The visual cycle of the cone photoreceptors of the retina.
The photoreceptors of the eye's retina consist of rods and cones; rods serve vision in dim light, whereas cones serve high-resolution color vision in daylight. The first event in vision is the light-initiated isomerization of 11-cis-retinal, which is attached to rod or cone opsin, to all-trans-retinal. The regeneration of 11-cis-retinal comprises the well-known visual cycle in rods. By using cone-dominant retinas from chickens and ground squirrels, a visual cycle has been discovered in cones that differs radically from that in rods, mainly in the mechanism of isomerization of all-trans-retinol to 11-cis-retinol, and the latter's oxidation to 11-cis-retinal.
Wolf
George
G
Department of Nutritional Sciences and Toxicology, University of California, Berkeley, CA 94720-3104, USA.
D000818:Animals; D002645:Chickens; D006801:Humans; D012160:Retina; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology / Q000378:metabolism*; D012168:Retinal Pigments / Q000737:chemistry / Q000378:metabolism*; D017948:Retinal Rod Photoreceptor Cells / Q000166:cytology / Q000378:metabolism*; D012172:Retinaldehyde / Q000737:chemistry; D017299:Rod Opsins; D012589:Sciuridae; D013237:Stereoisomerism; D014785:Vision, Ocular / Q000502:physiology*; D014801:Vitamin A / Q000737:chemistry
D012168:Retinal Pigments; D017299:Rod Opsins; D014801:Vitamin A; D012172:Retinaldehyde