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ITM1
Catalytic subunit of the oligosaccharyl transferase (OST) complex that catalyzes the initial transfer of a defined glycan (Glc(3)Man(9)GlcNAc(2) in eukaryotes) from the lipid carrier dolichol-pyrophosphate to an asparagine residue within an Asn-X-Ser/Thr consensus motif in nascent polypeptide chains, the first step in protein N-glycosylation. 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. This subunit contains the active site and the acceptor peptide and donor lipid-linked oligosaccharide (LLO) binding pockets. STT3A is present in the majority of OST complexes and mediates cotranslational N-glycosylation of most sites on target proteins, while STT3B-containing complexes are required for efficient post-translational glycosylation and mediate glycosylation of sites that have been skipped by STT3A. Belongs to the STT3 family. Expressed at high levels in placenta, liver, muscle and pancreas, and at very low levels in brain, lung and kidney. Expressed in skin fibroblasts (at protein level). 2 alternatively spliced human isoforms have been reported. Note: This description may include information from UniProtKB.
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| Protein type: EC 2.4.99.18; Endoplasmic reticulum; Membrane protein, integral; Membrane protein, multi-pass; Transferase |
| Chromosomal Location of mouse Ortholog: 9 A4|9 20.67 cM |
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Cellular Component:
endoplasmic reticulum; endoplasmic reticulum membrane; membrane; oligosaccharyltransferase complex
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Molecular Function:
dolichyl-diphosphooligosaccharide-protein glycotransferase activity; glycosyltransferase activity; metal ion binding; oligosaccharyl transferase activity; transferase activity
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Biological Process:
co-translational protein modification; post-translational protein modification; protein glycosylation; protein N-linked glycosylation; protein N-linked glycosylation via asparagine
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Reference #:
P46978
(UniProtKB)
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Alt. Names/Synonyms: AA408947; B5; BB081708; Dolichyl-diphosphooligosaccharide--protein glycosyltransferase subunit STT3A; Integral membrane protein 1; intergral membrane protein 1; Itm; Itm1; Oligosaccharyl transferase subunit STT3A; STT3, subunit of the oligosaccharyltransferase complex, homolog A (S. cerevisiae); STT3-A; Stt3a
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Gene Symbols: Stt3a
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Molecular weight:
80,598 Da
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Basal Isoelectric point:
8.3
Predict pI for various phosphorylation states
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