Triacylglycerol synthesis by purified triacylglycerol synthetase of rat intestinal mucosa. Role of acyl-CoA acyltransferase.
The activities of the proposed triacylglycerol synthetase complex, acyl-CoA ligase, acyl-CoA acyltransferase (AAT), monoacylglycerol acyltransferase (MGAT), and diacylglycerol acyltransferase (DGAT), coeluted upon Cibacron blue 3GA-agarose affinity chromatography of detergent-solubilized rat intestinal microsomes. The AAT activity is associated with a 54-kDa protein, that binds covalently an acyl group from acyl-CoA via a thiol ester linkage (Lehner, R. and Kuksis, A. (1993) J. Biol. Chem. 268, 24726-24733). Reagents that prevent the acyl-AAT formation inhibit triacylglycerol synthesis as does the removal of AAT from the complex by immunoprecipitation. In the absence of mono- and diacylglycerol acceptors, the acyl group is transferred to water. It is proposed that triacylglycerol synthesis proceeds via a sequential transfer of acyl groups from acyl-CoA ligase to the AAT, from which they are passed to the mono- and diacylglycerol acyltransferases for incorporation into the di- and triacylglycerols depending on the availability of the acyl acceptors.
Lehner
R
R
Banting and Best Department of Medical Research, C. H. Best Institute, Toronto, Ontario, Canada.
Kuksis
A
A
D000214:Acyl Coenzyme A / Q000378:metabolism*; D000217:Acyltransferases / Q000302:isolation & purification / Q000494:pharmacology*; D000818:Animals; D051048:Diacylglycerol O-Acyltransferase; D007413:Intestinal Mucosa / Q000201:enzymology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013438:Sulfhydryl Compounds / Q000378:metabolism; D014280:Triglycerides / Q000096:biosynthesis*
D000214:Acyl Coenzyme A; D013438:Sulfhydryl Compounds; D014280:Triglycerides; D000217:Acyltransferases; D051048:Diacylglycerol O-Acyltransferase