Transfer of fatty acyl residues (FACYLs) from lecithin is the main way to esterify all-trans-retinol (atROL). Lecithin is a generic name for the yellowy-brown fatty substances in animals and tissues. It can be composed of phosphatidylcholines, phosphatidylethanolamines, and phosphatidylinositols. Fatty acyl transfer is catalyzed by Lecithin retinol acyltransferase (LRAT) and takes place near the endoplasmic reticulum membrane. The main fatty acyl moieties that are substrates for LRAT are palmitoyl, oleoyl, stearoyl and linoleoyl groups present in the A1 position of membrane phosphatidylcholine molecules. LRAT esterifies atROL with these acyl groups to form all-trans-retinyl esters (atREs). The aim is not storage but transport via chylomicrons (Ruiz et al. 1999).