RPE65 is an enzyme of the visual cycle in the retinal pigment epithelium. It converts all-trans-retinyl esters into 11-cis-retinol, coupling a change of molecular geometry to processing of an ester substrate. The product participates in the pathway that replenishes the light-sensitive pigment system.[ref]
RPE65 is the isomerohydrolase in the retinoid visual cycle by Gennadiy Moiseyev and others. Abstract, substrate, product and catalytic role
A 1998 mouse experiment established a requirement for the protein: deficiency disrupted production of 11-cis vitamin-A derivatives and altered the visual response. Such a result identifies a necessary pathway component without by itself proving which reaction it catalyzes.[ref]
A 2005 study supplied more direct biochemical evidence. Expressing RPE65 in cultured cells produced the relevant activity when lecithin retinol acyltransferase was coexpressed to provide the substrate. Activity depended on the amount of expressed RPE65.[ref]
RPE65 is the isomerohydrolase in the retinoid visual cycle by Gennadiy Moiseyev and others. Abstract, recombinant expression and substrate-supplying partner
The comparison illustrates why an inactive preparation can reflect missing substrate supply as well as an absent or defective enzyme. New to topics? Read the docs here!