Definition: Photosensitive protein complexes of varied light absorption properties which are expressed in the PHOTORECEPTOR CELLS. They are OPSINS conjugated with VITAMIN A-based chromophores. Chromophores capture photons of light, leading to the activation of opsins and a biochemical cascade that ultimately excites the photoreceptor cells.
not for deposition of pigments in the retina (= RETINITIS PIGMENTOSA)
ExamplesOpsins
Can J Zool 55(5):836;1976; Can J Zool 55(6):1000;1977; Gen Comp Endocrinol 26(2):233;1975; Photochem Photobiol 29(4):695;1979; Rev Can Biol 1979;38(3):185