Mapping the interaction of the STT3 subunit of the oligosaccharyl transferase complex with nascent polypeptide chains

UMMS Affiliation

Department of Biochemistry and Molecular Pharmacology, Department of Neurobiology University of Massachusetts Medical School



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Medical Subject Headings

Animals; Binding Sites; Cattle; Cross-Linking Reagents; Glycosylation; Hexosyltransferases; Light; Membrane Proteins; Mutagenesis, Site-Directed; Peptides; Polysaccharides; Prolactin; Protein Precursors; RNA, Messenger; Saccharomyces cerevisiae Proteins; Structure-Activity Relationship


Many secretory and membrane proteins are N-glycosylated by the oligosaccharyl transferase complex during their translocation across the endoplasmic reticulum membrane. Several experimental observations suggest that the highly conserved STT3 subunit contains the active site of the oligosaccharyl transferase. Here, we report a detailed study of the interaction between the active site of the STT3 protein and nascent polypeptide chains using an in vitro photocrosslinking technique. Our results show that the addition of a glycan moiety in a stretch of approximately 15 residues surrounding a QK(*)T cross-linking site impairs the interaction between the nascent chain and STT3.

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Citation: J Biol Chem. 2005 Dec 9;280(49):40489-93. Epub 2005 Oct 10. Link to article on publisher's site

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