Melanopsin

OPN4
Identifiers
Aliases	OPN4, MOP, opsin 4
External IDs	OMIM: 606665 MGI: 1353425 HomoloGene: 69152 GeneCards: OPN4
Gene ontology Molecular function • 11-cis retinal binding • G-protein coupled photoreceptor activity • G-protein coupled receptor activity • photoreceptor activity • signal transducer activity Cellular component • integral component of membrane • plasma membrane • membrane • integral component of plasma membrane Biological process • protein-chromophore linkage • G-protein coupled receptor signaling pathway • regulation of circadian rhythm • signal transduction • visual perception • rhodopsin mediated signaling pathway • rhythmic process • phototransduction • response to stimulus • cellular response to light stimulus Sources:Amigo / QuickGO
Orthologs
Species	Human	Mouse
Entrez	94233	30044
Ensembl	ENSG00000122375	ENSMUSG00000021799
UniProt	Q9UHM6	Q9QXZ9
RefSeq (mRNA)	NM_033282 NM_001030015	NM_001128599 NM_013887
RefSeq (protein)	NP_001025186 NP_150598	NP_001122071.1 NP_038915.1
Location (UCSC)	Chr 10: 86.65 – 86.67 Mb	Chr 14: 34.59 – 34.6 Mb
PubMed search

94233

30044

ENSG00000122375

ENSMUSG00000021799

Q9UHM6

Q9QXZ9

NM_033282
NM_001030015

NM_001128599
NM_013887

NP_001025186
NP_150598

NP_001122071.1
NP_038915.1

Melanopsin is a type of photopigment belonging to a larger family of light-sensitive retinal proteins called opsins and encoded by the gene Opn4. In the mammalian retina, there are two additional opsins, both involved in the formation of visual images: rhodopsin and photopsin (types I, II, and III) in the rod and cone photoreceptor cells, respectively.

In humans, melanopsin is found in intrinsically photosensitive retinal ganglion cells (ipRGCs). It is also found in the iris of mice and primates. Melanopsin is also found in rats, amphioxus, and other chordates. ipRGCs are photoreceptor cells which are particularly sensitive to the absorption of short-wavelength (blue) visible light and communicate information directly to the area of the brain called the suprachiasmatic nucleus (SCN), also known as the central "body clock", in mammals. Melanopsin plays an important non-image-forming role in the setting of circadian rhythms as well as other functions. Mutations in the Opn4 gene can lead to clinical disorders, such as Seasonal Affective Disorder (SAD). According to one study, melanopsin has been found in eighteen sites in the human brain (outside of the retinohypothalamic tract), intracellularly, in a granular pattern, in the cerebral cortex, the cerebellar cortex and several phylogenetically old regions, primarily in neuronal soma, not in nuclei. Melanopsin is also expressed in human cones. However, only 0.11% to 0.55% of human cones express melanopsin and are exclusively found in the peripheral regions of the retina. The human peripheral retina senses light at high intensities that is best explained by four different photopigment classes.

...
Wikipedia