The visual cycle operates via an isomerase acting on all-trans retinol in the pigment epithelium

摘要: Thirty years have elapsed since Wald and his colleagues showed that 11-cis retinal was isomerized to all-trans when rhodopsin bleached, yet little has been understood about the reverse process generates for regeneration. It is not known whether isomerization enzyme-mediated, it occurs in pigment epithelium or retina, retinal, retinol, a retinyl ester vitamin A compound isomerized. Radiolabeled retinol high-performance liquid chromatography now used demonstrate existence of an eye-specific, membrane-bound enzyme (retinol isomerase) converts dark. Retinol isomerase concentrated epithelium; this localization clarifies role tissue regeneration explains need transfer from rod outer segments during visual cycle.