OPN3
Description
The OPN3 (opsin 3) is a protein-coding gene located on chromosome 1.
Opsin-3, also known as encephalopsin or panopsin, is a protein that, in humans, is encoded by the OPN3 gene. Alternative splicing of this gene results in multiple transcript variants encoding different protein isoforms.
== Function == Opsins are members of the G protein-coupled receptor superfamily. In addition to the visual opsins, mammals possess several photoreceptive non-visual opsins that are expressed in tissues outside the eye. The opsin-3 gene is strongly expressed in brain and testis and weakly expressed in liver, placenta, heart, lung, skeletal muscle, kidney, and pancreas. The gene is expressed in the skin and may also be expressed in the retina. The protein has the canonical features of a photoreceptive opsin protein, however in human skin, OPN3 is not photoreceptive and acts as a negative regulator of melanogenesis.
== Applications == When OPN3 analogues are expressed in neurons, activation by light inhibits neurotransmitter release. This makes these analogues useful tools for optogenetic silencing, a method to study the impact of specific neurons on brain function.
== References ==
== Further reading ==
This article incorporates text from the United States National Library of Medicine, which is in the public domain.
OPN3 is a G-protein coupled receptor that is activated by ultraviolet A (UVA) light in the skin. It binds to both 11-cis retinal and all-trans retinal. It regulates melanogenesis by inhibiting alpha-MSH-induced MC1R-mediated cAMP signaling, modulating calcium flux, regulating CAMK2 phosphorylation, and subsequently phosphorylating CREB, p38, ERK and MITF in response to blue light. It plays a role in melanocyte survival through regulating intracellular calcium levels and subsequent BCL2/RAF1 signaling. It also regulates apoptosis via cytochrome c release and subsequent activation of the caspase cascade. It is required for TYR and DCT blue light-induced complex formation in melanocytes. It is involved in keratinocyte differentiation in response to blue-light. It is required for the UVA-mediated induction of calcium and mitogen-activated protein kinase signaling resulting in the expression of MMP1, MMP2, MMP3, MMP9 and TIMP1 in dermal fibroblasts. It plays a role in light-mediated glucose uptake, mitochondrial respiration and fatty acid metabolism in brown adipocyte tissues. It may be involved in photorelaxation of airway smooth muscle cells, via blue-light dependent GPCR signaling pathways.
OPN3 is also known as ECPN, PPP1R116.
