teleost multiple tissue (tmt) opsin, member of the class A family of seven-transmembrane G protein-coupled receptors
Teleost multiple tissue (tmt) opsins are homologs of encephalopsin. Mouse encephalopsin (or panopsin) is highly expressed in the brain and testes, whereas the teleost homologs are localized to multiple tissues. The exact functions of the encephalopsins and tmt-opsins are unknown. The vertebrate non-visual opsin family includes pinopsins, parapinopsin, VA (vertebrate ancient) opsins, and parietopsins. These non-visual opsins are expressed in various extra-retinal tissues and/or in non-rod, non-cone retinal cells. They are thought to be involved in light-dependent physiological functions such as photo-entrainment of circadian rhythm, photoperiodicity and body color change. Tmt opsins belong to the class A of the G protein-coupled receptors and show strong homology to the vertebrate visual opsins.