Cloning and analysis of the Saccharomyces cerevisiae MNN9 and MNN1 genes required for complex glycosylation of secreted proteins

Proc Natl Acad Sci U S A. 1994 Mar 29;91(7):2723-7. doi: 10.1073/pnas.91.7.2723.


Proteins secreted by the yeast Saccharomyces cerevisiae are usually modified by the addition at asparagine-linked glycosylation sites of large heterogeneous mannan units that are highly immunogenic. Secreted proteins from mnn1 mnn9 mutant strains, in contrast, have homogeneous Man10GlcNAc2 oligosaccharides that lack the immunogenic alpha 1,3-mannose linkages. We have cloned and sequenced the MNN9 and MNN1 genes, both of which encode proteins with the characteristics of type II membrane proteins. Mnn9p is a membrane-associated protein with unknown function that is required for the addition of the long alpha 1,6-mannose backbone of the complex mannan, whereas Mnn1p is most likely the alpha 1,3-mannosyltransferase located in the Golgi apparatus.

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Carbohydrate Sequence
  • Cloning, Molecular
  • Endoplasmic Reticulum / chemistry
  • Fungal Proteins / metabolism*
  • Genes, Fungal / genetics*
  • Glycosylation
  • Golgi Apparatus / chemistry
  • Mannosyltransferases*
  • Membrane Glycoproteins / genetics*
  • Molecular Sequence Data
  • Protein Processing, Post-Translational*
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins*


  • Fungal Proteins
  • MNN9 protein, S cerevisiae
  • Membrane Glycoproteins
  • Saccharomyces cerevisiae Proteins
  • MNN1 protein, S cerevisiae
  • Mannosyltransferases

Associated data

  • GENBANK/L23752
  • GENBANK/L23753