The ALG10 locus of Saccharomyces cerevisiae encodes the alpha-1,2 glucosyltransferase of the endoplasmic reticulum: the terminal glucose of the lipid-linked oligosaccharide is required for efficient N-linked glycosylation

Glycobiology. 1998 May;8(5):455-62. doi: 10.1093/glycob/8.5.455.


The biosynthesis of the lipid-linked oligosaccharide substrate for N-linked protein glycosylation follows a highly conserved pathway at the membrane of the endoplasmic reticulum. Based on the synthetic growth defect in combination with a reduced oligosaccharyltransferase activity (wbp1), we have identified alg10 mutant strains which accumulate lipid-linked Glc2Man9GlcNAc2. We cloned the corresponding wild-type gene and show in a novel in vitro assay that Alg10p is a dolichyl-phosphoglucose-dependent glucosyltransferase which adds the terminal alpha-1,2 glucose to the lipid-linked Glc2Man9GlcNAc2 oligosaccharide. Hypoglycosylation of secreted proteins in alg10 deletion strains demonstrates that the terminal alpha-1,2-linked glucose residue is a key element in substrate recognition by the oligosaccharyltransferase. This ensures that primarily completely assembled oligosaccharide is transferred to protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbohydrate Sequence
  • Endoplasmic Reticulum / enzymology
  • Glucosyltransferases / biosynthesis
  • Glucosyltransferases / genetics*
  • Glucosyltransferases / metabolism*
  • Glycosylation
  • Hexosyltransferases*
  • Intracellular Membranes / enzymology
  • Kinetics
  • Membrane Proteins*
  • Microsomes / enzymology*
  • Molecular Sequence Data
  • Oligosaccharides / biosynthesis*
  • Oligosaccharides / chemistry
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins*
  • Transferases / metabolism


  • Membrane Proteins
  • Oligosaccharides
  • Saccharomyces cerevisiae Proteins
  • Transferases
  • DIE2 protein, S cerevisiae
  • Glucosyltransferases
  • Hexosyltransferases
  • dolichyl-diphosphooligosaccharide - protein glycotransferase