PALMITOYL-COA SYNTHETASE ON THE EXTERNAL SURFACE OF ISOLATED RAT HEPATOCYTES

After incubating isolated rat hepatocytes with [1-C-14]palmitic acid, CoA and ATP (+MgCl2), a significant amount of [1-C-14]palmitoyl-CoA wa s found in the incubation medium. There was no correlation between its rate of synthesis and the degree of intactness of the cells. The resu lts indicate that there is a long-chain fatty acyl-CoA synthetase acti ve on the external surface of the hepatocyte plasma membrane. The acti vity of this enzyme was negligible in primary cultures of rat hepatocy tes, suggesting that the exofacial long-chain acyl-CoA synthetase is a n artifact of the collagenase perfusion technique used to prepare the hepatocytes.