title: Formation of 2-deoxyglucose-containing lipid-linked oligosaccharides. Interference with glycosylation of glycoproteins.
abstract: Crude membrane preparations from chick embryo cells catalyse the formation of dolichyl-di-N-acetylchitobiosyl diphosphate [Dol-PP-(GlcNAc)2] from uridine diphosphate N-acetylglucosamine (UDP-GlcNAc). The formation of this glycolipid was stimulated by exogenous dolichyl phosphate and inhibited by tunicamycin. Adding GDP-mannose to the cell-free system containing Dol-PP-(GlcNAc)2 by preincubation led to the formation of a lipid-linked oligosaccharide, containing 8--9 sugar residues. The formation of lipid-linked oligosaccharides was inhibited by GDP-2-deoxy-D-glucose (GDP-dGlc): in this case Dol-PP-(Glc-NAc)2-dGlc accumulated. Subsequent additions of mannosyl residues to this trisaccharide-lipid to form lipid-linked oligosaccharides were not possible. Concomitantly the glycosylation of proteins was blocked. Partially inhibitory conditions were obtained by adding both GDP-dGlc and GDP-Man with an excess of GDP-dGlc. Glycosylation of proteins was observed but the glycopeptides did not contain 2-deoxyglucosyl residues. Also in these cases 2-deoxyglucose-containing glycolipids accumulated. The main glycolipid formed under these conditions was Dol-PP-(GlcNAc)2-Man-dGlc. Lipid-linked oligosaccharides containing 2-deoxyglucose were formed under these conditions, although in small amounts, but were not transferred to protein. So the molecular basis of the inhibitory action of 2-deoxyglucose on glycosylation of protein is the incorporation of 2-deoxyglucosyl residues during early phases of the biosynthesis of the lipid-linked oligosaccharides.
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002642:Chick Embryo; D003837:Deoxy Sugars / Q000378:metabolism*; D003847:Deoxyglucose / Q000378:metabolism*; D004287:Dolichol Monophosphate Mannose / Q000378:metabolism; D004288:Dolichol Phosphates / Q000378:metabolism; D006017:Glycolipids / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism*; D009844:Oligosaccharides / Q000378:metabolism*; D014537:Uridine Diphosphate N-Acetylglucosamine / Q000378:metabolism
chemical_list: D003837:Deoxy Sugars; D004288:Dolichol Phosphates; D006017:Glycolipids; D006023:Glycoproteins; D009844:Oligosaccharides; D014537:Uridine Diphosphate N-Acetylglucosamine; D004287:Dolichol Monophosphate Mannose; D003847:Deoxyglucose