title: Biosynthesis in vitro of Ii core glycosphingolipids from neolactotetraosylceramide by beta 1-3- and beta 1-6-N-acetylglucosaminyltransferases from mouse T-lymphoma.
abstract: The N-acetylglucosaminyltransferases probably involved in the biosynthesis in vitro of Ii core glycosphingolipids have been solubilized from a membrane preparation of mouse lymphoma P-1798 and partially characterized. The detergent-extracted membrane supernatant contains both beta 1-3- and beta 1-6-N-acetylglucosaminyltransferase activities that transfer [3H]GlcNAc from UDP-[3H]GlcNAc to the terminal galactose of neolactotetraosylceramide (Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc-ceramide; nLcOse4ceramide), to form the Ii core structures. The linkage of [3H]N-acetylglucosamine incorporated into the terminal galactose of nLcOse4Cer was determined from identification of 2,4,6-tri-O-methyl[3H]galactose and 2,3,4-tri-O-methyl[3H]galactose after hydrolysis of the permethylated enzymatic products, GlcNAc beta-[3H]Gal-GlcNAc-Gal-Glc-ceramide. In addition to the presence of beta-N-acetylglucosaminyltransferases, we have detected a galactosyltransferase activity in this soluble supernatant fraction that catalyzes the transfer of [14C]galactose from UDP-[14C]galactose to lactotriaosylceramide (GlcNAc beta 1-3Gal beta 1-4Glc-ceramide; LcOse3ceramide) to form nLcOse4ceramide, the acceptor in the N-acetylglucosaminyltransferase-catalyzed reaction.
mesh_terms: D000818:Animals; D002236:Carbohydrate Conformation; D002413:Cations, Divalent; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D005915:Globosides / Q000378:metabolism*; D005964:Glucosyltransferases / Q000378:metabolism*; D006028:Glycosphingolipids / Q000096:biosynthesis* / Q000378:metabolism*; D007700:Kinetics; D008223:Lymphoma / Q000201:enzymology*; D051379:Mice; D017351:N-Acetylglucosaminyltransferases
chemical_list: D002413:Cations, Divalent; D005915:Globosides; D006028:Glycosphingolipids; C036363:paragloboside; D005964:Glucosyltransferases; D017351:N-Acetylglucosaminyltransferases; C043132:glycosphingolipid beta1-3-N-acetylglucosaminyltransferase; C043131:glycosphingolipid beta1-6-N-acetylglucosaminyltransferase