Design, chemical synthesis, and expression of genes for the three human color vision pigments

Color vision in humans is mediated by three pigments from retinal cone photoreceptor cells: blue, green, and red. We have designed and chemically synthesized genes for each of these three pigments. The genes were expressed in COS cells, reconstituted with 11-cis-retinal chromophore, and purified to homogeneity using an immunoaffinity procedure. To facilitate the immunoaffinity purification, each pigment was modified at the carboxy terminus to contain an additional eight amino acid epitope for a monoclonal antibody previously used to purify bovine rhodopsin. The spectra for the isolated pigments had maxima of 424, 530, and 560 nm, respectively, for the blue, green, and red pigments. These maxima are in excellent agreement with the maxima previously observed by microspectrophotometry of individual human cone cells. The spectra are the first to be obtained from isolated human color vision pigments. They confirm the original identification of the three color vision genes, which was based on genetic evidence [Nathans, J., Thomas, D., & Hogness, D.S. (1986) Science 232, 193].