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Protein disulfide isomerase plays a key role in catalyzing the folding of secretory proteins. It features two catalytically inactive thioredoxin domains inserted between two catalytically active thioredoxin domains and an acidic C-terminal tail. The crystal structure of yeast PDI reveals that the four thioredoxin domains are arranged in the shape of a(More)
It has been proposed that cytoplasmic peptide:N-glycanase (PNGase) may be involved in the proteasome-dependent quality control machinery used to degrade newly synthesized glycoproteins that do not correctly fold in the ER. However, a lack of information about the structure of the enzyme has limited our ability to obtain insight into its precise biological(More)
During endoplasmic reticulum-associated degradation, the multifunctional AAA ATPase p97 is part of a protein degradation complex. p97 associates via its N-terminal domain with various cofactors to recruit ubiquitinated substrates. It also interacts with alternative substrate-processing cofactors, such as Ufd2, Ufd3, and peptide:N-glycanase (PNGase) in(More)
Protein disulfide isomerase (PDI) is believed to function in vivo by catalyzing the isomerization of disulfide bonds in proteins and thereby facilitating their folding. In S. cerevisiae PDI is encoded by an essential gene. Deletion of nearly one-third of the C-terminal residues of PDI altered PDI's cellular localization but not cell viability. Further(More)
To obtain information on the mechanism of glycosylation of ovalbumin, three types of experiments were performed with either hen oviduct membrane preparations or tissue slices and the antibiotic tunicamycin. First, experiments involving the addition of tunicamycin to oviduct membranes demonstrated that this antibiotic inhibited the synthesis of a(More)
Asparagine-linked glycosylation is the most ubiquitous protein co-translational modification in the endoplasmic reticulum (ER). 1 The enzyme that catalyzes this process is called oligosaccharyl transferase (OT). It catalyzes the transfer of an oligosaccharyl moiety (Glc 3 Man 9 GlcNAc 2) from the dolichol-linked pyrophosphate donor to the side chain of Asn(More)
Protein disulfide isomerase (PDI) interacts with secretory proteins, irrespective of their thiol content, late during translocation into the ER; thus, PDI may be part of the quality control machinery in the ER. We used yeast pdi1 mutants with deletions in the putative peptide binding region of the molecule to investigate its role in the recognition of(More)
In the yeast, Saccharomyces cerevisiae, oligosaccharyl transferase (OT) is composed of nine different transmembrane proteins. Using a glycosylatable peptide containing a photoprobe, we previously found that only one essential subunit, Ost1p, was specifically labeled by the photoprobe and recently have shown that it does not contain the recognition domain(More)
To study the fate of the yolk glycoproteins found in eggs and embryos of the sea urchin, Strongylocentrotus purpuratus, a polyclonal antibody to a 90-kDa polymannose glycoprotein found in the embryo was prepared. Immunoblot analysis of total proteins over the course of development showed that this antibody recognized a family of glycoproteins. Concomitant(More)