The human<unk>  gene,<unk> , is expressed in ipRGCs, which comprises only 1-2% of RGCs in the inner mammalian retina, as studied by Samer Hattar and colleagues. The gene spans approximately 11.8 kb and is mapped to the long arm of chromosome 10. The gene includes nine introns and ten exons compared to the four to seven exons typically found in other human opsins. In non-mammalian vertebrates,<unk>  is found in a wider subset of retinal cells, as well as in photosensitive structures outside the retina, such as the iris muscle of the eye, deep brain regions, the pineal gland, and the skin. Paralogs of<unk>  include OPN1LW, OPN1MW, RHO and OPN3 and were discovered by the Genome Project.<unk> , like all other animal opsins (e.g. rhodopsin), is a member of the G-protein coupled receptor (GPCR) family. The<unk>  protein has seven alpha helices integrated in the plasma membrane, an N-terminal domain and a C-terminal domain. It resembles invertebrate opsins far more than vertebrate photopigments, especially in its amino acid sequence and downstream signaling cascade. Like invertebrate opsins, it appears to be a photopigment with intrinsic photoisomerase activity and signals through a G-protein of the Gq family.<unk>  uses a G(q) signaling pathway used by rhabdomeric opsins, in contrast to the G(t) pathway used by rods and cones. This suggests that<unk>  is a rhabdomeric, rather than ciliary, opsin.
Melanopsin
Neuropeptide
Neuropil
Agouti-related peptide
Autochaperone
Bryostatin
Neurohormone
Proopiomelanocortin