Cyanopsin

Title: Cyanopsin
Literature References: Photoreceptor protein found in the retinal cone cells of fresh water and migratory fish, lampreys, and certain amphibians; corresponds to the rod pigment, porphyropsin, q.v. Absorption maximum ~620 nm. Composed of the chromophore 11-cis-3-dehydroretinal, q.v., bound to a photopsin, the specific protein component of cone cells (see Opsins). Proposed existence as a visual pigment and in vitro synthesis from 3-dehydroretinal and chicken photopsin: G. Wald, Science 118, 505 (1953). Demonstration of natural occurrence by microspectrophotometry: P. Liebman, G. Entine, Nature 216, 501 (1967). Methods for prepn and assay: R. Hubbard et al., Methods Enzymol. 18, 615-653 (1971). Photochemistry and biological activity: G. Wald, Science 162, 230 (1968). A trichromatic cone system utilizing 3-dehydroretinal as chromophore has been noted to occur in certain amphibians and fish. Three photochemically distinct pigments, corresponding to those of retinal-based color vision, have been identified: P. A. Liebman in Handbook of Sensory Physiology Vol. VII(1), H. J. A. Dartnall, Ed. (Springer-Verlag, New York, 1972) pp 481-528. A visual system is generally based on one type of chromophore combined with various opsins. However, pigments utilizing both types of chromophore have been found to co-exist in the retina of some of these species. Demonstration of paired-pigment cone systems: E. R. Loew, H. J. A. Dartnall, Vision Res. 11, 551 (1976); A. T. C. Tsin et al., ibid. 21, 943 (1981). Absorption spectrum: J. E. M. Mooij, T. J. T. P. van den Berg, ibid. 23 (1983).
Cyanuric Acid Cyanuric Chloride Cyazofamid Cycasin Cyclacillin

Normalised absorption spectra of the three human photopsins and of human rhodopsin (dashed).

Iodopsins (also known as Cone opsins) are the photoreceptor proteins found in the cone cells of the retina that are the basis of color vision. Iodopsins are very close analogs of the visual purple rhodopsin that is used in night vision. Iodopsins consist of a protein called photopsin and a bound chromophore, retinal.