Membrane-bounded lipid particles from beef heart acylglycerol synthesis.

The site for the synthesis of triacylglycerol in heart muscle has been the subject of this study. Acyl-CoA synthetase and glycerophosphate acyltransferase, enzymest necessary for the synthesis of triacylglycerol, have been found to be associated to membrane-bounded lipid particles. The acylglycerol synthesizing enzymes exhibit higher activities in the membrane-bounded lipid particles than in the mitochondrial or microsomal fractions. Futhermore, the lipid particles have the greater capacity for synthesis of diacylglycerols and triacylglycerols, whereas monoacylgly cerols are the major neutral lipid product in both the mitochondrial and the microsomal fractions. The results indicate that the membrane-bounded lipid particle may be the site for the synthesis as well as for the storage of intracellular triacylglycerol of the heart.