Abstract
Anp1p, Van1p and Mnn9p constitute a family of membrane proteins required for proper Golgi function in Saccharomyces cerevisiae. We demonstrate that these proteins colocalize within the cis Golgi, and that they are physically associated in two distinct complexes, both of which contain Mnn9p. Furthermore, we identify two new proteins in the Anp1p-Mnn9p-containing complex which have homology to known glycosyltransferases. Both protein complexes have alpha-1, 6-mannosyltransferase activity, forming a series of poly-mannose structures. These reaction products also contain some alpha-1, 2-linked mannose residues. Our data suggest that these two multi-protein complexes are responsible for the synthesis and initial branching of the long alpha-1,6-linked backbone of the hypermannose structure attached to many yeast glycoproteins.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Enzyme Activation
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Fungal Proteins / metabolism
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GATA Transcription Factors
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Glycosyltransferases / chemistry
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Golgi Apparatus / enzymology*
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Golgi Apparatus / metabolism
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Macromolecular Substances
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Mannose / metabolism
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Mannosyltransferases / metabolism*
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Membrane Glycoproteins / chemistry
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Membrane Glycoproteins / metabolism
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Membrane Proteins / chemistry
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Molecular Sequence Data
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Saccharomyces cerevisiae / enzymology*
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Saccharomyces cerevisiae / metabolism
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Saccharomyces cerevisiae Proteins*
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Transcription Factors / chemistry
Substances
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Fungal Proteins
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GATA Transcription Factors
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GZF3 protein, S cerevisiae
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MNN9 protein, S cerevisiae
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Macromolecular Substances
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Membrane Glycoproteins
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Membrane Proteins
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Saccharomyces cerevisiae Proteins
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Transcription Factors
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VAN1 protein, S cerevisiae
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Glycosyltransferases
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HOC1 protein
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ANP1 protein, S cerevisiae
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Mannosyltransferases
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alpha 1,6-mannosyltransferase
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Mannose