2lgz
From Proteopedia
Solution structure of STT3P
Structural highlights
FunctionSTT3_YEAST Catalytic subunit of the N-oligosaccharyl transferase (OST) complex which catalyzes the transfer of a high mannose oligosaccharide to an asparagine residue within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains. N-glycosylation occurs cotranslationally and the complex associates with the Sec61 complex at the channel-forming translocon complex that mediates protein translocation across the endoplasmic reticulum (ER). All subunits are required for a maximal enzyme activity.[1] Publication Abstract from PubMedN-Glycosylation is an essential and highly conserved protein modification. In eukaryotes, it is catalyzed by a multisubunit membrane-associated enzyme, oligosaccharyltransferase (OT). We report the high resolution structure of the C-terminal domain of eukaryotic Stt3p. Unlike its soluble beta-sheet-rich prokaryotic counterparts, our model reveals that the C-terminal domain of yeast Stt3p is highly helical and has an overall oblate spheroid-shaped structure containing a membrane-embedded region. Anchoring of this protein segment to the endoplasmic reticulum membrane is likely to bring the membrane-embedded donor substrate closer, thus facilitating glycosylation efficiency. Structural comparison of the region near the WWDYG signature motif revealed that the acceptor substrate-binding site of yeast OT strikingly resembles its prokaryotic counterparts, suggesting a conserved mechanism of N-glycosylation from prokaryotes to eukaryotes. Furthermore, comparison of the NMR and cryo-EM structures of yeast OT revealed that the molecular architecture of this acceptor substrate-recognizing domain has interesting spatial specificity for interactions with other essential OT subunits. Eukaryotic N-Glycosylation Occurs via the Membrane-anchored C-terminal Domain of the Stt3p Subunit of Oligosaccharyltransferase.,Huang C, Bhaskaran R, Mohanty S J Biol Chem. 2012 Sep 21;287(39):32450-8. Epub 2012 Aug 3. PMID:22865878[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. Loading citation details.. Citations No citations found See AlsoReferences
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