OPN3

Opsin-3 also known as encephalopsin or panopsin^[4] is a protein that, in humans, is encoded by the OPN3 gene.^[5][6][7] Alternative splicing of this gene results in multiple transcript variants encoding different protein isoforms.^[8]

OPN3
Identifiers
Aliases	OPN3, ECPN, PPP1R116, opsin 3
External IDs	OMIM: 606695; MGI: 1338022; HomoloGene: 40707; GeneCards: OPN3; OMA:OPN3 - orthologs
Gene location (Mouse) Chr. Chromosome 1 (mouse)[1] Band 1|1 H3 Start 175,489,987 bp[1] End 175,520,342 bp[1]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in middle temporal gyrus placenta tibia Brodmann area 46 palpebral conjunctiva visceral pleura prefrontal cortex amniotic fluid Brodmann area 23 monocyte Top expressed in white adipose tissue vestibular membrane of cochlear duct motor neuron subcutaneous adipose tissue lateral geniculate nucleus medial geniculate nucleus secondary oocyte primary oocyte seminiferous tubule spinal ganglia More reference expression data BioGPS More reference expression data
Gene ontology Molecular function G protein-coupled receptor activity photoreceptor activity signal transducer activity G protein-coupled photoreceptor activity Cellular component integral component of membrane integral component of plasma membrane membrane photoreceptor outer segment Biological process G protein-coupled receptor signaling pathway regulation of circadian rhythm signal transduction response to stimulus detection of light stimulus detection of visible light phototransduction cellular response to light stimulus Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 23596 13603 Ensembl n/a ENSMUSG00000026525 UniProt Q9H1Y3 Q9WUK7 RefSeq (mRNA) NM_014322 NM_001030011 NM_001030012 NM_001381855 NM_001381856 NM_010098 RefSeq (protein) NP_055137 NP_001368784 NP_001368785 NP_034228 Location (UCSC) n/a Chr 1: 175.49 – 175.52 Mb PubMed search [2] [3]
Wikidata
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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^[8] and may also be expressed in the retina. The protein has the canonical features of a photoreceptive opsin protein,^[7] however in human skin, OPN3 is not photoreceptive and acts as a negative regulator of melanogenesis.^[9]

Applications

When OPN3 analogues are expressed in neurons, activation by light inhibits neurotransmitter release.^[10][11] This makes these analogues useful tools for optogenetic silencing, a method to study the impact of specific neurons on brain function.