COENZYME A-INDEPENDENT MONOACYLGLYCEROL ACYLTRANSFERASE FROM RAT INTESTINAL-MUCOSA

Rat intestinal mucosa contains high diacylglycerol-synthesizing activi ty (monoacylglycerol acyltransferase (MGAT) activity) due to monoacylg lycerol and fatty acid, independently of coenzyme A and ATP. MGAT acti vity was purified from rat intestinal mucosa by successive chromatogra phy separations on DEAE-cellulose, CM- Sephadex, and anti-IgG-Sepharos e against rat pancreatic lipase. The enzyme was electrophoretically ho mogeneous, and its molecular weight was 49,000, which is identical wit h that of rat pancreatic lipase. Immunoblotting analysis with antibody against rat pancreatic lipase showed one immunoreactive protein with an estimated molecular weight of 49,000. The activity of the purified enzyme was completely inhibited by addition of the antibody. Using imm unocytochemical techniques, it was found that immunoreactive protein a gainst rat pancreatic lipase was uniformly distributed within the abso rptive cells of the intestine but was absent from the microvillar memb rane. The MGAT activity of intestinal mucosal homogenate was inhibited by about 65% by addition of antibody against rat pancreatic lipase. T rioleoylglycerol- and dioleoylglycerol-hydrolyzing activities of the p urified enzyme and pancreatic lipase were inhibited by addition of int estinal mucosa extract. These results suggest that pancreatic lipase i s present in intestinal absorptive cells and that it may contribute to resynthesis of diacylglycerol from monoacylglycerol and fatty acids i n these cells.