The yeast WBP1 is essential for oligosaccharyl transferase activity in vivo and in vitro.
Asparagine-linked N-glycosylation is a highly conserved and functionally important modification of proteins in eukaryotic cells. The central step in this process is a cotranslational transfer of lipid-linked core oligosaccharides to selected Asn-X-Ser/Thr-sequences of nascent polypeptide chains, catalysed by the enzyme N-oligosaccharyl transferase. In this report we show that the essential yeast protein WBP1 (te Heesen et al., 1991) is required for N-oligosaccharyl transferase in vivo and in vitro. Depletion of WBP1 correlates with a defect in transferring core oligosaccharides to carboxypeptidase Y and proteinase A in vivo. In addition, in vitro N-glycosylation of the acceptor peptide Tyr-Asn-Leu-Thr-Ser-Val using microsomal membranes from WBP1 depleted cells is reduced as compared with membranes from wild-type cells. We propose that WBP1 is an essential component of the oligosaccharyl transferase in yeast.
te Heesen
S
S
Institut für Molekularbiologie I, Universität Zürich, Hönggerberg, Switzerland.
Janetzky
B
B
Lehle
L
L
Aebi
M
M
D000483:Alleles; D000595:Amino Acid Sequence; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism; D001483:Base Sequence; D002268:Carboxypeptidases / Q000378:metabolism; D043402:Cathepsin A; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005696:Galactosidases / Q000235:genetics / Q000378:metabolism; D005800:Genes, Fungal; D006031:Glycosylation; D006602:Hexosyltransferases; D008565:Membrane Proteins; D008861:Microsomes / Q000201:enzymology; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D010957:Plasmids; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D013379:Substrate Specificity; D013696:Temperature; D014166:Transferases / Q000235:genetics / Q000378:metabolism*
D005656:Fungal Proteins; D008565:Membrane Proteins; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D014166:Transferases; D006602:Hexosyltransferases; C025620:dolichyl-diphosphooligosaccharide - protein glycotransferase; D005696:Galactosidases; D002268:Carboxypeptidases; D043402:Cathepsin A; C499283:PRC1 protein, S cerevisiae; C022633:serine carboxypeptidase; C022325:aspartic proteinase A; D016282:Aspartic Acid Endopeptidases