| Structural highlights
Disease
[STT3A_HUMAN] STT3A-CDG. The disease is caused by mutations affecting the gene represented in this entry. [RPN1_HUMAN] Acute myeloid leukemia with inv(3)(q21q26.2) or t(3;3)(q21;q26.2).
Function
[RPN2_HUMAN] 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.[UniProtKB:F1PCT7] [TM258_HUMAN] 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 (PubMed:26472760, PubMed:27974209). Involved in ER homeostasis in the colonic epithelium (By similarity).[UniProtKB:P61166][1] [2] [A0A024RAD5_HUMAN] 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).[RuleBase:RU361142] [OST4_HUMAN] May be involved in N-glycosylation through its association with N-oligosaccharyl transferase (By similarity). [OSTC_HUMAN] 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. May be involved in N-glycosylation of APP (amyloid-beta precursor protein). Can modulate gamma-secretase cleavage of APP by enhancing endoprotelysis of PSEN1.[3] [STT3A_HUMAN] 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 (By similarity). 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 (PubMed:19167329).[UniProtKB:P39007][4] [DAD1_HUMAN] 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 (PubMed:22467853). 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 (By similarity). Required for the assembly of both SST3A- and SS3B-containing OST complexes. Loss of the DAD1 protein triggers apoptosis (PubMed:22467853).[UniProtKB:E2R4X3][5] [RPN1_HUMAN] 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.[UniProtKB:E2RQ08]
Publication Abstract from PubMed
Oligosaccharyltransferase (OST) catalyzes the transfer of a high-mannose glycan onto secretory proteins in the endoplasmic reticulum. Mammals express two distinct OST complexes that act in a cotranslational (OST-A) or posttranslocational (OST-B) manner. Here, we present high-resolution cryo-electron microscopy structures of human OST-A and OST-B. Although they have similar overall architectures, structural differences in the catalytic subunits STT3A and STT3B facilitate contacts to distinct OST subunits, DC2 in OST-A and MAGT1 in OST-B. In OST-A, interactions with TMEM258 and STT3A allow ribophorin-I to form a four-helix bundle that can bind to a translating ribosome, whereas the equivalent region is disordered in OST-B. We observed an acceptor peptide and dolichylphosphate bound to STT3B, but only dolichylphosphate in STT3A, suggesting distinct affinities of the two OST complexes for protein substrates.
Cryo-electron microscopy structures of human oligosaccharyltransferase complexes OST-A and OST-B.,Ramirez AS, Kowal J, Locher KP Science. 2019 Dec 13;366(6471):1372-1375. doi: 10.1126/science.aaz3505. PMID:31831667[6]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Blomen VA, Majek P, Jae LT, Bigenzahn JW, Nieuwenhuis J, Staring J, Sacco R, van Diemen FR, Olk N, Stukalov A, Marceau C, Janssen H, Carette JE, Bennett KL, Colinge J, Superti-Furga G, Brummelkamp TR. Gene essentiality and synthetic lethality in haploid human cells. Science. 2015 Nov 27;350(6264):1092-6. doi: 10.1126/science.aac7557. Epub 2015, Oct 15. PMID:26472760 doi:http://dx.doi.org/10.1126/science.aac7557
- ↑ Graham DB, Lefkovith A, Deelen P, de Klein N, Varma M, Boroughs A, Desch AN, Ng ACY, Guzman G, Schenone M, Petersen CP, Bhan AK, Rivas MA, Daly MJ, Carr SA, Wijmenga C, Xavier RJ. TMEM258 Is a Component of the Oligosaccharyltransferase Complex Controlling ER Stress and Intestinal Inflammation. Cell Rep. 2016 Dec 13;17(11):2955-2965. doi: 10.1016/j.celrep.2016.11.042. PMID:27974209 doi:http://dx.doi.org/10.1016/j.celrep.2016.11.042
- ↑ Wilson CM, Magnaudeix A, Yardin C, Terro F. DC2 and keratinocyte-associated protein 2 (KCP2), subunits of the oligosaccharyltransferase complex, are regulators of the gamma-secretase-directed processing of amyloid precursor protein (APP). J Biol Chem. 2011 Sep 9;286(36):31080-91. doi: 10.1074/jbc.M111.249748. Epub 2011, Jul 18. PMID:21768116 doi:http://dx.doi.org/10.1074/jbc.M111.249748
- ↑ Ruiz-Canada C, Kelleher DJ, Gilmore R. Cotranslational and posttranslational N-glycosylation of polypeptides by distinct mammalian OST isoforms. Cell. 2009 Jan 23;136(2):272-83. doi: 10.1016/j.cell.2008.11.047. PMID:19167329 doi:10.1016/j.cell.2008.11.047
- ↑ Roboti P, High S. The oligosaccharyltransferase subunits OST48, DAD1 and KCP2 function as ubiquitous and selective modulators of mammalian N-glycosylation. J Cell Sci. 2012 Jul 15;125(Pt 14):3474-84. doi: 10.1242/jcs.103952. Epub 2012, Mar 30. PMID:22467853 doi:http://dx.doi.org/10.1242/jcs.103952
- ↑ Ramirez AS, Kowal J, Locher KP. Cryo-electron microscopy structures of human oligosaccharyltransferase complexes OST-A and OST-B. Science. 2019 Dec 13;366(6471):1372-1375. doi: 10.1126/science.aaz3505. PMID:31831667 doi:http://dx.doi.org/10.1126/science.aaz3505
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