| umls-concept:C0035331 | skos:definition | MSH: A carotenoid constituent of visual pigments. It is the oxidized form of retinol which functions as the active component of the visual cycle. It is bound to the protein opsin forming the complex rhodopsin. When stimulated by visible light, the retinal component of the rhodopsin complex undergoes isomerization at the 11-position of the double bond to the cis-form; this is reversed in "dark" reactions to return to the native trans-configuration.,CSP: biologically active form of vitamin A, which combines with certain proteins (opsins) to form visual pigments (e.g. rhodopsin); light absorption causes cis-trans isomerization of retinal, which is transduced by protein into neural signal and vision.,NCI: Retinoid with an aldehyde group.,CHV: chemical substance in the eye that helps to see | lld:umls |
