Characterization of a glucosyltransferase activity in liver plasma membrane: modulation by cations and lipidic effectors.
1. Glucosyltransferase activity incorporating [14C]glucose from UDP-[14C]glucose onto endogenous lipidic acceptors was localized primarily in the plasma membrane of liver. 2. Incubation of plasma membrane by phosphatidyl-choline liposomes loaded with dolichyl-phosphate stimulated the enzymatic activity. 3. This enzyme required Mg2+ for maximal catalitic activity. Ca2+ could substitute Mg2+. 4. Mn2+ acted as a partial non-competitive inhibitor of the Mg2+-activated glucosyltransferase. 5. This enzyme can be modulated by neutral and acidic phospholipids; the most efficient were phosphatidyl-serine and phosphatidyl-inositol. 6. The enzymatic activity was not significantly changed by cholesterol alone but it is greatly enhanced by liposomes loaded with dolichyl-phosphate and cholesterol.
Fernández-Briera
A
A
Department of Biochemistry and Molecular Biology, University of Leon, Spain.
Louisot
P
P
Morelis
R
R
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002413:Cations, Divalent / Q000494:pharmacology*; D002462:Cell Membrane / Q000201:enzymology; D005947:Glucose / Q000378:metabolism; D005964:Glucosyltransferases / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D008623:Mercaptoethanol / Q000494:pharmacology; D051379:Mice; D012969:Sodium Fluoride / Q000494:pharmacology
D002413:Cations, Divalent; D008345:Manganese; D008623:Mercaptoethanol; D012969:Sodium Fluoride; D005964:Glucosyltransferases; D008274:Magnesium; D005947:Glucose; D002118:Calcium