Protein-coding gene in humans
OPN1LW is a gene on the X chromosome that encodes for long wave sensitive (LWS) opsin, or red cone photopigment.[5] It is responsible for perception of visible light in the yellow-green range on the visible spectrum (around 500-570nm).[6][7] The gene contains 6 exons with variability that induces shifts in the spectral range.[8] OPN1LW is subject to homologous recombination with OPN1MW, as the two have very similar sequences.[8] These recombinations can lead to various vision problems, such as red-green colourblindness and blue monochromacy.[9] The protein encoded is a G-protein coupled receptor with embedded 11-cis-retinal, whose light excitation causes a cis-trans conformational change that begins the process of chemical signalling to the brain.[10]