11cisretinals

11cisretinals refers to a group of retinal molecules that possess a cis configuration at the 11th carbon double bond of the vitamin A aldehyde backbone. The most commonly studied member of this group is 11-cis‑retinal, a chromophore that plays a critical role in vertebrate vision. In the retina, 11-cis‑retinal is covalently attached to opsin proteins, forming visual pigments such as rhodopsin in rod cells and cone opsins in cone cells. When a photon of light is absorbed by the chromophore, the 11‑cis double bond isomerizes to the all‑trans configuration, triggering the activation of the associated G‑protein‑coupled receptor and initiating the visual signal transduction cascade.

The biosynthesis of 11-cis‑retinals involves a retinoid cycle in which all‑trans‑retinol is re‑isomerized to 11‑cis‑retinol by the retinal pigment epithelium, followed by oxidation to 11‑cis‑retinal. Enzymes such as RPE65 catalyze the isomerization of all‑trans‑retinyl esters to 11-cis‑retinyl esters, which are then hydrolyzed to release 11-cis‑retinal for incorporation into visual pigments. Deficiencies in enzymes involved in this cycle can lead to retinal diseases, including retinitis pigmentosa and Leber congenital amaurosis.

Beyond vision, 11‑cis‑retinals are involved in regulating gene expression and cellular differentiation when oxidized to retinoic acid, although this process primarily involves 11‑cis‑retinoic acid rather than the aldehyde form. The study of 11‑cis‑retinals remains essential for understanding both normal visual function and the molecular basis of retinal disorders.