Evidence for a lecithin-retinol acyltransferase activity in the rat small intestine.

摘要: Cellular retinol-binding protein, type II (CRBP (II] is an abundant protein of the mature enterocytes small intestine. It has been shown to direct retinol acyl-CoA-independent esterifying activity that utilizes endogenous acyl donor (Ong, D.E., Kakkad, B., and MacDonald, P.N. (1987) J. Biol. Chem. 262, 2729-2736). Here we report this in intestinal microsomes will catalyze transfer moieties from exogenous phosphatidylcholine (PC) retinol-CRBP(II) produce retinyl esters. The microsomal displayed positional selectivity as only sn-1-acyl moiety PC was transferred retinol-CRBP(II). ester synthase selective for substrates phosphatidylethanolamine, phosphatidic acid, or free fatty acid not observed. Some formation esters observed with acyl-CoA, but amount produced considerably lower than could be due a different enzyme activity. Inhibitor studies clearly distinguished between activities responsible acyl-CoA-dependent esterification phosphatidylcholine-dependent retinol. results provide strong evidence intestine proceeds via transacylase mechanism similar established cholesterol by lecithin-cholesterol acyltransferase.