In enzymology, a retinol isomerase (EC 5.2.1.7) is an enzyme that catalyzes the chemical reaction Hence, this enzyme has one substrate, all-trans-retinol, and one product, 11-cis-retinol.
These enzymes are alternatively referred to as retinoid isomerases.
In vertebrates, RPE65 is the active retinol isomerase in the visual cycle.
A lack of RPE65 function results in congenital blindness in children (specifically Leber congenital amaurosis).
Emixustat, a partial inhibitor of RPE65, is currently in FDA clinical trials for the treatment of age-related macular degeneration.