Cl. Yip et al., CLONING AND ANALYSIS OF THE SACCHAROMYCES-CEREVISIAE MNN9 AND MNN1 GENES REQUIRED FOR COMPLEX GLYCOSYLATION OF SECRETED PROTEINS, Proceedings of the National Academy of Sciences of the United Statesof America, 91(7), 1994, pp. 2723-2727
Proteins secreted by the yeast Saccharomyces cerevisiae are usually mo
dified by the addition at asparagine-linked glycosylation sites of lar
ge heterogeneous mannan units that are highly immunogenic. Secreted pr
oteins from mnn1 mnn9 mutant strains, in contrast, have homogeneous Ma
n10GlcNAC2 oligosaccharides that lack the immunogenic alpha1,3-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 backb
one of the complex mannan, whereas Mnn1p is most likely the alpha1,3-m
annosyltransferase located in the Golgi apparatus.