The OPN5 gene 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.

Neuropsin belongs to the seven-exon subfamily of mammalian opsin genes that includes peropsin (RRH) and retinal G protein coupled receptor (RGR).

However, neuropsin orthologs have only been experimentally verified in a small number of animals, among them human, mouse (Mus musculus),[5] chicken (Gallus gallus domesticus),[9][12] the Japanese quail (Coturnix japonica),[13] the European brittle star Amphiura filiformis (related to starfish),[10] the tardigrade water bear (Hypsibius dujardini),[14] and the tadpole of Xenopus laevis.

[15] Searches of publicly available databases of genetic sequences have found putative neuropsin orthologs in both major branches of Bilateria: protostomes and deuterostomes.

Among protostomes, putative neuropsins have been found in the molluscs owl limpet (Lottia gigantea) (a species of sea snail) and Pacific oyster (Crassostrea gigas), in the water flea (Daphnia pulex) (an arthropod), and in the annelid worm Capitella teleta.

[11] This article incorporates text from the United States National Library of Medicine, which is in the public domain.