Visual pigments are the light-absorbing molecules that mediate vision. They consist of an apoprotein, opsin, covalently linked to cis-retinal. N-glycosylated. O-glycosylated. Phosphorylated on some or all of the serine and threonine residues present in the C-terminal region. Belongs to the G-protein coupled receptor 1 family. Opsin subfamily. Medium-wave-sensitive opsin genes vary in number among individuals and, together with a single red pigment gene, reside in a head-to-tail tandem array within the X chromosome. In the GRCh38 reference genome assembly, there are 3 genes in tandem coding for identical proteins AC P04001, AC P0DN77 and P0DN78.