Mnt2p and Mnt3p of Saccharomyces cerevisiae are members of the Mnn1p family of alpha-1,3-mannosyltransferases responsible for adding the terminal mannose residues of O-linked oligosaccharides

Glycobiology. 1999 Oct;9(10):1045-51. doi: 10.1093/glycob/9.10.1045.


The genome of Saccharomyces cerevisiae contains five genes that encode type II transmembrane proteins with significant amino acid similarity to the alpha-1,3-mannosyltransferase Mnn1p. The roles of the three genes most closely related to MNN1 were examined in mutants carrying single and multiple combinations of the disrupted genes. Paper chromatographic analysis of [2-3H]mannose-labeled O-linked oligosaccharides released by beta-elimination showed that the MNT2 (YGL257c) and MNT3 (YIL014w) genes in combination with MNN1 have overlapping roles in the addition of the fourth and fifth alpha-1,3-linked mannose residues to form Man4 and Man5 oligosaccharides whereas MNT4 (YNR059w) does not appear to be required for O-glycan synthesis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Genes, Fungal
  • Mannose / metabolism
  • Mannosyltransferases / genetics
  • Mannosyltransferases / metabolism*
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism*
  • Molecular Sequence Data
  • Multigene Family
  • Mutation
  • Oligosaccharides / biosynthesis
  • Oligosaccharides / chemistry
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins*
  • Sequence Homology, Amino Acid


  • Membrane Glycoproteins
  • Oligosaccharides
  • Saccharomyces cerevisiae Proteins
  • MNN1 protein, S cerevisiae
  • Mannosyltransferases
  • Mannose