CHARACTERIZATION OF A MANNOSYL-LIPID COMPOUND OF MICROSOMAL FRACTIONS OF RAT PANCREAS AND INFLUENCE OF DIET

High-starch diet induces an activation of rat pancreatic microsomal mannosyl-transferase activity as compared with a standard diet or a high-fat diet. This increase is found in a mannose-containing lipid which is identified as a dolichyl-phosphoryl-mannose on the criteria of DEAE-cellulose chromatography, alkaline and acid hydrolysis, TLC and identity of this endogenous product with the [14C]mannose-containing product synthesized in the presence of exogenous dolichyl-monophosphate added to the incubation medium. Kinetic parameters (Km and Vmax) of the enzyme vs. polyprenic acceptor are not modified by the diet. The activation of the mannose transfer may be principally due to an increase of the polyprenic endogenous acceptor by the high-starch diet.