Isolation of glucose-containing high-mannose glycoprotein core oligosaccharides.
The total cell wall mannoprotein has been isolated from a mutant of Saccharomyces cerevisiae that fails to remove the glucose units of the dolichol-linked precursor after transfer of the oligosaccharide to asparagine units in the protein. The oligosaccharides released from this mannoprotein by endoglucosaminidase H digestion show 1H NMR signals assignable to three alpha-linked glucose units as delta 5.52, 5.27, and 5.17, and a comparison with the chemical shifts of reference compounds shows that these signals are consistent with the structure alpha Glc----2 alpha Glc----3 alpha Man----2. This provides a direct confirmation for the structure previously assigned to the lipid-linked precursor. Analysis of the larger oligosaccharides confirms that the presence of the glucose units does not prevent elongation of the alpha 1----6-linked polymannose backbone or addition of alpha 1----3-linked mannose to the core.
D005947:Glucose / Q000032:analysis; D006023:Glycoproteins / Q000032:analysis* / Q000378:metabolism; D008562:Membrane Glycoproteins; D008968:Molecular Conformation; D009154:Mutation; D009844:Oligosaccharides / Q000302:isolation & purification*; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D012441:Saccharomyces cerevisiae / Q000378:metabolism
D006023:Glycoproteins; D008562:Membrane Glycoproteins; D009844:Oligosaccharides; D011498:Protein Precursors; C025363:mannoproteins; D005947:Glucose