STT3A

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0004579 dolichyl-diphosphooligosaccharide-protein glycotransferase activity	IBA GO_REF:0000033	ACCEPT	Summary: Core molecular function of STT3A as the catalytic subunit of the OST complex. This phylogenetic (IBA) call agrees with direct experimental evidence for human STT3A (IDA/IMP: PMID:19167329, PMID:31296534, PMID:38670073, PMID:39509507) and with the UniProt EC 2.4.99.18 catalytic-activity assignment. Correct and central.
GO:0006487 protein N-linked glycosylation	IBA GO_REF:0000033	ACCEPT	Summary: Core biological process. STT3A carries out the initial glycan-transfer step of protein N-linked glycosylation. Well supported by experimental annotations to the same term (PMID:19167329, PMID:31296534, PMID:38670073) and by the UniProt PATHWAY (protein glycosylation). Correct and central.
GO:0008250 oligosaccharyltransferase complex	IBA GO_REF:0000033	KEEP AS NON CORE	Summary: STT3A is a component of the OST complex. This is correct at the generic-complex level; the more precise term for the STT3A-containing complex is GO:0160226 (oligosaccharyltransferase complex A), annotated by IDA elsewhere in this record. Retained as accurate but generic.
GO:0043687 post-translational protein modification	IBA GO_REF:0000033	MARK AS OVER ANNOTATED	Summary: STT3A is specifically the CO-translational OST catalytic subunit; it acts on nascent chains as they enter the ER lumen, whereas post-translocational/post-translational glycosylation is the specialty of the paralog STT3B. This generic family-level IBA term does not capture STT3A's core biology and better fits STT3B. Not removed (a family-level inference is not strictly wrong), but flagged as an over-annotation for STT3A. Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH WRONG ORTHOLOG OR PARALOG Sources checked: PANTHER:PTN000356208 · STT3 family node (GO_Central IBA) SUPPORTS SOURCE BUT NOT TARGET UniProtKB:Q8TCJ2 · STT3B (human) SUPPORTS SOURCE BUT NOT TARGET
GO:0004576 oligosaccharyl transferase activity	IEA GO_REF:0000002	MODIFY	Summary: InterPro-based (IPR003674) electronic assignment of a generic oligosaccharyl transferase activity. This is a less-informative parent of the precise catalytic function GO:0004579 (dolichyl-diphosphooligosaccharide-protein glycotransferase activity), which is directly supported by experimental evidence for STT3A. Replace with the specific term. Proposed replacements: dolichyl-diphosphooligosaccharide-protein glycotransferase activity
GO:0004579 dolichyl-diphosphooligosaccharide-protein glycotransferase activity	IEA GO_REF:0000120	ACCEPT	Summary: Electronic assignment of the core catalytic activity from the RHEA:22980 / EC 2.4.99.18 mapping. This is STT3A's own correct core molecular function (also supported by IDA/IMP), so it is accepted rather than flagged as a redundant IEA.
GO:0005783 endoplasmic reticulum	IEA GO_REF:0000044	KEEP AS NON CORE	Summary: Correct location derived from the UniProt subcellular-location vocabulary. STT3A is an ER protein, but the precise term is the ER membrane (GO:0005789); this parent term is retained as accurate but non-core.
GO:0005789 endoplasmic reticulum membrane	IEA GO_REF:0000044	ACCEPT	Summary: Core cellular location. STT3A is a multi-pass ER membrane protein (13 predicted TM helices; UniProt subcellular location "Endoplasmic reticulum membrane; Multi-pass membrane protein"). Consistent with cryo-EM structures of the ER-membrane OST-A complex. Correct and central.
GO:0009101 glycoprotein biosynthetic process	IEA GO_REF:0000002	KEEP AS NON CORE	Summary: Correct but generic InterPro-derived process term. N-linked glycosylation (GO:0006487) is a more precise descendant that is experimentally supported for STT3A. Retained as accurate but non-core.
GO:0016020 membrane	IEA GO_REF:0000002	KEEP AS NON CORE	Summary: Uninformative high-level location parent from InterPro. STT3A is more precisely an ER membrane protein (GO:0005789). Retained as accurate but non-core.
GO:0005515 protein binding	IPI PMID:21903422 Mapping a dynamic innate immunity protein interaction networ...	MARK AS OVER ANNOTATED	Summary: Bare "protein binding" IPI from a large-scale innate-immunity interaction network study (interactors include STING1/Q86WV6 and IRAK2, plus xeno Sarm1/Q6PDS3). Uninformative molecular-function term that does not describe STT3A's actual activity. Per policy, IPI evidence is not removed; flagged as an over-annotation and captured instead by the specific catalytic MF and complex-membership terms.
GO:0005515 protein binding	IPI PMID:30021884 Histone Interaction Landscapes Visualized by Crosslinking Ma...	MARK AS OVER ANNOTATED	Summary: Bare "protein binding" IPI from a histone crosslinking mass-spectrometry study (interactor RPN1/P04843, itself an OST core subunit). While the RPN1 co-purification is consistent with OST-complex membership, the term "protein binding" is uninformative. Retained (IPI not removed) but flagged as over-annotated; the biology is better captured by the OST-A complex-membership annotation.
GO:0005515 protein binding	IPI PMID:32707033 Kinase Interaction Network Expands Functional and Disease Ro...	MARK AS OVER ANNOTATED	Summary: Bare "protein binding" IPI from a large-scale kinase interactome study (interactor POMK/Q9H5K3). Uninformative MF term; retained per IPI policy but flagged as over-annotated.
GO:0005515 protein binding	IPI PMID:32814053 Interactome Mapping Provides a Network of Neurodegenerative ...	MARK AS OVER ANNOTATED	Summary: Bare "protein binding" IPI from a neurodegenerative-disease interactome study (interactors PECAM1, TGFBR2, VCP). Uninformative MF term; retained per IPI policy but flagged as over-annotated.
GO:0005515 protein binding	IPI PMID:33845483 Multilevel proteomics reveals host perturbations by SARS-CoV...	MARK AS OVER ANNOTATED	Summary: Bare "protein binding" IPI from a SARS-CoV/SARS-CoV-2 host-perturbation proteomics study (viral interactor 7b/P0DTD8). Uninformative MF term; retained per IPI policy but flagged as over-annotated.
GO:0005515 protein binding	IPI PMID:35271311 OpenCell: Endogenous tagging for the cartography of human ce...	MARK AS OVER ANNOTATED	Summary: Bare "protein binding" IPI from the OpenCell endogenous-tagging interactome (interactor RPN1/P04843, an OST core subunit). Consistent with OST-complex membership but the term is uninformative. Retained per IPI policy, flagged as over-annotated.
GO:0005515 protein binding	IPI PMID:36217030 A comprehensive SARS-CoV-2-human protein-protein interactome...	MARK AS OVER ANNOTATED	Summary: Bare "protein binding" IPI from a SARS-CoV-2-human interactome study (viral interactor 7b/P0DTD8). Uninformative MF term; retained per IPI policy but flagged as over-annotated.
GO:0004579 dolichyl-diphosphooligosaccharide-protein glycotransferase activity	TAS Reactome:R-HSA-9816276	ACCEPT	Summary: Reactome-curated (TAS) assignment of the core catalytic activity, in the context of CDH1 (E-cadherin) N-glycosylation in the ER. This is STT3A's own correct core molecular function.
GO:0005789 endoplasmic reticulum membrane	NAS PMID:31831667 Cryo-electron microscopy structures of human oligosaccharylt...	ACCEPT	Summary: ComplexPortal (NAS) location annotation citing the cryo-EM structures of human OST-A/OST-B. Correct core location; the STT3A OST complexes are ER-membrane resident. Consistent with the experimental/IEA ER-membrane annotations.
GO:0006487 protein N-linked glycosylation	NAS PMID:31831667 Cryo-electron microscopy structures of human oligosaccharylt...	ACCEPT	Summary: ComplexPortal (NAS) process annotation. Correct core biological process for STT3A/OST-A. Also supported experimentally (PMID:19167329, PMID:31296534, PMID:38670073).
GO:0008250 oligosaccharyltransferase complex	NAS PMID:31831667 Cryo-electron microscopy structures of human oligosaccharylt...	KEEP AS NON CORE	Summary: ComplexPortal (NAS) complex-membership annotation citing the OST-A/OST-B cryo-EM structures. Correct at the generic-complex level; the precise term GO:0160226 (OST-A) is annotated by IDA elsewhere. Retained as accurate but generic.
GO:0180058 protein co-translational transfer of dolichol-linked oligosaccharide	IDA PMID:31296534 Quantitative glycoproteomics reveals new classes of STT3A- a...	ACCEPT	Summary: Precise, STT3A-defining biological process: co-translational transfer of the dolichol-linked oligosaccharide onto nascent chains. Directly supported by SILAC glycoproteomics of STT3A-null cells, which established that "The STT3A complex interacts directly with the protein translocation channel to mediate cotranslational glycosylation". This is the most specific and accurate BP for STT3A and is treated as a core function. Supporting Evidence: PMID:31296534 The STT3A complex interacts directly with the protein translocation channel to mediate cotranslational glycosylation, while the STT3B complex can catalyze posttranslocational glycosylation.
GO:0005783 endoplasmic reticulum	EXP PMID:12887896 Oligosaccharyltransferase isoforms that contain different ca...	KEEP AS NON CORE	Summary: Experimental (EXP) ER localization from the study characterizing the two mammalian STT3 OST isoforms. Correct; STT3A is an ER protein. The more precise term is the ER membrane (GO:0005789), so this parent term is retained as accurate but non-core. IPI/EXP evidence is not removed.
GO:0005789 endoplasmic reticulum membrane	ISS GO_REF:0000024	ACCEPT	Summary: Sequence-similarity (ISS) transfer from the mouse ortholog (UniProtKB:P46978) of the ER membrane location. Correct core location for STT3A, corroborated by experimental and IEA annotations to the same term.
GO:0160226 oligosaccharyltransferase complex A	IDA PMID:31831667 Cryo-electron microscopy structures of human oligosaccharylt...	ACCEPT	Summary: Direct (IDA) complex-membership evidence from cryo-EM structures of the human OST-A and OST-B complexes, in which STT3A is the catalytic subunit of OST-A. This is the precise term for the STT3A-containing complex and is a core cellular-component annotation. Supporting Evidence: PMID:31831667 structural differences in the catalytic subunits STT3A and STT3B facilitate contacts to distinct OST subunits, DC2 in OST-A and MAGT1 in OST-B
GO:0160226 oligosaccharyltransferase complex A	IDA PMID:36697828 Visualization of translation and protein biogenesis at the E...	ACCEPT	Summary: Direct (IDA) evidence from cryo-EM visualization of the ER translocon, which resolved the oligosaccharyltransferase complex A (OSTA) as part of the SEC61-TRAP-OST-A translocon. Confirms STT3A membership in OST-A; core cellular component. Supporting Evidence: PMID:36697828 the protein-conducting channel SEC61, TRAP and the oligosaccharyltransferase complex A (OSTA)
GO:0160226 oligosaccharyltransferase complex A	IDA PMID:38670073 Positive selection CRISPR screens reveal a druggable pocket ...	ACCEPT	Summary: Direct (IDA) evidence; CRISPR base-editing plus cryo-EM identified STT3A as the catalytic subunit of OST-A. Core cellular-component annotation. Supporting Evidence: PMID:38670073 STT3A, the catalytic subunit of OST-A
GO:0004579 dolichyl-diphosphooligosaccharide-protein glycotransferase activity	IDA PMID:31296534 Quantitative glycoproteomics reveals new classes of STT3A- a...	ACCEPT	Summary: Direct experimental evidence (SILAC quantitative glycoproteomics of STT3A-null cells) that STT3A catalyzes transfer of the oligosaccharide onto acceptor asparagines. Core molecular function. Supporting Evidence: PMID:31296534 The ER-localized oligosaccharyltransferase (OST) transfers a preassembled oligosaccharide onto asparagine residues in acceptor sites or sequons (N-X-T/S/C, X≠P) in nascent polypeptides.
GO:0004579 dolichyl-diphosphooligosaccharide-protein glycotransferase activity	IDA PMID:38670073 Positive selection CRISPR screens reveal a druggable pocket ...	ACCEPT	Summary: Direct evidence; structure-guided studies showed NGI-1 binds the STT3A catalytic site and traps the dolichyl-PP-linked oligosaccharide donor, confirming STT3A's glycotransferase active site. Core molecular function. Supporting Evidence: PMID:38670073 NGI-1 binds the catalytic site of STT3A, where it traps a molecule of the donor substrate dolichyl-PP-GlcNAc2-Man9-Glc3
GO:0004579 dolichyl-diphosphooligosaccharide-protein glycotransferase activity	IDA PMID:39509507 Regulated N-glycosylation controls chaperone function and re...	ACCEPT	Summary: Direct evidence via structure-guided mutagenesis of the LLO-binding residues (W209, R405, Y530) that abolish OST activity, confirming STT3A's glycotransferase catalytic function. Core molecular function. Supporting Evidence: PMID:39509507 One-fifth of human proteins are N-glycosylated in the endoplasmic reticulum (ER) by two oligosaccharyltransferases, OST-A and OST-B.
GO:0006487 protein N-linked glycosylation	IDA PMID:31296534 Quantitative glycoproteomics reveals new classes of STT3A- a...	ACCEPT	Summary: Direct experimental evidence that STT3A participates in protein N-linked glycosylation; loss of the STT3A complex reduced glycosylation site occupancy at a large fraction of sequons. Core biological process. Supporting Evidence: PMID:31296534 Roughly 70% of the quantified sites showed reduced recovery in STT3A null cells
GO:0006487 protein N-linked glycosylation	IDA PMID:38670073 Positive selection CRISPR screens reveal a druggable pocket ...	ACCEPT	Summary: Direct evidence that OST-A (STT3A) is required for N-glycosylation of substrates such as TLR4, controlling their cell-surface localization. Core biological process. Supporting Evidence: PMID:38670073 the oligosaccharyltransferase complex OST-A for N-glycosylation and cell-surface localization
GO:0008250 oligosaccharyltransferase complex	IDA PMID:22467853 The oligosaccharyltransferase subunits OST48, DAD1 and KCP2 ...	KEEP AS NON CORE	Summary: Direct evidence that STT3A is part of the OST complex, from subunit-knockdown/co-complex analyses showing OST48 and DAD1 are required for assembly of STT3A-containing OST complexes. Correct; generic-complex level (precise term GO:0160226 is annotated by IDA elsewhere).
GO:0004579 dolichyl-diphosphooligosaccharide-protein glycotransferase activity	IMP PMID:22467853 The oligosaccharyltransferase subunits OST48, DAD1 and KCP2 ...	ACCEPT	Summary: Mutant/knockdown-phenotype (IMP) evidence linking STT3A-containing OST activity to N-glycosylation; depletion of shared subunits produced hypoglycosylation phenotypes for STT3A-containing complexes. Supports STT3A's core catalytic function. Experimental annotation; accepted.
GO:0006487 protein N-linked glycosylation	IMP PMID:22467853 The oligosaccharyltransferase subunits OST48, DAD1 and KCP2 ...	ACCEPT	Summary: IMP evidence that STT3A-containing OST participates in protein N-linked glycosylation (subunit depletion causes hypoglycosylation). Core biological process; accepted.
GO:0004579 dolichyl-diphosphooligosaccharide-protein glycotransferase activity	ISS GO_REF:0000024	ACCEPT	Summary: Sequence-similarity (ISS) transfer of the catalytic activity from an ortholog (UniProtKB:F1PJP5). STT3A's own correct core molecular function, independently confirmed by experimental evidence. Accepted.
GO:0008250 oligosaccharyltransferase complex	ISS GO_REF:0000024	KEEP AS NON CORE	Summary: Sequence-similarity (ISS) transfer of OST-complex membership from an ortholog. Correct at the generic-complex level; the precise OST-A term (GO:0160226) is annotated by IDA elsewhere. Retained as accurate but generic.
GO:0016020 membrane	HDA PMID:19946888 Defining the membrane proteome of NK cells.	KEEP AS NON CORE	Summary: High-throughput proteomics (HDA) detection of STT3A in an NK-cell membrane-proteome study. "Membrane" is an uninformative parent of the precise ER membrane location. Correct but generic; retained as non-core.
GO:0005789 endoplasmic reticulum membrane	TAS Reactome:R-HSA-446209	ACCEPT	Summary: Reactome-curated (TAS) ER membrane location for STT3A in the "Transfer of N-glycan to the protein" reaction. Correct core cellular location.
GO:0005789 endoplasmic reticulum membrane	TAS Reactome:R-HSA-9694793	ACCEPT	Summary: Reactome-curated (TAS) ER membrane location for STT3A in a viral (spike protein) N-glycosylation reaction. Correct core location; the substrate context is viral but the STT3A localization is accurate.
GO:0005789 endoplasmic reticulum membrane	TAS Reactome:R-HSA-9816276	ACCEPT	Summary: Reactome-curated (TAS) ER membrane location for STT3A in the CDH1 N-glycosylation reaction. Correct core location.
GO:0005789 endoplasmic reticulum membrane	TAS Reactome:R-HSA-9918962	ACCEPT	Summary: Reactome-curated (TAS) ER membrane location for STT3A in a viral (E protein) N-glycosylation reaction. Correct core location.
GO:0005789 endoplasmic reticulum membrane	TAS Reactome:R-HSA-9918988	ACCEPT	Summary: Reactome-curated (TAS) ER membrane location for STT3A in a viral (pre-M protein) N-glycosylation reaction. Correct core location.
GO:0005789 endoplasmic reticulum membrane	TAS Reactome:R-HSA-9919011	ACCEPT	Summary: Reactome-curated (TAS) ER membrane location for STT3A in a viral (pre-NS1 protein) N-glycosylation reaction. Correct core location.
GO:0005789 endoplasmic reticulum membrane	TAS Reactome:R-HSA-9931286	ACCEPT	Summary: Reactome-curated (TAS) ER membrane location for STT3A in the CD274 (PD-L1) N-glycosylation reaction. Correct core location.
GO:0004579 dolichyl-diphosphooligosaccharide-protein glycotransferase activity	IMP PMID:19167329 Cotranslational and posttranslational N-glycosylation of pol...	ACCEPT	Summary: Mutant-phenotype (IMP) evidence from isoform-specific siRNA knockdown showing STT3A is the OST catalytic subunit responsible for cotranslational glycosylation. Core molecular function. Supporting Evidence: PMID:19167329 STT3 proteins are the active site subunits of the eukaryotic OST
GO:0006487 protein N-linked glycosylation	IMP PMID:19167329 Cotranslational and posttranslational N-glycosylation of pol...	ACCEPT	Summary: IMP evidence that STT3A mediates protein N-glycosylation; STT3A knockdown caused hypoglycosylation of nascent secretory proteins. Core biological process. Supporting Evidence: PMID:19167329 The STT3A isoform is primarily responsible for cotranslational modification of sequons as the nascent polypeptide enters the lumen of the RER.
GO:0008250 oligosaccharyltransferase complex	TAS PMID:19167329 Cotranslational and posttranslational N-glycosylation of pol...	KEEP AS NON CORE	Summary: TAS evidence that STT3A is a subunit of the OST complex. Correct at the generic-complex level; the precise OST-A term (GO:0160226) is annotated by IDA elsewhere. Retained as accurate but generic.
GO:0006487 protein N-linked glycosylation	ISS GO_REF:0000024	ACCEPT	Summary: Sequence-similarity (ISS) transfer of the N-linked glycosylation process from an ortholog (UniProtKB:F1PJP5). STT3A's own correct core biological process, also supported experimentally. Accepted.

Gene Description

Existing Annotations Review

Core Functions

References

📚 Additional Documentation

Notes

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