BCCIP (BRCA2 and CDKN1A-interacting protein, also known as TOK-1) is a multifunctional nuclear protein that functions as a non-enzymatic regulator/adaptor in multiple pathways. Two major isoforms exist: BCCIPalpha (322 aa) and BCCIPbeta (314 aa) which share an N-terminal region but have distinct C-termini that adopt completely different folds, conferring isoform-specific functions. BCCIPbeta directly enhances RAD51 recombinase activity by promoting ADP release from RAD51 presynaptic filaments during homologous recombination DNA repair. BCCIPalpha inhibits FAM46/TENT5 poly(A) polymerases by binding their active site. BCCIP is also required for nucleolar recruitment of eIF6 and 12S pre-rRNA production during 60S ribosome biogenesis, consistent with its membership in the BCP1 family. During mitosis, BCCIP localizes to centrosomes and spindle poles where it participates in microtubule organization and spindle architecture. BCCIP also cooperatively enhances p21/CDKN1A-dependent inhibition of CDK2 activity.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005634 nucleus | IBA GO_REF:0000033 | ACCEPT | Summary: BCCIP is a predominantly nuclear protein with well-documented nuclear localization across multiple studies. The original TOK-1 paper (PMID:10878006) showed nuclear co-localization with p21. BCCIP colocalizes with BRCA2 in discrete nuclear foci (PMID:15713648). IBA annotation based on phylogenetic analysis is well-supported. Reason: Core function annotation. Nuclear localization is fundamental to BCCIP's multiple nuclear functions including DNA repair via BRCA2/RAD51, transcriptional regulation via p53/p21, and nucleolar ribosome biogenesis. Strongly supported by multiple independent experimental studies. Supporting Evidence: PMID:10878006 TOK-1alpha and TOK-1beta, comprising 322 and 314 amino acids, respectively, were co-localized with p21 in nuclei PMID:15713648 chromatin-bound BRCA2 colocalizes with BCCIP nuclear foci and that most radiation-induced RAD51 foci colocalize with BCCIP |
| GO:0000922 spindle pole | IEA GO_REF:0000044 | ACCEPT | Summary: BCCIP localizes to spindle poles during mitosis. This is directly demonstrated experimentally in PMID:28394342 which showed BCCIPalpha as a novel component of the mitotic spindle pole. The IEA annotation based on UniProt subcellular location is validated by experimental evidence. Reason: Well-supported localization annotation. Direct experimental evidence from PMID:28394342 shows BCCIP at spindle poles. This is a secondary localization during mitosis but accurately reflects BCCIP function in spindle organization. Supporting Evidence: PMID:28394342 we demonstrate BCCIP, especially BCCIPalpha, as a previously unidentified component of the mitotic spindle pole and the centrosome |
| GO:0005634 nucleus | IEA GO_REF:0000044 | ACCEPT | Summary: Duplicate of the IBA annotation for nuclear localization. This IEA annotation from UniProt subcellular location mapping is consistent with experimental evidence. Reason: Duplicate annotation is acceptable as it reflects independent evidence sources. Nuclear localization is core to BCCIP function. Supporting Evidence: PMID:10878006 TOK-1alpha and TOK-1beta, comprising 322 and 314 amino acids, respectively, were co-localized with p21 in nuclei |
| GO:0005813 centrosome | IEA GO_REF:0000120 | ACCEPT | Summary: BCCIP localizes to centrosomes as demonstrated experimentally in PMID:28394342. The IEA annotation is supported by direct experimental evidence showing preferential localization to the mother centriole in interphase cells. Reason: Well-supported localization annotation. Centrosome localization is part of BCCIP's role in microtubule organization and spindle assembly. Experimental evidence validates this computational annotation. Supporting Evidence: PMID:28394342 we observed a clear localization of BCCIP in both the interphase centrosome and the mitotic spindle poles |
| GO:0005814 centriole | IEA GO_REF:0000044 | ACCEPT | Summary: BCCIP preferentially localizes to the mother centriole as directly demonstrated in PMID:28394342. The IEA annotation from UniProt is validated by experimental microscopy data. Reason: Specific localization to centrioles is experimentally validated and represents a precise subcellular location for BCCIP's role in microtubule organizing center function. Supporting Evidence: PMID:28394342 BCCIP exhibits a localization bias within EB1-enriched mother centrioles |
| GO:0006281 DNA repair | IEA GO_REF:0000043 | MODIFY | Summary: BCCIP is well-established as functioning in DNA repair, specifically in homologous recombination repair of double-strand breaks. BCCIP depletion reduces HR by 20-100 fold in reporter assays and disrupts BRCA2/RAD51 foci formation (PMID:15713648). BCCIPbeta directly stimulates RAD51 recombinase activity (PMID:27694622). Reason: The annotation is correct but too general. BCCIP specifically functions in homologous recombination DNA repair, not in DNA repair broadly. A more specific term would better capture its function. Proposed replacements: double-strand break repair via homologous recombination Supporting Evidence: PMID:15713648 Reducing BCCIPalpha by 90% or BCCIPbeta by 50% by RNA interference markedly reduces RAD51 and BRCA2 foci and reduces HRR of DSBs by 20- to 100-fold file:human/BCCIP/BCCIP-deep-research-falcon.md BCCIPbeta binds DNA and physically and functionally interacts with RAD51 to stimulate its homologous DNA pairing activity |
| GO:0006974 DNA damage response | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: BCCIP functions in DNA damage response primarily through its role in homologous recombination repair. BCCIP is critical for BRCA2- and RAD51-dependent responses to DNA damage (PMID:15713648). Reason: DNA damage response is a broad term that captures BCCIP's involvement in cellular response to DNA damage. While accurate, it is not a core function annotation - the specific mechanism is homologous recombination repair via BRCA2/RAD51 interaction. Supporting Evidence: PMID:15713648 BCCIP is critical for BRCA2- and RAD51-dependent responses to DNA damage and HRR |
| GO:0005515 protein binding | IPI PMID:16189514 Towards a proteome-scale map of the human protein-protein in... | REMOVE | Summary: This annotation is from a high-throughput proteome-scale protein-protein interaction study. While BCCIP does interact with many proteins, GO:0005515 (protein binding) is an uninformative term that does not describe specific molecular function. Reason: Per GO curation guidelines, GO:0005515 (protein binding) is uninformative and should not be used. BCCIP has well-characterized specific binding activities (e.g., RAD51, BRCA2, p21/CDKN1A, FAM46/TENT5, tubulins) that should be annotated with more specific terms instead. Supporting Evidence: PMID:16189514 Towards a proteome-scale map of the human protein-protein interaction network. |
| GO:0005515 protein binding | IPI PMID:17353931 Large-scale mapping of human protein-protein interactions by... | REMOVE | Summary: Another protein binding annotation from a large-scale mass spectrometry interaction study. This uninformative term does not convey BCCIP's specific functional interactions. Reason: GO:0005515 (protein binding) should be avoided. BCCIP's specific protein interactions are well-characterized and should be annotated with appropriate specific terms. Supporting Evidence: PMID:17353931 Large-scale mapping of human protein-protein interactions by mass spectrometry. |
| GO:0005515 protein binding | IPI PMID:25416956 A proteome-scale map of the human interactome network. | REMOVE | Summary: From a proteome-scale human interactome network study. Generic protein binding annotation without functional specificity. Reason: Uninformative annotation. GO:0005515 should be replaced with specific binding terms that reflect BCCIP's actual molecular interactions. Supporting Evidence: PMID:25416956 A proteome-scale map of the human interactome network. |
| GO:0005515 protein binding | IPI PMID:32296183 A reference map of the human binary protein interactome. | REMOVE | Summary: From a reference human binary protein interactome study. Generic protein binding annotation from high-throughput interactome mapping. Reason: GO:0005515 (protein binding) is uninformative per GO guidelines and should not be propagated without more specific functional context. Supporting Evidence: PMID:32296183 Apr 8. A reference map of the human binary protein interactome. |
| GO:0005515 protein binding | IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling... | REMOVE | Summary: Dual proteome-scale networks study showing cell-specific interactome remodeling. Generic protein binding annotation. Reason: Uninformative GO:0005515 annotation. BCCIP has well-characterized specific binding partners that warrant specific molecular function terms. Supporting Evidence: PMID:33961781 2021 May 6. Dual proteome-scale networks reveal cell-specific remodeling of the human interactome. |
| GO:0000226 microtubule cytoskeleton organization | IEA GO_REF:0000107 | ACCEPT | Summary: IEA annotation based on orthology transfer from mouse. This is experimentally validated in PMID:28394342 which demonstrated BCCIP's role in microtubule organization and anchoring at centrosomes and spindle poles. Reason: Well-supported annotation. BCCIP is required for microtubule organizing and anchoring activities. BCCIP depletion leads to defects in microtubule organization, reduced tubulin acetylation, and spindle abnormalities (PMID:28394342). Supporting Evidence: PMID:28394342 BCCIP deficiency compromises spindle assembly independent of microtubule nucleation |
| GO:0007052 mitotic spindle organization | IEA GO_REF:0000107 | ACCEPT | Summary: IEA annotation from orthology. Experimentally validated in PMID:28394342 which showed BCCIP depletion leads to spindle defects and disorientation. Reason: Core mitotic function. BCCIP, particularly BCCIPalpha, is critical for spindle architecture and orientation. This is experimentally demonstrated with IMP evidence in PMID:28394342. Supporting Evidence: PMID:28394342 We find that BCCIP depletion leads to morphological defects, disoriented mitotic spindles, chromosome congression defects and delayed mitotic progression |
| GO:0034453 microtubule anchoring | IEA GO_REF:0000107 | ACCEPT | Summary: Orthology-based annotation that is validated experimentally. PMID:28394342 demonstrates BCCIP's role in microtubule anchoring at centrosomes. Reason: Validated annotation. BCCIP participates in microtubule anchoring at centrosomes and spindle poles, as demonstrated by experimental evidence in PMID:28394342. Supporting Evidence: PMID:28394342 We demonstrate that BCCIP localizes proximal to the mother centriole and participates in microtubule organization and then redistributes to the spindle pole to ensure faithful spindle architecture |
| GO:0097431 mitotic spindle pole | IEA GO_REF:0000107 | ACCEPT | Summary: Orthology-based localization annotation validated by direct experimental evidence in PMID:28394342 showing BCCIP at spindle poles. Reason: Well-supported localization. BCCIP redistributes to spindle poles during mitosis as part of its function in ensuring faithful spindle architecture. Supporting Evidence: PMID:28394342 we demonstrate BCCIP, especially BCCIPalpha, as a previously unidentified component of the mitotic spindle pole |
| GO:0005654 nucleoplasm | IDA GO_REF:0000052 | ACCEPT | Summary: IDA annotation based on immunofluorescence curation (HPA). Consistent with nuclear localization demonstrated in multiple studies. Reason: Appropriate localization annotation consistent with BCCIP's nuclear functions in DNA repair, transcriptional regulation, and ribosome biogenesis. Supporting Evidence: PMID:10878006 TOK-1alpha and TOK-1beta, comprising 322 and 314 amino acids, respectively, were co-localized with p21 in nuclei |
| GO:0003677 DNA binding | IDA PMID:27694622 The Ξ²-isoform of BCCIP promotes ADP release from the RAD51 p... | ACCEPT | Summary: PMID:27694622 demonstrated that purified BCCIPbeta binds DNA directly. This DNA binding activity was shown through biochemical assays as part of characterizing BCCIP's role in homologous recombination. Reason: Experimentally validated molecular function. BCCIPbeta binds DNA as part of its role in stimulating RAD51-mediated homologous DNA pairing. Supporting Evidence: file:human/BCCIP/BCCIP-deep-research-falcon.md BCCIPbeta binds DNA and physically and functionally interacts with RAD51 PMID:27694622 2016 Sep 30. The Ξ²-isoform of BCCIP promotes ADP release from the RAD51 presynaptic filament and enhances homologous DNA pairing. |
| GO:0005515 protein binding | IPI PMID:27694622 The Ξ²-isoform of BCCIP promotes ADP release from the RAD51 p... | REMOVE | Summary: From the Kelso et al. 2017 study characterizing BCCIPbeta-RAD51 interaction. While the interaction is real, GO:0005515 is uninformative. The study specifically demonstrates RAD51 binding. Reason: GO:0005515 is uninformative. This study specifically characterized BCCIPbeta's interaction with RAD51 - a more specific term for this interaction would be appropriate rather than generic protein binding. Supporting Evidence: PMID:27694622 2016 Sep 30. The Ξ²-isoform of BCCIP promotes ADP release from the RAD51 presynaptic filament and enhances homologous DNA pairing. |
| GO:0042802 identical protein binding | IPI PMID:27694622 The Ξ²-isoform of BCCIP promotes ADP release from the RAD51 p... | ACCEPT | Summary: PMID:27694622 demonstrated that BCCIPbeta forms homodimers through gel filtration experiments. This self-association is functionally relevant. Reason: Experimentally validated molecular function. BCCIPbeta homodimerization was directly demonstrated in the Kelso et al. 2017 study. Supporting Evidence: file:human/BCCIP/BCCIP-deep-research-falcon.md BCCIPbeta is a homodimer that promotes ADP release from the RAD51 presynaptic filament PMID:27694622 2016 Sep 30. The Ξ²-isoform of BCCIP promotes ADP release from the RAD51 presynaptic filament and enhances homologous DNA pairing. |
| GO:0005515 protein binding | IPI PMID:28931820 The non-canonical poly(A) polymerase FAM46C acts as an onco-... | REMOVE | Summary: From a study on FAM46C/TENT5C as an onco-suppressor in multiple myeloma. BCCIP was identified as interacting with TENT5C. The UniProt annotation notes that this interaction has no effect on TENT5C poly(A) polymerase function (for BCCIPbeta). Reason: GO:0005515 is uninformative. The specific interaction with TENT5C is notable - BCCIPalpha inhibits FAM46/TENT5 activity while BCCIPbeta does not affect it. A more specific term would be appropriate. Supporting Evidence: PMID:28931820 The non-canonical poly(A) polymerase FAM46C acts as an onco-suppressor in multiple myeloma. |
| GO:0000226 microtubule cytoskeleton organization | IMP PMID:28394342 Regulation of spindle integrity and mitotic fidelity by BCCI... | ACCEPT | Summary: Direct experimental evidence from the Huhn et al. 2017 study. IMP (inferred from mutant phenotype) annotation based on BCCIP knockdown/depletion studies showing microtubule organization defects. Reason: Core function with strong experimental evidence. BCCIP depletion causes defects in microtubule organization at spindle poles and centrosomes. Supporting Evidence: PMID:28394342 BCCIP deficiency compromises spindle assembly independent of microtubule nucleation |
| GO:0005813 centrosome | IDA PMID:28394342 Regulation of spindle integrity and mitotic fidelity by BCCI... | ACCEPT | Summary: Direct experimental evidence showing BCCIP localization to centrosomes via microscopy in PMID:28394342. Reason: Primary experimental evidence for centrosome localization. BCCIP (especially BCCIPalpha) is a component of the centrosome and participates in microtubule organization from this location. Supporting Evidence: PMID:28394342 we demonstrate BCCIP, especially BCCIPalpha, as a previously unidentified component of the mitotic spindle pole and the centrosome |
| GO:0005814 centriole | IDA PMID:28394342 Regulation of spindle integrity and mitotic fidelity by BCCI... | ACCEPT | Summary: Direct experimental evidence showing preferential BCCIP localization to the mother centriole in interphase cells. Reason: Primary experimental evidence for centriole localization with specific detail about mother centriole preference. Supporting Evidence: PMID:28394342 BCCIP exhibits a localization bias within EB1-enriched mother centrioles |
| GO:0007052 mitotic spindle organization | IMP PMID:28394342 Regulation of spindle integrity and mitotic fidelity by BCCI... | ACCEPT | Summary: IMP evidence based on BCCIP depletion causing spindle defects including disorientation and morphological abnormalities. Reason: Core mitotic function with strong experimental evidence. BCCIP depletion leads to disoriented spindles and spindle architecture defects. Supporting Evidence: PMID:28394342 We find that BCCIP depletion leads to morphological defects, disoriented mitotic spindles, chromosome congression defects and delayed mitotic progression |
| GO:0034453 microtubule anchoring | IMP PMID:28394342 Regulation of spindle integrity and mitotic fidelity by BCCI... | ACCEPT | Summary: IMP evidence from BCCIP depletion studies showing defects in microtubule anchoring at centrosomes. Reason: Experimentally validated function. BCCIP participates in microtubule anchoring as demonstrated by phenotypic analysis. Supporting Evidence: PMID:28394342 We demonstrate that BCCIP localizes proximal to the mother centriole and participates in microtubule organization and then redistributes to the spindle pole to ensure faithful spindle architecture |
| GO:0090307 mitotic spindle assembly | IMP PMID:28394342 Regulation of spindle integrity and mitotic fidelity by BCCI... | ACCEPT | Summary: IMP evidence based on spindle assembly defects upon BCCIP depletion. Study established BCCIP as a novel regulator of spindle assembly. Reason: Core mitotic function. BCCIP cooperates with the dynein epistatic group to ensure faithful spindle assembly and mitosis fidelity. Supporting Evidence: PMID:28394342 our study has established BCCIP as a previously unidentified regulator of spindle assembly that cooperates with the dynein epistatic group to ensure the fidelity of mitosis |
| GO:0097431 mitotic spindle pole | IDA PMID:28394342 Regulation of spindle integrity and mitotic fidelity by BCCI... | ACCEPT | Summary: Direct experimental evidence for BCCIP localization at mitotic spindle poles via microscopy. Reason: Primary experimental evidence for spindle pole localization. This is essential for BCCIP's role in spindle organization. Supporting Evidence: PMID:28394342 we demonstrate BCCIP, especially BCCIPalpha, as a previously unidentified component of the mitotic spindle pole |
| GO:0003723 RNA binding | HDA PMID:22658674 Insights into RNA biology from an atlas of mammalian mRNA-bi... | ACCEPT | Summary: HDA annotation from the Castello et al. 2012 mRNA interactome capture study in HeLa cells. BCCIP was identified among 860 proteins qualifying as RNA-binding proteins by UV crosslinking and mass spectrometry. This RNA binding activity is consistent with BCCIP's established role in 60S ribosome biogenesis where it is required for 12S pre-rRNA production. Reason: RNA binding is a core molecular function underlying BCCIP's role in ribosome biogenesis. BCCIP belongs to the BCP1 family and is required for 12S pre-rRNA production during 60S subunit biogenesis. The HDA identification likely reflects this functional role. Supporting Evidence: file:human/BCCIP/BCCIP-deep-research-falcon.md BCCIP is required for nucleolar recruitment of eIF6 and 12S pre-rRNA production during 60S ribosome biogenesis PMID:22658674 May 31. Insights into RNA biology from an atlas of mammalian mRNA-binding proteins. |
| GO:0061101 neuroendocrine cell differentiation | IDA PMID:18440304 LYRIC/AEG-1 overexpression modulates BCCIPalpha protein leve... | MARK AS OVER ANNOTATED | Summary: From PMID:18440304 which studied LYRIC/AEG-1 interaction with BCCIP. The authors observed that overexpression of BCCIPalpha in DU145 prostate tumor cells induced apparent neuroendocrine differentiation as a phenotypic observation. Reason: This appears to be an over-annotation based on an incidental observation in a tumor cell line context rather than a core biological function of BCCIP. The study was focused on LYRIC/AEG-1 modulation of BCCIP levels, and the neuroendocrine differentiation observation was noted as a coincidental finding. This is not a conserved or core function of BCCIP. Supporting Evidence: file:human/BCCIP/BCCIP-deep-research-falcon.md BCCIPalpha overexpression in prostate tumor cells induced apparent neuroendocrine differentiation PMID:18440304 LYRIC/AEG-1 overexpression modulates BCCIPalpha protein levels in prostate tumor cells. |
| GO:0000079 regulation of cyclin-dependent protein serine/threonine kinase activity | IDA PMID:10878006 TOK-1, a novel p21Cip1-binding protein that cooperatively en... | ACCEPT | Summary: From the original TOK-1 discovery paper (PMID:10878006). TOK-1alpha/BCCIPalpha enhanced p21-dependent inhibition of CDK2 kinase activity through formation of a ternary complex with p21 and CDK2. Reason: Core function from the founding paper characterizing BCCIP/TOK-1. BCCIPalpha cooperatively enhances p21-dependent inhibitory activity toward CDK2, making this a well-validated regulatory function. Supporting Evidence: PMID:10878006 TOK-1alpha enhanced the inhibitory activity of p21 toward histone H1 kinase activity of CDK2. TOK-1alpha is thus thought to be a new type of CDK2 modulator. |
| GO:0019207 kinase regulator activity | IDA PMID:10878006 TOK-1, a novel p21Cip1-binding protein that cooperatively en... | ACCEPT | Summary: BCCIP/TOK-1alpha functions as a kinase regulator by enhancing p21-dependent CDK2 inhibition, as demonstrated in the original characterization paper. Reason: Core molecular function. BCCIPalpha modulates CDK2 kinase activity indirectly through its interaction with p21/CDKN1A, enhancing inhibition of CDK2. Supporting Evidence: PMID:10878006 TOK-1alpha is thus thought to be a new type of CDK2 modulator |
| GO:0019908 nuclear cyclin-dependent protein kinase holoenzyme complex | IDA PMID:10878006 TOK-1, a novel p21Cip1-binding protein that cooperatively en... | ACCEPT | Summary: BCCIP/TOK-1alpha forms a ternary complex with p21 and active CDK2. This complex localization was demonstrated in the original paper. Reason: Experimentally validated complex component. BCCIPalpha binds to active CDK2 via p21 to form a ternary complex in human cells. Supporting Evidence: PMID:10878006 TOK-1alpha also preferentially bound to an active form of cyclin-dependent kinase 2 (CDK2) via p21, and these made a ternary complex in human cells |
| GO:0005515 protein binding | IPI PMID:18440304 LYRIC/AEG-1 overexpression modulates BCCIPalpha protein leve... | REMOVE | Summary: From the study on LYRIC/AEG-1 and BCCIP interaction. Demonstrates interaction with MTDH/LYRIC protein. GO:0005515 is uninformative. Reason: GO:0005515 (protein binding) should be avoided. The specific interaction with MTDH/LYRIC is documented but generic protein binding annotation is not informative. Supporting Evidence: PMID:18440304 LYRIC/AEG-1 overexpression modulates BCCIPalpha protein levels in prostate tumor cells. |
| GO:0000079 regulation of cyclin-dependent protein serine/threonine kinase activity | TAS PMID:10878006 TOK-1, a novel p21Cip1-binding protein that cooperatively en... | ACCEPT | Summary: TAS annotation for the same function as the IDA annotation above. Traceable Author Statement based on the original TOK-1 characterization. Reason: Duplicate annotation with different evidence code is acceptable. Core regulatory function of BCCIP. Supporting Evidence: PMID:10878006 TOK-1alpha enhanced the inhibitory activity of p21 toward histone H1 kinase activity of CDK2 |
| GO:0005634 nucleus | TAS PMID:10878006 TOK-1, a novel p21Cip1-binding protein that cooperatively en... | ACCEPT | Summary: TAS annotation for nuclear localization based on the original characterization paper. Third annotation for nuclear localization with different evidence type. Reason: Consistent with multiple other annotations for nuclear localization. TAS evidence from the founding paper. Supporting Evidence: PMID:10878006 TOK-1alpha and TOK-1beta, comprising 322 and 314 amino acids, respectively, were co-localized with p21 in nuclei |
| GO:0042273 ribosomal large subunit biogenesis | IMP PMID:33245766 BCCIP is required for nucleolar recruitment of eIF6 and 12S ... | NEW | Summary: BCCIP is required for nucleolar recruitment of eIF6 and 12S pre-rRNA production during 60S ribosome biogenesis, as demonstrated in Ye et al. 2020 (NAR). BCCIP is the metazoan homolog of yeast Bcp1, a 60S biogenesis factor. Reason: This is a well-characterized function of BCCIP that is missing from current annotations. BCCIP belongs to the BCP1 family and is required for nucleolar eIF6 recruitment and 12S pre-rRNA production for 60S subunit biogenesis. Supporting Evidence: file:human/BCCIP/BCCIP-deep-research-falcon.md BCCIP is required for nucleolar recruitment of eIF6 and 12S pre-rRNA production during 60S ribosome biogenesis PMID:33245766 BCCIP is required for nucleolar recruitment of eIF6 and 12S pre-rRNA production during 60S ribosome biogenesis. |
| GO:0005730 nucleolus | IDA PMID:33245766 BCCIP is required for nucleolar recruitment of eIF6 and 12S ... | NEW | Summary: BCCIP localizes to nucleoli through an acidic N-terminal motif that drives nucleolar localization. This is required for its function in 60S ribosome biogenesis. Reason: Nucleolar localization is functionally important for BCCIP's role in ribosome biogenesis and is missing from current annotations. An acidic N-terminal motif drives this localization. Supporting Evidence: file:human/BCCIP/BCCIP-deep-research-falcon.md An acidic N-terminal motif in BCCIP drives nucleolar localization and is required to recruit eIF6 to nucleoli PMID:33245766 BCCIP is required for nucleolar recruitment of eIF6 and 12S pre-rRNA production during 60S ribosome biogenesis. |
| GO:1905168 positive regulation of double-strand break repair via homologous recombination | IMP PMID:15713648 The BRCA2-interacting protein BCCIP functions in RAD51 and B... | NEW | Summary: BCCIPbeta directly enhances RAD51 recombinase activity by promoting ADP release from RAD51 presynaptic filaments. BCCIP depletion reduces HR by 20-100 fold and disrupts BRCA2/RAD51 foci formation. Reason: This is a core function of BCCIP that should be specifically annotated. BCCIPbeta positively regulates HR through direct enhancement of RAD51 activity. Supporting Evidence: file:human/BCCIP/BCCIP-deep-research-falcon.md BCCIPbeta binds DNA and physically and functionally interacts with RAD51 to stimulate its homologous DNA pairing activity PMID:15713648 The BRCA2-interacting protein BCCIP functions in RAD51 and BRCA2 focus formation and homologous recombinational repair. PMID:27694622 2016 Sep 30. The Ξ²-isoform of BCCIP promotes ADP release from the RAD51 presynaptic filament and enhances homologous DNA pairing. |
| GO:0015631 tubulin binding | IDA PMID:28394342 Regulation of spindle integrity and mitotic fidelity by BCCI... | NEW | Summary: Both BCCIP isoforms interact with alpha-, beta- and gamma-tubulins as demonstrated in PMID:28394342. This underlies BCCIP's role in microtubule organization. Reason: UniProt lists tubulin binding as an annotated function. Both isoforms bind tubulins, supporting BCCIP's role at centrosomes and spindle poles. Supporting Evidence: PMID:28394342 dynactin and BCCIP were associated with a complex that contained centrosomal gamma-tubulin and alpha/beta-tubulin dimers |
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Download this section (compressed HTML)Q: What is the relative contribution of the two BCCIP isoforms to each of its multiple functions (HR, ribosome biogenesis, spindle assembly, CDK regulation)?
Q: Does BCCIP's role in 60S ribosome biogenesis contribute to its tumor suppressor function, and is this separable from its DNA repair role?
Q: What is the physiological significance of BCCIPalpha inhibition of FAM46/TENT5 poly(A) polymerases?
Experiment: Isoform-specific rescue experiments in BCCIP knockout cells to determine which functions are dependent on alpha vs beta isoforms
Experiment: Structural studies to understand how the dramatically different folds of BCCIPalpha and BCCIPbeta confer distinct functions despite sharing most of their sequence
What is not known β curated, literature-grounded statements of the open unknowns (the inverse of core functions).
Gap: The GO representation and physiological scope of BCCIPalpha-mediated FAM46/TENT5 inhibition remain unresolved.
NARROWING BIOLOGYCURATION MF_DARK
What is known: The review already captures BCCIPbeta RAD51 regulation, ribosome biogenesis, spindle assembly, and p21/CDK2 regulation as core functions. BCCIPalpha inhibition of FAM46/TENT5 poly(A) polymerases is a strong isoform-specific mechanism, but it has not yet been integrated into the core-function block or mapped to a specific GO molecular function.
Significance: Resolving this gap would determine whether BCCIPalpha should be annotated as a negative regulator/adaptor of noncanonical poly(A) polymerase activity, and whether the current broad RNA-binding representation should be refined for this isoform-specific activity.
What would resolve it: Isoform-specific curation should connect the structural FAM46/TENT5 inhibition evidence to direct cellular substrates and decide whether the activity warrants a new molecular-function annotation, a process annotation, or both.
Provenance (the field's own admissions):
Gap: How BCCIP's isoform-specific activities are coordinated across DNA repair, RNA metabolism, ribosome biogenesis, spindle assembly, and CDK regulation remains incompletely understood.
OPEN BIOLOGYCURATION BP_DARK
What is known: Individual activities are supported well enough to retain as core or non-core functions. The unresolved issue is whether these are separable pathway-specific functions, manifestations of a common scaffold/adaptor role, or context-dependent functions of distinct isoforms.
Significance: Resolving this gap would clarify which biological-process annotations are primary for BCCIP, which are isoform-specific, and which are downstream consequences of perturbing an essential multifunctional factor.
What would resolve it: Isoform-specific rescue, separation-of-function mutants, time-resolved localization, and pathway-specific substrate/partner assays should distinguish shared from independent mechanisms.
Provenance (the field's own admissions):
Gap: BCCIP's cancer biology remains context-dependent: partial loss can promote genome instability and tumor initiation, while retained or elevated BCCIP activity may support proliferation in some established cancers.
OPEN BIOLOGYCURATION BP_DARK
What is known: The review treats genome-maintenance and ribosome-biogenesis functions as molecular/cellular activities. It does not infer a single tumor-suppressor or oncogenic GO process annotation from disease-context observations.
Significance: Resolving this gap would determine whether cancer-context annotations are appropriate for BCCIP, and would prevent over-annotation from mixing tumor initiation, tumor maintenance, essentiality, and proliferation-support effects.
What would resolve it: Dose- and isoform-resolved perturbation across tumor-initiation and established-tumor models should separate genome-instability effects from dependencies on DNA repair, ribosome biogenesis, and spindle function.
Provenance (the field's own admissions):
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