Glycoprotein biosynthesis in plants. Demonstration of lipid-linked oligosaccharides of mannose and N-acetylglucosamine.
Previous studies from this laboratory have shown that particulate preparations from maturing cotton fibers catalyze the transfer of mannose from GDP-[14C]mannose into mannosylphosphorylpolyisoprenol (Forsee, W. T., and Elbein,A. D. (1973) J. Biol. Chem. 248, 2858-2867). In this report, we show that these particulate preparations also catalyze the inocoporation of mannose from GDP-[14C]mannose into lipid-linked oligosaccharides and into glycoprotein. The oligosaccharide-lipids were treated with dilute acid to liberate the water-soluble oligosaccharides and these oligosaccharides could then be separated into seven or eight distinct radioactive peaks by paper chromatography in isobutyric acid/NH4OH/H2betaO (57/4/39). The smallest of the oligosaccharides appears to be a trisaccharide with the structure Man leads to GlcNAc-GlcNAc. Thus the oligosaccharides attached to the lipids apparently range in size from those having 3 glycose units to those having approximately 8 to 10 glycose units. The radioactivity in the smaller-sized oligosaccharide-lipids could be chased into the larger oligosaccharide-lipids by a second incubation in the presence of unlabeled GDP-mannose. The sugar at the reducing ends of the oligosaccharides was identified as GlcNAc while some mannose (20 to 30%) was present in alpha linkages at the nonreducing ends...
D000117:Acetylglucosamine / Q000378:metabolism; D004229:Dithiothreitol / Q000494:pharmacology; D005944:Glucosamine / Q000031:analogs & derivatives*; D006023:Glycoproteins / Q000096:biosynthesis*; D003368:Gossypium / Q000187:drug effects / Q000378:metabolism; D006902:Hydroxymercuribenzoates / Q000494:pharmacology; D007700:Kinetics; D008070:Lipopolysaccharides / Q000378:metabolism*; D008358:Mannose / Q000378:metabolism*; D009844:Oligosaccharides / Q000032:analysis / Q000096:biosynthesis*; D010944:Plants / Q000187:drug effects / Q000378:metabolism*
D006023:Glycoproteins; D006902:Hydroxymercuribenzoates; D008070:Lipopolysaccharides; D009844:Oligosaccharides; D005944:Glucosamine; D008358:Mannose; D004229:Dithiothreitol; D000117:Acetylglucosamine