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.
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.
Romero
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McGill Cancer Centre, McGill University, Montreal, Quebec, Canada.
Lussier
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Véronneau
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Sdicu
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AM
Herscovics
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A
Bussey
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H
D000595:Amino Acid Sequence; D005800:Genes, Fungal; D008358:Mannose / Q000378:metabolism; D008364:Mannosyltransferases / Q000235:genetics / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D005810:Multigene Family; D009154:Mutation; D009844:Oligosaccharides / Q000096:biosynthesis / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid
D008562:Membrane Glycoproteins; D009844:Oligosaccharides; D029701:Saccharomyces cerevisiae Proteins; C086604:MNN1 protein, S cerevisiae; D008364:Mannosyltransferases; D008358:Mannose