TRAF2 is best established as a receptor-associated signaling adaptor that recruits cIAP ubiquitin ligases and coordinates NF-kappaB/JNK signaling. Its membership in ubiquitin-ligase complexes is much more secure than a universal assignment of autonomous E3 activity. Immune-cell process annotations can be correct even when the catalytic assignment remains disputed.
This is a manual literature investigation of human Q12933, paired with horse F7BIV4. Falcon and Perplexity-lite attempts failed; this file is not a provider-generated report. Sources were checked in the publication cache, with new PMID records fetched through the repository publication fetcher. Europe PMC searches covered TRAF2 E3/cIAP mechanisms and CD40/B-cell antibody responses; QuickGO definitions were checked for signaling adaptor activity, TNF binding, T-cell cytokine production and regulation of immunoglobulin production. Abstract-only records are identified below. Human and horse UniProt sequences were compared reproducibly in the linked analysis.
Human TRAF2 is a 501-residue RING/zinc-finger protein with a C-terminal coiled-coil/TRAF receptor-binding region. The human–horse comparison covers all 501 human residues at 92.0% paired identity; the selected 516-residue horse protein retains the major domains. The horse insertion around residues 272–280 lies after aligned human position 265 and does not delete the receptor-binding domain. This supports transfer of the adaptor mechanism, but is not a reciprocal-orthology test, a residue-by-residue binding-site assay or verification of the original ProtNLM input sequence. Sequence analysis · Human UniProt · Horse UniProt
The original TRADD study separates recruitment of TRAF2 from recruitment of FADD: these branches couple TNFR1 to NF-kappaB and cell-death machinery. A later purified-domain study reconstitutes the cIAP1 BIR1–TRAF2 coiled-coil complex, maps binding residues and identifies one cIAP-binding unit per TRAF trimer. This is direct evidence for recruitment of a catalytic partner rather than an inference from an electronic enzyme label. PMID:8565075(https://pubmed.ncbi.nlm.nih.gov/8565075/), DOI 10.1016/S0092-8674(00)80984-8; PMID:20447407(https://pubmed.ncbi.nlm.nih.gov/20447407/), DOI 10.1016/j.jmb.2010.04.055. Both cached records are abstract-only, but the abstracts explicitly describe the relevant interactions and reconstitution.
Recombinant human TRAF proteins tested against the CD40 cytoplasmic tail show direct TRAF2 binding. The shared TRAF1/2/3 site was mapped to PVQET. The study distinguishes direct binding from indirect recruitment of TRAF5 in hetero-oligomers. This is strong support for CD40 receptor binding and receptor-complex membership. PMID:9718306(https://pubmed.ncbi.nlm.nih.gov/9718306/), DOI 10.1021/bi981067q, abstract-only.
The 2009 RING/zinc-finger structure finds a TRAF2 interface incompatible with the TRAF6-like Ubc13 interaction, including an insertion and unfavorable interface residues. The study reports lack of E2 interaction and argues that associated cIAPs can supply ubiquitin ligase activity. Its full text is cached. PMID:19810754(https://pubmed.ncbi.nlm.nih.gov/19810754/), DOI 10.1021/bi901462e.
The 2010 S1P study explicitly reproduces the absence of RIP1 ubiquitination without S1P, then reports rescue by S1P in a purified reaction. It reports activity with recombinant TRAF2 purified from insect cells, checks for cIAP1/2 contamination, directly assays S1P binding and reports S1P-stimulated autoubiquitination. Its full text is cached. This is substantive positive biochemical evidence and cannot be dismissed simply because the preceding structure suggested an inactive fold. Conversely, it does not establish cofactor-independent activity in every receptor context. PMID:20577214(https://pubmed.ncbi.nlm.nih.gov/20577214/), DOI 10.1038/nature09128.
TRAF2 is also an experimentally established substrate of cIAP1: cIAP1 binds TRAF1 and TRAF2 but ubiquitinates TRAF2 in the TNFR2 study. Therefore, observation of ubiquitinated TRAF2 does not independently establish autoubiquitination. PMID:11907583(https://pubmed.ncbi.nlm.nih.gov/11907583/), DOI 10.1038/416345a, abstract-only.
The GbetaL/MLST8 study reports TRAF2-dependent K63 ubiquitination, impaired SIN1 association and redistribution toward mTORC1 instead of mTORC2. Its full text supports the cellular assembly outcomes; these do not resolve the universal autonomous-E3 question. PMID:28489822(https://pubmed.ncbi.nlm.nih.gov/28489822/), DOI 10.1038/nature22344. The NLRC5 study likewise supports TRAF2-associated ubiquitination signaling in an innate-immune context. PMID:26620909(https://pubmed.ncbi.nlm.nih.gov/26620909/), DOI 10.1083/jcb.201505091.
The review therefore retains process participation and complex membership while leaving intrinsic ubiquitin transfer and autoubiquitination UNDECIDED. A decisive follow-up would reconcile preparation, E2, substrate and lipid-cofactor conditions in independently reproduced defined reactions.
The BCL10/MALT1 paper's title highlights TRAF6, but its abstract explicitly reports TRAF2 RNAi reducing TCR-dependent IKK activation and IL-2 production. This directly supports a TRAF2 cytokine-production role; the title is not evidence of paralog misattribution. PMID:15125833(https://pubmed.ncbi.nlm.nih.gov/15125833/), DOI 10.1016/s1097-2765(04)00236-9, abstract-only.
For immunoglobulin regulation, shared CD40 TRAF2/3-site mutant studies alone do not isolate TRAF2 from TRAF3. The more discriminating mouse CD40 C-terminal-tail study uses an alternative TRAF2-binding site and reports retained antibody isotype switching and affinity maturation despite loss of germinal centers. Together with direct human TRAF2–CD40 binding this supports a broad mammalian humoral-regulatory role, while leaving precise species/isotype responses open. PMID:12354380(https://pubmed.ncbi.nlm.nih.gov/12354380/); PMID:17360936(https://pubmed.ncbi.nlm.nih.gov/17360936/), DOI 10.1182/blood-2006-07-038414. These records are abstract-only; the latter has a PMC identifier but full text could not be retrieved by the fetcher.
CD40 mutant experiments also distinguish canonical and noncanonical NF-kappaB outputs through TRAF2/5. CD27 experiments identify recruitment of TRAF2 and SHP-1 during naive T-cell activation and memory programming. These are receptor- and cell-state-specific deployments of the same scaffold, not interchangeable evidence for every inflammatory pathway. PMID:15708970(https://pubmed.ncbi.nlm.nih.gov/15708970/), DOI 10.1073/pnas.0500187102; PMID:38354704(https://pubmed.ncbi.nlm.nih.gov/38354704/), DOI 10.1016/j.immuni.2024.01.011.
TNF versus TNF receptor binding. QuickGO defines GO:0043120 as binding the cytokine. The full EVER2/TRADD study concerns recruitment of TRAF2/RIPK1 into TNFR1 complex I. Recovery of intracellular TRAF2 through a ligand-bound receptor complex is insufficient to demonstrate direct TNF contact. The binding annotation remains UNDECIDED pending resolution of the exact curated interaction, rather than being treated as equivalent to receptor binding. PMID:23429285(https://pubmed.ncbi.nlm.nih.gov/23429285/), DOI 10.1038/cddis.2013.27; QuickGO definition.
TRAF2 in a TRAF6-focused paper. The TIFAB full text assays TRAF2-driven NF-kappaB as a TNFR2 comparison, and explicitly contrasts it with TLR/TRAF6 signaling. The positive NF-kappaB result supports that annotation; direct TLR-pathway participation is not resolved by the comparison alone and remains UNDECIDED. PMID:26458771(https://pubmed.ncbi.nlm.nih.gov/26458771/), DOI 10.1084/jem.20141898.
TRAF2 in a TRAF1-focused paper. The gasdermin-D abstract highlights TRAF1, but the full text directly assays TRAF2: it enhances GD-NT ubiquitination and restores cytolytic activity of tagged GD-NT. The authors did not detect direct TRAF2–GD-NT interaction and discuss an indirect TRAF1/2 mechanism. Positive regulation of pyroptosis is supported as a non-core experimental context, without inferring direct substrate binding or intrinsic E3 chemistry. PMID:40097387(https://pubmed.ncbi.nlm.nih.gov/40097387/), DOI 10.1038/s41419-025-07475-6.
Interaction density. The human snapshot contains 708 rows, including 513 generic protein-binding assertions. Many belong to systematic interaction maps. The review preserves each row and its partner/source identity; most generic interactions remain UNDECIDED because the specific experimental record was not traced. Verified cIAP/TRADD recruitment is expressed with signaling adaptor activity. This is a substantial remaining evidence-audit workload, not a claim that the interaction maps are wrong.
IRE1 binds TRAF2 and connects ER stress to JNK; a human bladder-cell study directly reports IRE1–TRAF2–ASK1 complex formation. GSTP1 binds TRAF2 and restrains TRAF2–ASK1 signaling independently of GST catalytic activity. TCPTP–TRAF2 interaction regulates selective TNF/Src/ERK signaling. These primary mechanisms support informative partner-binding and complex annotations. PMID:10650002(https://pubmed.ncbi.nlm.nih.gov/10650002/), DOI 10.1126/science.287.5453.664; PMID:23000344(https://pubmed.ncbi.nlm.nih.gov/23000344/), DOI 10.1016/j.cellsig.2012.09.012; PMID:16636664(https://pubmed.ncbi.nlm.nih.gov/16636664/), DOI 10.1038/sj.onc.1209576; PMID:15696169(https://pubmed.ncbi.nlm.nih.gov/15696169/), DOI 10.1038/ni1169.
The human review does not treat every distal phenotype, subcellular pool or high-throughput interaction as core. Horse ProtNLM predictions are judged against primary mammalian mechanisms plus the selected protein's architecture, with COR meaning supported and absent from frozen horse GOA. Model training membership is unknown. No horse-specific mechanistic publication or reviewed horse SwissProt entry was identified to justify another external horse research job.