Table 1 Tetrapoda opsins and their functions. Subfamilies characterization according to [5, 12, 78] and [4]
From: Adaptive genomic evolution of opsins reveals that early mammals flourished in nocturnal environments
Subfamily | Opsins | Functions |
|---|---|---|
Visual opsins | RH1 RH2 OPN1sw1 OPN1sw2 OPN1lw | Rhodopsin mediates vision in dim-light whereas conopsins are responsible for colour vision. OPN1lw is sensitive to red-green or long-wavelengths, RH2 to green or middle wavelengths and two short-wave conopsins (OPN1sw2 and OPN1sw1) respond to blue-violet or violet-ultraviolet wavelengths, respectively. |
Non-visual opsins (sensu stricto) | OPN3 TMT TMT2 | TMT (teleost-multiple-tissue) are expressed in the liver, kidney and heart as well as eye and brain. Phylogenetic analysis reveals that it clades with OPN3, which also exhibits a multiple patterns of tissue expression. |
Pineal opsins | PARA PARIE PIN VA | Multiple opsins (PARA, PARIE, PIN) have been isolated from the parapineal complex. VA opsin is also expressed in the retina and was shown that forms a functional photopigment sensitive in the 460–480 nm range. |
Photoisomerases and Neuropsins | OPN5 RGR RRH | RGR and RRH have a probable role as all-trans retinal photoisomerases. OPN5 shows an absorption maximum at 380 nm and is thus UV-sensitive. |
Melanopsins | OPN4x OPN4m | Melanopsins are involved in circadian rhythm regulation and pupillary light reflexes. |