ABTB1 is an ankyrin-repeat and BTB/POZ-domain protein with multiple splice isoforms and reported cytoplasmic and nuclear pools. It was originally described as BPOZ/elongation factor 1A-binding protein and as a PTEN-responsive growth-suppressive factor in cancer cell assays. Its domain architecture, CUL3 interaction, and reported TdT, eEF1A1, and NLRP3 substrate relationships support a role as the BPOZ-2 substrate-recognition component of Cul3-RING ubiquitin ligase complexes; the full physiological substrate repertoire remains incompletely characterized.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000151 ubiquitin ligase complex | IBA GO_REF:0000033 | MODIFY | Summary: ABTB1 has BTB/POZ and ankyrin-repeat architecture and is linked to CUL3 in interaction data. The existing IBA ubiquitin-ligase-complex call is directionally sound, but the more informative complex context is a Cul3-RING ubiquitin ligase complex rather than the broad parent term. Reason: The PANTHER IBA and local UniProt/GOA evidence support ubiquitin ligase complex membership, and UniProt lists an ABTB1-CUL3 interaction. Because ABTB1 is a BTB/POZ-domain protein and the PN projection places it in the Cul3 substrate receptor branch, the appropriate replacement is the specific CRL3 complex term. ABTB1 should still not be assigned the catalytic E3 ligase activity that belongs to the RING subunit, but the substrate papers now separately support the noncatalytic substrate-adaptor molecular function. Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH Sources checked: PANTHER:PTN001974461 · PAINT ABTB1/Btb3p ancestry node SUPPORTS TRANSFER Supports ABTB1 placement in the ubiquitin-ligase-complex branch, but the broad parent term is less informative than Cul3-RING ubiquitin ligase complex. PomBase:SPAC13D6.04c · S. pombe btb3 SUPPORTS TRANSFER Fission yeast Btb3p supports the conserved BTB/Cul3 complex relationship used by the IBA. Proposed replacements: Cul3-RING ubiquitin ligase complex Supporting Evidence: file:human/ABTB1/ABTB1-uniprot.txt Q969K4; Q13618: CUL3; NbExp=5 PMID:21145461 a large fraction of cullins are assembled with adaptor modules file:human/ABTB1/ABTB1-notes.md For ABTB1, local evidence supports BTB/POZ/ankyrin architecture, CUL3 interaction, and inferred ubiquitin ligase complex membership file:human/ABTB1/ABTB1-deep-research-falcon.md Geyer et al. propose that BTB/POZ proteins act as **substrate-specific adaptors** for CUL3 ubiquitin ligases |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | ACCEPT | Summary: Cytoplasmic localization is consistent with UniProt subcellular-location curation and the HPA/GOA localization context. Reason: ABTB1 is curated by UniProt as cytoplasmic, and the same cellular compartment is represented by independent GOA localization rows. This is a supported location for the protein, although no compartment-specific substrate has been established. Supporting Evidence: file:human/ABTB1/ABTB1-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: This UniProt subcellular-location mapping is consistent with direct UniProt curation of ABTB1 as cytoplasmic. Reason: The IEA row is a conservative mapping from UniProt subcellular-location vocabulary and agrees with the IBA cytoplasm and HPA cytosol context. Supporting Evidence: file:human/ABTB1/ABTB1-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0005515 protein binding | IPI PMID:21145461 Dynamics of cullin-RING ubiquitin ligase network revealed by... | MODIFY | Summary: PMID:21145461 is the CRL-network proteomics study underlying the ABTB1-CUL3 interaction in GOA/UniProt. The generic protein-binding term should be replaced by the more specific CUL3/cullin-binding term. Reason: ABTB1-CUL3 association is informative for the proposed CRL3 complex context, but generic protein binding is not an informative molecular-function annotation. The appropriate replacement captures cullin-family protein binding, with substrate-adaptor activity captured on a separate, substrate-supported GO:1990756 row. Proposed replacements: cullin family protein binding Supporting Evidence: file:human/ABTB1/ABTB1-uniprot.txt Q969K4; Q13618: CUL3; NbExp=5 PMID:21145461 the abundance of adaptor modules, rather than cycles of neddylation and CAND1 binding, drives CRL network organization |
| GO:0005515 protein binding | IPI PMID:25416956 A proteome-scale map of the human interactome network. | REMOVE | Summary: This is a proteome-scale human interactome study. ABTB1 interaction evidence from this source is useful as interaction context, but the GO term protein binding is too generic to describe ABTB1's function. Reason: The annotation reports high-throughput interaction evidence, including partners such as CUL3 and EEF1A2 in GOA. For ABTB1, the informative curation target is the specific CUL3/cullin-binding and CRL3-complex context; generic protein binding should not be retained as a core molecular function. Supporting Evidence: PMID:25416956 A proteome-scale map of the human interactome network |
| GO:0005515 protein binding | IPI PMID:28514442 Architecture of the human interactome defines protein commun... | REMOVE | Summary: PMID:28514442 reports BioPlex AP-MS interaction mapping. ABTB1 interactions from this source are high-throughput network context rather than a specific biochemical activity. Reason: GOA records this as generic protein binding for several ABTB1 partners. The term does not capture ABTB1's validated CRL3 substrate-adaptor role or any specific partner mechanism, so it should be removed. Supporting Evidence: PMID:28514442 BioPlex 2.0 enables systems-level study of protein interactions |
| GO:0005515 protein binding | IPI PMID:31515488 Extensive disruption of protein interactions by genetic vari... | REMOVE | Summary: PMID:31515488 contributes high-throughput human protein-interaction evidence, including variant-sensitive interaction context. It does not make generic protein binding an informative ABTB1 function. Reason: The reported physical interactions are not disputed, but generic protein binding is uninformative and should not be retained as ABTB1's molecular function. |
| GO:0005515 protein binding | IPI PMID:32296183 A reference map of the human binary protein interactome. | REMOVE | Summary: PMID:32296183 is a reference human binary-interactome map. The ABTB1 row is useful as interaction context but not as a specific molecular-function claim. Reason: Generic protein binding from a large-scale interactome map is not informative for ABTB1. No specific GO molecular function should be inferred from this row beyond partner-level curation when the partner and mechanism justify it. Supporting Evidence: PMID:32296183 A reference map of the human binary protein interactome |
| GO:0005515 protein binding | IPI PMID:32814053 Interactome Mapping Provides a Network of Neurodegenerative ... | REMOVE | Summary: This neurodegenerative-disease interactome study contributes ABTB1 interaction context, including ATXN1/TARDBP partners in GOA, but does not establish a core ABTB1 molecular function. Reason: The interaction context is peripheral to the supported ABTB1 CRL3/cytoplasmic complex picture. Generic protein binding is uninformative and should not be retained as a core function. |
| GO:0005515 protein binding | IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling... | REMOVE | Summary: PMID:33961781 reports dual proteome-scale interaction networks. This supports high-throughput interaction context but not a specific ABTB1 molecular function. Reason: ABTB1 partners from this dataset are best treated as network context. The generic protein-binding annotation is too broad and should not be a core annotation. Supporting Evidence: PMID:33961781 defining interactome structure and dynamics is required to understand cellular diversity |
| GO:0005515 protein binding | IPI PMID:40205054 Multimodal cell maps as a foundation for structural and func... | REMOVE | Summary: PMID:40205054 is a multimodal cell-map resource integrating protein interactions and imaging. Its ABTB1 interaction evidence is contextual and does not justify retaining generic protein binding. Reason: The study is valuable for cell-map context, but protein binding remains an uninformative term for ABTB1. This row does not establish any specific ABTB1 substrate or interaction mechanism. Supporting Evidence: PMID:40205054 yielding protein biophysical interactions and protein IF images for a matched set of more than 5,100 proteins |
| GO:0005829 cytosol | IDA GO_REF:0000052 | ACCEPT | Summary: HPA-derived cytosol localization is consistent with the broader UniProt cytoplasm annotation. Reason: Cytosol is a reasonable supported cellular component for ABTB1 and is compatible with the proposed cytoplasmic CRL3-associated context. Supporting Evidence: file:human/ABTB1/ABTB1-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0005737 cytoplasm | EXP PMID:11494141 Growth-suppressive effects of BPOZ and EGR2, two genes invol... | ACCEPT | Summary: The original BPOZ/PTEN paper is cited by UniProt for ABTB1 cytoplasmic localization. The cached publication is abstract-only, so the UniProt record is used as local support for this localization statement. Reason: Cytoplasmic localization is repeatedly represented in ABTB1 curated sources. This localization is valid, while the paper's growth-suppression phenotype should not be over-translated into a detailed GO process without source-level full text. Supporting Evidence: file:human/ABTB1/ABTB1-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:1990756 ubiquitin-like ligase-substrate adaptor activity | IDA PMID:18429817 Bood POZ containing gene type 2 is a human counterpart of ye... | NEW | Summary: NEW annotation. Canonical ABTB1/BPOZ-2 binds CUL3 and bridges Cul3-RING ubiquitin ligase complexes to substrate proteins, with direct evidence for TdT, eEF1A1, and NLRP3 ubiquitination or degradation. Reason: The OpenScientist follow-up overturned the previous conservative no-substrate boundary. Maezawa et al. showed BPOZ-2-CUL3 interaction, ternary TdT-BPOZ-2-CUL3 complex formation, and BPOZ-2/CUL3-promoted TdT ubiquitination or degradation; Koiwai et al. mapped eEF1A1 binding to ABTB1 ankyrin and BTB/POZ domains and showed BPOZ-2-promoted eEF1A1 ubiquitination/degradation; Li et al. showed BPOZ-2-dependent NLRP3 degradation through CUL3. Supporting Evidence: PMID:18429817 TdT, BPOZ-2, and CUL3 formed a ternary complex in vivo. TdT was ubiquitinated only within the nucleus and degraded by the 26S proteasome. PMID:22808041 We show here that TdT is ubiquitylated by the Cul3-based ubiquitylation system in vitro. PMID:18459963 BPOZ-2 promoted eEF1A1 ubiquitylation and degradation, suggesting that eEF1A1 is a substrate of BPOZ-2. PMID:36936774 BPOZ-2 interacted with NLRP3 and mediated its degradation by recruiting Cullin 3. |
| GO:0016567 protein ubiquitination | IDA PMID:18429817 Bood POZ containing gene type 2 is a human counterpart of ye... | NEW | Summary: NEW annotation. ABTB1/BPOZ-2 participates in Cul3-dependent substrate ubiquitination as the receptor/adaptor that recruits TdT, eEF1A1, and NLRP3 to ubiquitination/degradation pathways. Reason: ABTB1's contribution is substrate recruitment rather than catalytic ubiquitin transfer, but that recruitment is a direct step in protein ubiquitination. The TdT papers show BPOZ-2/CUL3 ternary complex formation and Cul3-based TdT ubiquitylation, Koiwai et al. show BPOZ-2-promoted eEF1A1 ubiquitylation, and Li et al. show BPOZ-2-mediated NLRP3 degradation through CUL3. Supporting Evidence: PMID:18429817 TdT, BPOZ-2, and CUL3 formed a ternary complex in vivo. TdT was ubiquitinated only within the nucleus and degraded by the 26S proteasome. PMID:22808041 We show here that TdT is ubiquitylated by the Cul3-based ubiquitylation system in vitro. PMID:18459963 BPOZ-2 promoted eEF1A1 ubiquitylation and degradation, suggesting that eEF1A1 is a substrate of BPOZ-2. PMID:36936774 BPOZ-2 interacted with NLRP3 and mediated its degradation by recruiting Cullin 3. |
| GO:0005634 nucleus | IDA PMID:18429817 Bood POZ containing gene type 2 is a human counterpart of ye... | NEW | Summary: NEW annotation. ABTB1/BPOZ-2 has a nuclear pool, and the TdT ubiquitination work places BPOZ-2-dependent CUL3 activity in the nucleus. Reason: Maezawa et al. reported BPOZ-2 ubiquitination by CUL3 mainly in the nucleus, nuclear accumulation after 26S-proteasome inhibition, possible recruitment from the cytoplasm to the nucleus, and TdT ubiquitination only within the nucleus, supporting nucleus as a conditionally occupied ABTB1 compartment in addition to its cytoplasmic/cytosolic annotations. Supporting Evidence: PMID:18429817 BPOZ-2 itself was ubiquitinated through the CUL3-based E3 ligase mainly within the nucleus and degraded by the 26S proteasome. Although BPOZ-2 was mainly expressed within the cytoplasm, it accumulated within the nucleus in the presence of the specific 26S proteasome inhibitor MG132. BPOZ-2 may be recruited to the nucleus from the cytoplasm. |
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Download this section (compressed HTML)Q: Which ABTB1/BPOZ-2 substrate relationships occur at endogenous expression levels in physiological human cell types, and which are specific to overexpression, viral, or cancer perturbation contexts?
Suggested experts: GO ubiquitin-proteasome curators, Proteostasis Network UPS curators
Q: Should TdT-, eEF1A1-, or NLRP3-specific ABTB1 evidence drive conservative biological-process annotations beyond the substrate-adaptor molecular function?
Suggested experts: GO biological-process editors
Q: Are the EEF1A/EEF1D interactions a biologically meaningful ABTB1 function or a non-core interaction context from interactome datasets, and should the UniProt-only translation elongation factor activity IEA be treated as an erroneous keyword mapping?
Suggested experts: UniProt curators, translation-factor specialists
Q: Given that ABTB1 is a direct miR-125b target and an anti-proliferative factor in myeloid models, yet higher ABTB1 expression correlates with worse progression-free survival in prostate cancer, are these context- or isoform-dependent roles, and should any of them map to a defensible GO biological-process term rather than remaining as correlative disease context?
Suggested experts: GO biological-process editors, cancer biology curators
Experiment: Test miR-125b-dependent regulation of endogenous ABTB1 across cell types using miR-125b mimic/inhibitor with ABTB1 mRNA/protein readouts and 3'UTR reporter controls, then assess whether ABTB1 restoration reverses miR-125b-driven proliferation.
Hypothesis: miR-125b post-transcriptionally represses ABTB1 to relieve its anti-proliferative activity, and this axis operates in non-myeloid contexts such as prostate epithelium.
Type: regulatory axis validation
Experiment: Perform ABTB1 affinity purification under native expression or low-level tagged rescue, quantify CUL3/RBX1 association, and combine ABTB1 knockout or degron-stabilization proteomics with neddylation inhibition to identify candidate ABTB1-dependent substrates.
Hypothesis: ABTB1 is a substrate-recognition subunit of a CUL3-RBX1 ubiquitin ligase complex.
Type: CRL3 substrate identification
Experiment: Reconstitute ABTB1, CUL3-RBX1, and candidate substrates in vitro and test ternary complex formation plus substrate ubiquitination, using ABTB1 BTB/POZ-domain mutants as CUL3-binding controls.
Hypothesis: ABTB1 directly bridges CUL3 to one or more substrate proteins.
Type: substrate-bridging assay
Experiment: Validate ABTB1 interactions with EEF1A2 and EEF1D by reciprocal co-IP at endogenous expression levels and test whether ABTB1 perturbation changes elongation-factor localization, stability, or translation output.
Hypothesis: EEF1A/EEF1D interactions represent a reproducible but non-core ABTB1 interaction context.
Type: interaction specificity review
What is not known — curated, literature-grounded statements of the open unknowns (the inverse of core functions).
Gap: The endogenous, tissue-specific ABTB1/BPOZ-2 substrate repertoire remains incompletely resolved.
OPEN BIOLOGY BP_DARK
What is known: The review accepts cullin family protein binding, Cul3-RING ubiquitin ligase complex membership, and ubiquitin-like ligase-substrate adaptor activity based on TdT, eEF1A1, and NLRP3 evidence. It does not yet assign every reported disease or stress phenotype as a direct ABTB1 biological process.
Significance: Resolving this gap would determine which substrate-specific biological processes, if any, should be assigned based on the substrates ABTB1 recruits in physiological cell types.
What would resolve it: Endogenous ABTB1-CUL3 complex isolation, substrate-trapping mutants, quantitative ubiquitin-remnant proteomics, and in vitro ternary-complex and ubiquitination assays should separate native substrates from overexpression or disease-context interactors.
Provenance (the field's own admissions):
Gap: How ABTB1's cytoplasmic and nuclear pools are regulated and matched to endogenous substrates remains incompletely resolved.
OPEN BIOLOGYCURATION CC_DARK
What is known: UniProt and the review support cytoplasmic/cytosolic context, while the TdT/BPOZ-2 paper places BPOZ-2 CUL3 activity and TdT ubiquitination in the nucleus under 26S-proteasome inhibition. The review now accepts both cytoplasmic/cytosolic and nuclear pools but does not resolve which endogenous substrates are recruited in each compartment.
Significance: Better localization evidence would refine cellular-component annotations and distinguish a generic cytoplasmic adaptor from a specific CRL3, translation factor, or signaling compartment.
What would resolve it: Endogenous tagging or validated antibodies should map ABTB1 localization under basal, PTEN/miRNA, cell-cycle, and proteasome/neddylation-perturbation conditions with CUL3 and candidate substrate colocalization.
Provenance (the field's own admissions):
Gap: ABTB1's anti-proliferative/PTEN-linked role and prostate-cancer expression association remain mechanistically and contextually unresolved.
OPEN BIOLOGYCURATION BP_DARK
What is known: The review accepts that ABTB1 has been linked to PTEN growth-suppressive signaling and is directly regulated by miR-125b in myeloid models, but it does not annotate ABTB1 to a specific cell-cycle, cancer, or signaling biological process from correlative or context-dependent evidence.
Significance: Resolving this gap would determine whether any proliferation, PTEN-pathway, miRNA-regulated, or cancer-relevant GO process is a direct ABTB1 function, or whether these findings remain disease-model context downstream of an unknown substrate/scaffold mechanism.
What would resolve it: Isoform-resolved ABTB1 perturbation and rescue across myeloid and prostate models, combined with substrate identification and PTEN/AR/miRNA pathway epistasis, should define which phenotypes are direct.
Provenance (the field's own admissions):
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