 Lecithin retinol acyltransferase

Lecithin retinol acyltransferase is an enzyme that transfers an acyl group from phosphatidylcholine, also called lecithin, to retinol, producing a retinyl ester. The donor's position and the acceptor's alcohol group are part of the reaction definition; describing it merely as an enzyme that binds vitamin A would omit its chemical function.^[ref]

This reaction supplies ester forms for retinoid storage and metabolism. It is distinct from changing retinyl-chain geometry, even though both operations occur in the broader visual cycle.^[ref]

A 2005 experiment illustrates why the distinction matters. Cultured cells expressing RPE65 required coexpression of lecithin retinol acyltransferase to provide the ester substrate for the measured production of 11-cis-retinol.^[ref] Missing product can therefore reflect a failure of upstream substrate supply rather than a failure of the downstream enzyme itself. Measuring both steps helps distinguish a pathway requirement from the identity of the catalyst performing a particular transformation.