An FTIR Study of Monkey Green- and Red-Sensitive Visual Pigments

摘要

Humans have two kinds of vision: twilight vision mediated by rhodopsin in rod photoreceptor cells and color vision achieved by multiple color pigments in cone photoreceptor cells. Humans have three color pigments: red-, green-, and blue-sensitive proteins maximally absorbing at 560, 530, and 425 nm, respectively, and specific perception of light by the red, green, blue (RGB) sensors is the origin of color vision. Rhodopsin and color-pigments both contain a common chromophore molecule, 11 -cis retinal, whereas different chromophore-protein interactions allow preferential absorption of different colors. On the molecular level, studying rhodopsin is highly advantageous because large amounts of protein can be obtained from vertebrate and invertebrate native cells. Consequently, X-ray structures of bovine and squid rhodopsins were determined. In the case of bovine rhodopsin, the structures have been further determined for photointermediates and for the active-state complexed with the C-terminus peptide of the a subunit of G-protein. These structures provided insights into the mechanism of the chromophore-protein interaction and activation. On the other hand, structural studies of color pigments lag far behind those of rhodopsin. In fact, none of color pigments was crystallized.