythm photoentrainment via modulation of the UVA light-induced phase-shift of the retina clock. It also acts as a circadian photoreceptor in the outer ear, modulating circadian clock-gene expression in response to violet light during the light-to-dark transition phase and night phase of the circadian cycle. OPN5 is required in the retina to negatively regulate hyaloid vessel regression during postnatal development via light-dependent OPN5-SLC32A1-DRD2-VEGFR2 signaling. Finally, OPN5 is involved in the light-dependent regulation of retina and vitreous compartment dopamine levels.
OPN5 is also known as GPR136, GRP136, PGR12, TMEM13.
