Abstract

The chromophore of all known visual pigments consists of 11-cis-retinal (derived from either vitamin A1 or A2) or a hydroxylated derivative, bound to a protein (opsin) via a Schiff base. Absorption of a photon results in photoisomerization of the chromophore to all-trans-retinal and conversion of the visual pigment to the signaling form. Regeneration of the 11-cis-retinal occurs in an adjacent tissue and involves several enzymes, several water-soluble retinoid-binding proteins, and intra- and intercellular diffusional processes. Rod photoreceptor cells depend completely on the output of 11-cis-retinal from adjacent retinal pigment epithelial (RPE) cells. Cone photoreceptors cells can use 11-cis-retinal from the RPE and from a second more poorly characterized cycle, which appears to involve adjacent Müller (glial) cells. Recent progress in the characterization of rod and cone visual cycle components and reactions will result in the development of approaches to the amelioration of blinding eye diseases associated with visual cycle defects.

Links

Publisher Full Text

Authors

Saari JC

Institution

Department of Ophthalmology and Biochemistry, University of Washington, Seattle, WA 91895, USA. jsaari@u.washington.edu

Source

Annual review of nutrition 32: 2012 Aug 21 pg 125-45

MeSH

Animals
Humans
Retinal Cone Photoreceptor Cells
Retinal Pigment Epithelium
Retinal Pigments
Retinal Rod Photoreceptor Cells
Retinaldehyde
Vision, Ocular
Vitamin A

Pub Type(s)

Journal Article
Review

Language

eng

PubMed ID

22809103