ABRAXAS2

UniProt ID: Q15018
Organism: Homo sapiens
Review Status: COMPLETE
Aliases:
ABRO1 FAM175B KIAA0157
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Gene Description

ABRAXAS2 encodes Abraxas 2/ABRO1, a noncatalytic MPN-domain scaffold subunit of the BRISC K63-linked deubiquitinating complex. Together with BRCC3/BRCC36, BABAM1/MERIT40, and BABAM2/BRE, ABRAXAS2 helps assemble and localize BRISC in the cytoplasm and nucleus, where the complex removes K63-linked ubiquitin chains from substrates involved in immune receptor signaling and mitotic spindle organization. ABRAXAS2 also provides the BRISC-specific interface for SHMT2-dependent regulation and targeting, and it can translocate to the nucleus during cellular stress to influence p53-dependent DNA-damage signaling. Unlike ABRAXAS1, ABRAXAS2 lacks the BRCA1-interacting C-terminal phospho-motif and is not a canonical BRCA1-A DNA-repair adaptor.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0005634 nucleus
IBA
GO_REF:0000033
ACCEPT
Summary: Nuclear localization is supported as a minor/stress-induced pool.
Reason: Although ABRAXAS2 is mainly cytoplasmic, several studies report nuclear localization or nuclear translocation during DNA damage/oxidative stress, so nucleus annotations are acceptable when not interpreted as BRCA1-A complex membership [PMID:22974638; PMID:25283148].
Supporting Evidence:
PMID:25283148
DNA-damage induced accumulation of endogenous ABRO1 as well as translocation of ABRO1 to the nucleus
PMID:22974638
during cellular stress it enters the nucleus and co-localizes with ATF4
PMID:24075985
presence of the BRISC-SHMT complex in both the cytoplasm and nucleus
GO:0008017 microtubule binding
IBA
GO_REF:0000033
ACCEPT
Summary: microtubule binding is supported by ABRAXAS2/BRISC localization to mitotic microtubule structures and functional spindle defects after BRISC depletion.
Reason: PMID:26195665 directly shows ABRAXAS2/BRISC binds microtubules, localizes to K-fiber minus ends and spindle poles, and promotes bipolar spindle assembly through NUMA1 deubiquitination. This is an experimentally supported ABRAXAS2 cellular role rather than a generic cell-cycle phenotype.
Supporting Evidence:
PMID:26195665
BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
PMID:26195665
promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
GO:0008608 attachment of spindle microtubules to kinetochore
IBA
GO_REF:0000033
ACCEPT
Summary: attachment of spindle microtubules to kinetochore is supported by ABRAXAS2/BRISC localization to mitotic microtubule structures and functional spindle defects after BRISC depletion.
Reason: PMID:26195665 directly shows ABRAXAS2/BRISC binds microtubules, localizes to K-fiber minus ends and spindle poles, and promotes bipolar spindle assembly through NUMA1 deubiquitination. This is an experimentally supported ABRAXAS2 cellular role rather than a generic cell-cycle phenotype.
Supporting Evidence:
PMID:26195665
BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
PMID:26195665
promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
GO:0031593 polyubiquitin modification-dependent protein binding
IBA
GO_REF:0000033
MARK AS OVER ANNOTATED
Summary: ABRAXAS2 participates in a K63-ubiquitin-directed BRISC complex, but direct polyubiquitin-dependent binding should not be treated as an independently enabled ABRAXAS2 molecular function.
Reason: The term is related to the K63-ubiquitin substrate-recognition biology of BRISC, but ABRAXAS2 is best interpreted as a noncatalytic scaffold/adaptor within the complex. The over-annotation concern is specifically that this annotation says ABRAXAS2 individually enables polyubiquitin-dependent binding, whereas the stronger evidence is that the BRISC complex processes K63-linked ubiquitin chains. The core annotation should emphasize BRISC complex membership and participation in K63-linked deubiquitination contexts rather than direct enabling of polyubiquitin-dependent binding by ABRAXAS2 itself.
Supporting Evidence:
PMID:19214193
the activity was intrinsic to PA700 and the Brcc36 isopeptidase complex (BRISC)
PMID:20656690
KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
PMID:31253574
Both BRCC36-containing complexes are specific for lysine-63-linked ubiquitin (K63-Ub) chains
GO:0090307 mitotic spindle assembly
IBA
GO_REF:0000033
ACCEPT
Summary: mitotic spindle assembly is supported by ABRAXAS2/BRISC localization to mitotic microtubule structures and functional spindle defects after BRISC depletion.
Reason: PMID:26195665 directly shows ABRAXAS2/BRISC binds microtubules, localizes to K-fiber minus ends and spindle poles, and promotes bipolar spindle assembly through NUMA1 deubiquitination. This is an experimentally supported ABRAXAS2 cellular role rather than a generic cell-cycle phenotype.
Supporting Evidence:
PMID:26195665
BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
PMID:26195665
promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
GO:0000922 spindle pole
IEA
GO_REF:0000044
ACCEPT
Summary: Spindle-pole localization is supported by mitotic imaging.
Reason: ABRAXAS2/BRISC localizes to centrosomes and spindle poles during mitosis [PMID:26195665].
Supporting Evidence:
PMID:26195665
ABRO1 was shown to be located at the centrosomes in interphase
PMID:26195665
BRISC localizes at centrosomes, spindle poles, and midbody during mitosis.
GO:0005634 nucleus
IEA
GO_REF:0000044
ACCEPT
Summary: Nuclear localization is supported as a minor/stress-induced pool.
Reason: Although ABRAXAS2 is mainly cytoplasmic, several studies report nuclear localization or nuclear translocation during DNA damage/oxidative stress, so nucleus annotations are acceptable when not interpreted as BRCA1-A complex membership [PMID:22974638; PMID:25283148].
Supporting Evidence:
PMID:25283148
DNA-damage induced accumulation of endogenous ABRO1 as well as translocation of ABRO1 to the nucleus
PMID:22974638
during cellular stress it enters the nucleus and co-localizes with ATF4
PMID:24075985
presence of the BRISC-SHMT complex in both the cytoplasm and nucleus
GO:0005737 cytoplasm
IEA
GO_REF:0000044
ACCEPT
Summary: Cytoplasmic localization is well supported.
Reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
Supporting Evidence:
PMID:20656690
KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
PMID:21282113
ABRO1 is mainly localized in the cytoplasm.
GO:0005856 cytoskeleton
IEA
GO_REF:0000044
MODIFY
Summary: Cytoskeleton is directionally correct but too broad for the available evidence.
Reason: ABRAXAS2/BRISC is specifically associated with microtubule structures, especially spindle poles and K-fiber minus ends. The broader cytoskeleton term should be replaced with microtubule/spindle-related components.
Proposed replacements: microtubule spindle pole
Supporting Evidence:
PMID:26195665
ABRO1 was shown to be located at the centrosomes in interphase
PMID:26195665
BRISC localizes at centrosomes, spindle poles, and midbody during mitosis.
GO:0005515 protein binding
IPI
PMID:19615732
Defining the human deubiquitinating enzyme interaction lands...
REMOVE
Summary: Generic protein-binding annotation from interaction-screen data.
Reason: GO:0005515 does not describe ABRAXAS2 function. These interaction datasets may be useful as evidence for physical partners, but ABRAXAS2 should instead be represented by specific BRISC complex, K63-linked deubiquitination, microtubule, or pathway annotations when supported.
Supporting Evidence:
PMID:19615732
We identified 774 candidate interacting proteins associated with 75 Dubs.
GO:0005515 protein binding
IPI
PMID:32296183
A reference map of the human binary protein interactome.
REMOVE
Summary: Generic protein-binding annotation from interaction-screen data.
Reason: GO:0005515 does not describe ABRAXAS2 function. These interaction datasets may be useful as evidence for physical partners, but ABRAXAS2 should instead be represented by specific BRISC complex, K63-linked deubiquitination, microtubule, or pathway annotations when supported.
Supporting Evidence:
PMID:32296183
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: Generic protein-binding annotation from interaction-screen data.
Reason: GO:0005515 does not describe ABRAXAS2 function. These interaction datasets may be useful as evidence for physical partners, but ABRAXAS2 should instead be represented by specific BRISC complex, K63-linked deubiquitination, microtubule, or pathway annotations when supported.
Supporting Evidence:
PMID:33961781
Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.
GO:0005515 protein binding
IPI
PMID:36115835
Quantitative fragmentomics allow affinity mapping of interac...
REMOVE
Summary: Generic protein-binding annotation from interaction-screen data.
Reason: GO:0005515 does not describe ABRAXAS2 function. These interaction datasets may be useful as evidence for physical partners, but ABRAXAS2 should instead be represented by specific BRISC complex, K63-linked deubiquitination, microtubule, or pathway annotations when supported.
Supporting Evidence:
PMID:36115835
Quantitative fragmentomics allow affinity mapping of interactomes.
GO:0005515 protein binding
IPI
PMID:37398436
AI-guided pipeline for protein-protein interaction drug disc...
REMOVE
Summary: Generic protein-binding annotation from interaction-screen data.
Reason: GO:0005515 does not describe ABRAXAS2 function. These interaction datasets may be useful as evidence for physical partners, but ABRAXAS2 should instead be represented by specific BRISC complex, K63-linked deubiquitination, microtubule, or pathway annotations when supported.
Supporting Evidence:
PMID:37398436
AI-guided pipeline for protein-protein interaction drug discovery identifies a SARS-CoV-2 inhibitor.
GO:0005829 cytosol
IDA
GO_REF:0000052
ACCEPT
Summary: Cytosol localization is consistent with ABRAXAS2 as a major cytosolic BRISC scaffold.
Reason: Multiple studies describe ABRAXAS2/ABRO1/KIAA0157 as mainly cytoplasmic/cytosolic, while also allowing stress-induced nuclear pools.
Supporting Evidence:
PMID:20656690
KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
PMID:21282113
ABRO1 is mainly localized in the cytoplasm.
GO:0005634 nucleus
EXP
PMID:21282113
NBA1/MERIT40 and BRE interaction is required for the integri...
ACCEPT
Summary: Nuclear localization is supported as a minor/stress-induced pool.
Reason: Although ABRAXAS2 is mainly cytoplasmic, several studies report nuclear localization or nuclear translocation during DNA damage/oxidative stress, so nucleus annotations are acceptable when not interpreted as BRCA1-A complex membership [PMID:22974638; PMID:25283148].
Supporting Evidence:
PMID:25283148
DNA-damage induced accumulation of endogenous ABRO1 as well as translocation of ABRO1 to the nucleus
PMID:22974638
during cellular stress it enters the nucleus and co-localizes with ATF4
PMID:24075985
presence of the BRISC-SHMT complex in both the cytoplasm and nucleus
GO:0005634 nucleus
EXP
PMID:22974638
ATF4 interacts with Abro1/KIAA0157 scaffold protein and part...
ACCEPT
Summary: Nuclear localization is supported as a minor/stress-induced pool.
Reason: Although ABRAXAS2 is mainly cytoplasmic, several studies report nuclear localization or nuclear translocation during DNA damage/oxidative stress, so nucleus annotations are acceptable when not interpreted as BRCA1-A complex membership [PMID:22974638; PMID:25283148].
Supporting Evidence:
PMID:25283148
DNA-damage induced accumulation of endogenous ABRO1 as well as translocation of ABRO1 to the nucleus
PMID:22974638
during cellular stress it enters the nucleus and co-localizes with ATF4
PMID:24075985
presence of the BRISC-SHMT complex in both the cytoplasm and nucleus
GO:0005634 nucleus
EXP
PMID:24075985
A BRISC-SHMT complex deubiquitinates IFNAR1 and regulates in...
ACCEPT
Summary: Nuclear localization is supported as a minor/stress-induced pool.
Reason: Although ABRAXAS2 is mainly cytoplasmic, several studies report nuclear localization or nuclear translocation during DNA damage/oxidative stress, so nucleus annotations are acceptable when not interpreted as BRCA1-A complex membership [PMID:22974638; PMID:25283148].
Supporting Evidence:
PMID:25283148
DNA-damage induced accumulation of endogenous ABRO1 as well as translocation of ABRO1 to the nucleus
PMID:22974638
during cellular stress it enters the nucleus and co-localizes with ATF4
PMID:24075985
presence of the BRISC-SHMT complex in both the cytoplasm and nucleus
GO:0005634 nucleus
EXP
PMID:25283148
ABRO1 suppresses tumourigenesis and regulates the DNA damage...
ACCEPT
Summary: Nuclear localization is supported as a minor/stress-induced pool.
Reason: Although ABRAXAS2 is mainly cytoplasmic, several studies report nuclear localization or nuclear translocation during DNA damage/oxidative stress, so nucleus annotations are acceptable when not interpreted as BRCA1-A complex membership [PMID:22974638; PMID:25283148].
Supporting Evidence:
PMID:25283148
DNA-damage induced accumulation of endogenous ABRO1 as well as translocation of ABRO1 to the nucleus
PMID:22974638
during cellular stress it enters the nucleus and co-localizes with ATF4
PMID:24075985
presence of the BRISC-SHMT complex in both the cytoplasm and nucleus
GO:0005737 cytoplasm
EXP
PMID:20656690
The Lys63-specific deubiquitinating enzyme BRCC36 is regulat...
ACCEPT
Summary: Cytoplasmic localization is well supported.
Reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
Supporting Evidence:
PMID:20656690
KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
PMID:21282113
ABRO1 is mainly localized in the cytoplasm.
GO:0005737 cytoplasm
EXP
PMID:21282113
NBA1/MERIT40 and BRE interaction is required for the integri...
ACCEPT
Summary: Cytoplasmic localization is well supported.
Reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
Supporting Evidence:
PMID:20656690
KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
PMID:21282113
ABRO1 is mainly localized in the cytoplasm.
GO:0005737 cytoplasm
EXP
PMID:22974638
ATF4 interacts with Abro1/KIAA0157 scaffold protein and part...
ACCEPT
Summary: Cytoplasmic localization is well supported.
Reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
Supporting Evidence:
PMID:20656690
KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
PMID:21282113
ABRO1 is mainly localized in the cytoplasm.
GO:0005737 cytoplasm
EXP
PMID:25283148
ABRO1 suppresses tumourigenesis and regulates the DNA damage...
ACCEPT
Summary: Cytoplasmic localization is well supported.
Reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
Supporting Evidence:
PMID:20656690
KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
PMID:21282113
ABRO1 is mainly localized in the cytoplasm.
GO:0005737 cytoplasm
IPI
PMID:31253574
Structural Basis of BRCC36 Function in DNA Repair and Immune...
ACCEPT
Summary: Cytoplasmic localization is well supported.
Reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
Supporting Evidence:
PMID:20656690
KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
PMID:21282113
ABRO1 is mainly localized in the cytoplasm.
GO:0005737 cytoplasm
NAS
PMID:31253574
Structural Basis of BRCC36 Function in DNA Repair and Immune...
ACCEPT
Summary: Cytoplasmic localization is well supported.
Reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
Supporting Evidence:
PMID:20656690
KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
PMID:21282113
ABRO1 is mainly localized in the cytoplasm.
GO:0034516 response to vitamin B6
NAS
PMID:31142841
Metabolic control of BRISC-SHMT2 assembly regulates immune s...
MODIFY
Summary: Vitamin B6/PLP regulates SHMT2 oligomer state and thus BRISC-SHMT2 assembly, but ABRAXAS2 is not best described as executing a vitamin B6 response.
Reason: The supported ABRAXAS2 process in this study is BRISC-SHMT2-dependent positive regulation of type I interferon signaling. PLP is the metabolite that shifts SHMT2 dimer/tetramer state and thereby modulates BRISC-SHMT2 interaction; annotating ABRAXAS2 itself to response to vitamin B6 overstates the causal process. The same ComplexPortal NAS annotation may merit reassessment for the other BRISC subunits annotated from this study.
Supporting Evidence:
PMID:31142841
Intracellular levels of PLP regulate the interaction between BRISC and SHMT2, as well as inflammatory cytokine responses.
PMID:31142841
Mutations in BRISC that disrupt SHMT2 binding impair type I interferon signalling in response to inflammatory stimuli.
GO:0070552 BRISC complex
IPI
PMID:31253574
Structural Basis of BRCC36 Function in DNA Repair and Immune...
ACCEPT
Summary: ABRAXAS2 is a bona fide BRISC complex subunit.
Reason: Multiple biochemical, structural, UniProt, and ComplexPortal sources identify ABRAXAS2/ABRO1 as the BRISC-specific scaffold paired with BRCC36/BRCC3, BABAM1/MERIT40, and BABAM2/BRE. This is the safest PN-projected annotation and is already in GOA.
Supporting Evidence:
PMID:21282113
ABRO1 complex does not interact with BRCA1
PMID:31253574
in BRCA1-A, BRCC36 is supported by ABRAXAS (Wang et al., 2007), whereas in BRISC, it is paired with ABRO1
file:human/ABRAXAS2/ABRAXAS2-deep-research-falcon.md
**ABRAXAS2/ABRO1 is a core scaffold subunit of BRISC**
GO:0070552 BRISC complex
NAS
PMID:31253574
Structural Basis of BRCC36 Function in DNA Repair and Immune...
ACCEPT
Summary: ABRAXAS2 is a bona fide BRISC complex subunit.
Reason: Multiple biochemical, structural, UniProt, and ComplexPortal sources identify ABRAXAS2/ABRO1 as the BRISC-specific scaffold paired with BRCC36/BRCC3, BABAM1/MERIT40, and BABAM2/BRE. This is the safest PN-projected annotation and is already in GOA.
Supporting Evidence:
PMID:21282113
ABRO1 complex does not interact with BRCA1
PMID:31253574
in BRCA1-A, BRCC36 is supported by ABRAXAS (Wang et al., 2007), whereas in BRISC, it is paired with ABRO1
GO:0005515 protein binding
IPI
PMID:26195665
The deubiquitinating enzyme complex BRISC is required for pr...
REMOVE
Summary: Generic protein-binding annotation for the ABRAXAS2/NUMA1 interaction.
Reason: The interaction is biologically important, but GO:0005515 is uninformative. The same paper supports the more specific ABRAXAS2/BRISC roles in microtubule binding, mitotic spindle assembly, and K63-linked deubiquitination of NUMA1 [PMID:26195665].
Supporting Evidence:
PMID:26195665
BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
PMID:26195665
promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
GO:0005829 cytosol
TAS
Reactome:R-HSA-5691439
ACCEPT
Summary: Cytosol localization is consistent with ABRAXAS2 as a major cytosolic BRISC scaffold.
Reason: Multiple studies describe ABRAXAS2/ABRO1/KIAA0157 as mainly cytoplasmic/cytosolic, while also allowing stress-induced nuclear pools.
Supporting Evidence:
Reactome:R-HSA-5691439
FAM175B (ABRO1), another BRISC subunit, binds directly to NLRP3 leading to FAM175B-dependent recruitment of the BRISC complex
GO:0000278 mitotic cell cycle
IMP
PMID:26195665
The deubiquitinating enzyme complex BRISC is required for pr...
MODIFY
Summary: Mitotic cell cycle is supported but too broad relative to the specific spindle defects.
Reason: ABRAXAS2/BRISC depletion affects mitosis through spindle assembly, kinetochore-microtubule attachment, and chromosome segregation. More specific existing terms capture this biology better than the broad mitotic cell cycle term.
Supporting Evidence:
PMID:26195665
BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
PMID:26195665
promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
GO:0005737 cytoplasm
IDA
PMID:24075985
A BRISC-SHMT complex deubiquitinates IFNAR1 and regulates in...
ACCEPT
Summary: Cytoplasmic localization is well supported.
Reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
Supporting Evidence:
PMID:20656690
KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
PMID:21282113
ABRO1 is mainly localized in the cytoplasm.
GO:0005813 centrosome
IDA
PMID:26195665
The deubiquitinating enzyme complex BRISC is required for pr...
ACCEPT
Summary: Centrosome colocalization is experimentally supported in mitotic-cell imaging.
Reason: ABRAXAS2/BRISC localizes to centrosomes and spindle poles during the cell cycle [PMID:26195665].
Supporting Evidence:
PMID:26195665
ABRO1 was shown to be located at the centrosomes in interphase
PMID:26195665
BRISC localizes at centrosomes, spindle poles, and midbody during mitosis.
GO:0007059 chromosome segregation
IMP
PMID:26195665
The deubiquitinating enzyme complex BRISC is required for pr...
ACCEPT
Summary: Chromosome-segregation defects follow ABRAXAS2/BRISC depletion.
Reason: ABRAXAS2 depletion produces lagging chromosomes and spindle defects, supporting involvement in chromosome segregation through its spindle assembly role [PMID:26195665].
Supporting Evidence:
PMID:26195665
BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
PMID:26195665
promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
GO:0008017 microtubule binding
IDA
PMID:26195665
The deubiquitinating enzyme complex BRISC is required for pr...
ACCEPT
Summary: microtubule binding is supported by ABRAXAS2/BRISC localization to mitotic microtubule structures and functional spindle defects after BRISC depletion.
Reason: PMID:26195665 directly shows ABRAXAS2/BRISC binds microtubules, localizes to K-fiber minus ends and spindle poles, and promotes bipolar spindle assembly through NUMA1 deubiquitination. This is an experimentally supported ABRAXAS2 cellular role rather than a generic cell-cycle phenotype.
Supporting Evidence:
PMID:26195665
BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
PMID:26195665
promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
GO:0008608 attachment of spindle microtubules to kinetochore
IMP
PMID:26195665
The deubiquitinating enzyme complex BRISC is required for pr...
ACCEPT
Summary: attachment of spindle microtubules to kinetochore is supported by ABRAXAS2/BRISC localization to mitotic microtubule structures and functional spindle defects after BRISC depletion.
Reason: PMID:26195665 directly shows ABRAXAS2/BRISC binds microtubules, localizes to K-fiber minus ends and spindle poles, and promotes bipolar spindle assembly through NUMA1 deubiquitination. This is an experimentally supported ABRAXAS2 cellular role rather than a generic cell-cycle phenotype.
Supporting Evidence:
PMID:26195665
BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
PMID:26195665
promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
GO:0030496 midbody
IDA
PMID:26195665
The deubiquitinating enzyme complex BRISC is required for pr...
ACCEPT
Summary: midbody localization is supported by mitotic imaging.
Reason: ABRAXAS2/BRISC was observed at centrosomes, spindle poles, K-fiber minus ends, and midbody during mitosis [PMID:26195665].
Supporting Evidence:
PMID:26195665
ABRO1 was shown to be located at the centrosomes in interphase
PMID:26195665
BRISC localizes at centrosomes, spindle poles, and midbody during mitosis.
GO:0031616 spindle pole centrosome
IDA
PMID:26195665
The deubiquitinating enzyme complex BRISC is required for pr...
ACCEPT
Summary: spindle pole centrosome localization is supported by mitotic imaging.
Reason: ABRAXAS2/BRISC was observed at centrosomes, spindle poles, K-fiber minus ends, and midbody during mitosis [PMID:26195665].
Supporting Evidence:
PMID:26195665
ABRO1 was shown to be located at the centrosomes in interphase
PMID:26195665
BRISC localizes at centrosomes, spindle poles, and midbody during mitosis.
GO:0036449 microtubule minus-end
IDA
PMID:26195665
The deubiquitinating enzyme complex BRISC is required for pr...
ACCEPT
Summary: microtubule minus-end localization is supported by mitotic imaging.
Reason: ABRAXAS2/BRISC was observed at centrosomes, spindle poles, K-fiber minus ends, and midbody during mitosis [PMID:26195665].
Supporting Evidence:
PMID:26195665
ABRO1 was shown to be located at the centrosomes in interphase
PMID:26195665
BRISC localizes at centrosomes, spindle poles, and midbody during mitosis.
GO:0070536 protein K63-linked deubiquitination
IMP
PMID:24075985
A BRISC-SHMT complex deubiquitinates IFNAR1 and regulates in...
ACCEPT
Summary: Protein K63-linked deubiquitination is the central BRISC pathway function involving ABRAXAS2.
Reason: ABRAXAS2 is not the catalytic subunit, but it is a required scaffold/adaptor of BRISC, the BRCC36/BRCC3 K63-linked DUB complex. The cited studies support substrate-specific K63 deubiquitination of IFNAR1 or NUMA1 by ABRAXAS2-containing BRISC.
Supporting Evidence:
PMID:24075985
SHMT directs BRISC activity at K63-Ub chains conjugated to the type 1 interferon (IFN) receptor chain 1 (IFNAR1).
PMID:31142841
Direct interaction with SHMT2 enhances BRISC delivery to ubiquitylated type I interferon (IFN) receptors (IFNAR1/2)
GO:0070536 protein K63-linked deubiquitination
IMP
PMID:26195665
The deubiquitinating enzyme complex BRISC is required for pr...
ACCEPT
Summary: Protein K63-linked deubiquitination is the central BRISC pathway function involving ABRAXAS2.
Reason: ABRAXAS2 is not the catalytic subunit, but it is a required scaffold/adaptor of BRISC, the BRCC36/BRCC3 K63-linked DUB complex. The cited studies support substrate-specific K63 deubiquitination of IFNAR1 or NUMA1 by ABRAXAS2-containing BRISC.
Supporting Evidence:
PMID:26195665
BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
PMID:26195665
promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
GO:0070552 BRISC complex
IDA
PMID:24075985
A BRISC-SHMT complex deubiquitinates IFNAR1 and regulates in...
ACCEPT
Summary: ABRAXAS2 is a bona fide BRISC complex subunit.
Reason: Multiple biochemical, structural, UniProt, and ComplexPortal sources identify ABRAXAS2/ABRO1 as the BRISC-specific scaffold paired with BRCC36/BRCC3, BABAM1/MERIT40, and BABAM2/BRE. This is the safest PN-projected annotation and is already in GOA.
Supporting Evidence:
PMID:21282113
ABRO1 complex does not interact with BRCA1
PMID:31253574
in BRCA1-A, BRCC36 is supported by ABRAXAS (Wang et al., 2007), whereas in BRISC, it is paired with ABRO1
GO:0090307 mitotic spindle assembly
IMP
PMID:26195665
The deubiquitinating enzyme complex BRISC is required for pr...
ACCEPT
Summary: mitotic spindle assembly is supported by ABRAXAS2/BRISC localization to mitotic microtubule structures and functional spindle defects after BRISC depletion.
Reason: PMID:26195665 directly shows ABRAXAS2/BRISC binds microtubules, localizes to K-fiber minus ends and spindle poles, and promotes bipolar spindle assembly through NUMA1 deubiquitination. This is an experimentally supported ABRAXAS2 cellular role rather than a generic cell-cycle phenotype.
Supporting Evidence:
PMID:26195665
BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
PMID:26195665
promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
GO:0002931 response to ischemia
IMP
PMID:21195082
Regulation of Abro1/KIAA0157 during myocardial infarction an...
KEEP AS NON CORE
Summary: Response to ischemia is supported in a cardiac injury model but is context-specific.
Reason: ABRO1 protein increases after myocardial ischemia/reperfusion and knockdown exacerbates cardiomyocyte damage, supporting the annotation. This is a tissue/stress phenotype rather than the core molecular function of ABRAXAS2.
Supporting Evidence:
PMID:21195082
Reducing the Abro1 protein level exacerbated cellular damage and cell death of cardiomyocytes due to MI/R injury.
GO:0005737 cytoplasm
IDA
PMID:21195082
Regulation of Abro1/KIAA0157 during myocardial infarction an...
ACCEPT
Summary: Cytoplasmic localization is well supported.
Reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
Supporting Evidence:
PMID:20656690
KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
PMID:21282113
ABRO1 is mainly localized in the cytoplasm.
GO:0070552 BRISC complex
IDA
PMID:19214193
K63-specific deubiquitination by two JAMM/MPN+ complexes: BR...
ACCEPT
Summary: ABRAXAS2 is a bona fide BRISC complex subunit.
Reason: Multiple biochemical, structural, UniProt, and ComplexPortal sources identify ABRAXAS2/ABRO1 as the BRISC-specific scaffold paired with BRCC36/BRCC3, BABAM1/MERIT40, and BABAM2/BRE. This is the safest PN-projected annotation and is already in GOA.
Supporting Evidence:
PMID:21282113
ABRO1 complex does not interact with BRCA1
PMID:31253574
in BRCA1-A, BRCC36 is supported by ABRAXAS (Wang et al., 2007), whereas in BRISC, it is paired with ABRO1
GO:0031593 polyubiquitin modification-dependent protein binding
IDA
PMID:19261749
NBA1, a new player in the Brca1 A complex, is required for D...
MARK AS OVER ANNOTATED
Summary: Polyubiquitin-dependent binding is plausible for the BRCC36 complex family, but this PMID directly concerns BRCA1-A rather than ABRAXAS2-containing BRISC.
Reason: ABRAXAS2-containing BRISC is a K63-ubiquitin-directed DUB complex, but the cited paper supports polyubiquitin-chain binding in the BRCA1-A complex, not direct ABRAXAS2 binding. Later structural and functional studies support BRISC ubiquitin-chain processing and substrate targeting, so the biological context is related, but this IDA annotation overstates direct evidence for ABRAXAS2 as the enabling binder [PMID:19261749; PMID:31253574].
Supporting Evidence:
PMID:19261749
four members of the BRCA1-A complex possess a polyubiquitin chain-binding capability
GO:0060340 positive regulation of type I interferon-mediated signaling pathway
IMP
PMID:24075985
A BRISC-SHMT complex deubiquitinates IFNAR1 and regulates in...
NEW
Summary: NEW annotation: ABRAXAS2-containing BRISC promotes type I interferon signaling by deubiquitinating/stabilizing IFNAR1.
Reason: BRISC-SHMT targets K63-ubiquitinated IFNAR1, limits receptor internalization/degradation, and is required for full interferon responses. The GO term is more specific and better supported than a broad vitamin B6-response annotation.
Supporting Evidence:
PMID:24075985
SHMT directs BRISC activity at K63-Ub chains conjugated to the type 1 interferon (IFN) receptor chain 1 (IFNAR1).
PMID:31142841
Direct interaction with SHMT2 enhances BRISC delivery to ubiquitylated type I interferon (IFN) receptors (IFNAR1/2)
GO:0043517 positive regulation of DNA damage response, signal transduction by p53 class mediator
IMP
PMID:25283148
ABRO1 suppresses tumourigenesis and regulates the DNA damage...
NEW
Summary: NEW annotation: ABRAXAS2/ABRO1 positively regulates p53-mediated DNA-damage signaling.
Reason: The supported DNA-damage role is p53 stabilization and p53-dependent DNA-damage response, not direct DNA repair. This is why the PN-projected broad GO:0006281 DNA repair term is not proposed as a direct ABRAXAS2 annotation here.
Supporting Evidence:
PMID:25283148
ABRO1 stabilizes p53 by facilitating the interaction of p53 with USP7.
PMID:25283148
the induction of p53 by DNA damage is almost completely attenuated by ABRO1 depletion

Core Functions

ABRAXAS2 is the BRISC-specific MPN-domain scaffold/adaptor paired with BRCC3/BRCC36 in a K63-linked deubiquitinating complex. Its core role is not catalysis; instead, ABRAXAS2 organizes the BRISC assembly, helps determine cytoplasmic/nuclear targeting, and provides an interaction surface that distinguishes BRISC from ABRAXAS1-containing BRCA1-A. Through this complex, ABRAXAS2 supports K63-linked deubiquitination of substrates such as IFNAR1 and NUMA1, with NLRP3 inflammasome recruitment supported as an additional BRISC substrate-targeting context.

Supporting Evidence:
  • PMID:19214193
    the activity was intrinsic to PA700 and the Brcc36 isopeptidase complex (BRISC)
  • PMID:20656690
    KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
  • PMID:24075985
    SHMT directs BRISC activity at K63-Ub chains conjugated to the type 1 interferon (IFN) receptor chain 1 (IFNAR1).
  • PMID:31142841
    Direct interaction with SHMT2 enhances BRISC delivery to ubiquitylated type I interferon (IFN) receptors (IFNAR1/2)
  • PMID:21282113
    ABRO1 complex does not interact with BRCA1
  • PMID:31253574
    in BRCA1-A, BRCC36 is supported by ABRAXAS (Wang et al., 2007), whereas in BRISC, it is paired with ABRO1
  • Reactome:R-HSA-5691439
    FAM175B (ABRO1), another BRISC subunit, binds directly to NLRP3 leading to FAM175B-dependent recruitment of the BRISC complex

ABRAXAS2-containing BRISC binds mitotic microtubule structures, accumulates at K-fiber minus ends, spindle poles, centrosomes, and midbody, and promotes functional bipolar spindle assembly. Mechanistically, BRISC deubiquitinates K63-linked ubiquitin chains on NUMA1, influencing NUMA1 interactions needed for spindle-pole organization and kinetochore-microtubule attachment.

Supporting Evidence:
  • PMID:26195665
    BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
  • PMID:26195665
    promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
  • PMID:26195665
    ABRO1 was shown to be located at the centrosomes in interphase
  • PMID:26195665
    BRISC localizes at centrosomes, spindle poles, and midbody during mitosis.

A secondary, stress-responsive ABRAXAS2 activity is p53 pathway regulation. ABRO1/ABRAXAS2 can accumulate and translocate to the nucleus after DNA damage, promotes USP7-p53 interaction, and stabilizes p53, thereby supporting p53-mediated DNA-damage signaling. This supports a specific p53-pathway process annotation but does not justify broad direct DNA repair annotation.

Supporting Evidence:
  • PMID:25283148
    ABRO1 stabilizes p53 by facilitating the interaction of p53 with USP7.
  • PMID:25283148
    the induction of p53 by DNA damage is almost completely attenuated by ABRO1 depletion
  • PMID:25283148
    DNA-damage induced accumulation of endogenous ABRO1 as well as translocation of ABRO1 to the nucleus
  • PMID:22974638
    during cellular stress it enters the nucleus and co-localizes with ATF4

References

Annotation inferences using phylogenetic trees
  • PANTHER phylogenetic annotations propagate conserved ABRAXAS2/ABRO1 family localization, microtubule, ubiquitin-chain binding, and mitotic spindle terms.
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping
  • UniProt subcellular-location keyword mapping supports broad nucleus, cytoplasm, cytoskeleton, and spindle-pole cellular component annotations.
Gene Ontology annotation based on curation of immunofluorescence data
  • Human Protein Atlas immunofluorescence curation supports ABRAXAS2 cytosol localization.
K63-specific deubiquitination by two JAMM/MPN+ complexes: BRISC-associated Brcc36 and proteasomal Poh1.
  • Biochemical fractionation identifies BRISC as a Brcc36-containing K63-specific deubiquitinating complex.
    "the activity was intrinsic to PA700 and the Brcc36 isopeptidase complex (BRISC)"
NBA1, a new player in the Brca1 A complex, is required for DNA damage resistance and checkpoint control.
  • The BRCA1-A complex study supports polyubiquitin-chain binding by related complex components, but its direct evidence is for BRCA1-A/ABRAXAS1 rather than ABRAXAS2/BRISC.
    "four members of the BRCA1-A complex possess a polyubiquitin chain-binding capability"
Defining the human deubiquitinating enzyme interaction landscape.
  • Proteomic interactome mapping places ABRAXAS2 among DUB-associated interaction data but does not by itself define an informative GO molecular function beyond generic protein binding.
    "We identified 774 candidate interacting proteins associated with 75 Dubs."
The Lys63-specific deubiquitinating enzyme BRCC36 is regulated by two scaffold proteins localizing in different subcellular compartments.
  • KIAA0157/ABRAXAS2 is a cytosolic scaffold that activates BRCC36 in the BRISC complex and distinguishes BRISC from nuclear BRCA1-A.
    "KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm."
Regulation of Abro1/KIAA0157 during myocardial infarction and cell death reveals a novel cardioprotective mechanism for Lys63-specific deubiquitination.
  • ABRO1 is induced in myocardial ischemia/reperfusion and contributes to cardioprotection through K63-linked deubiquitination.
    "Reducing the Abro1 protein level exacerbated cellular damage and cell death of cardiomyocytes due to MI/R injury."
NBA1/MERIT40 and BRE interaction is required for the integrity of two distinct deubiquitinating enzyme BRCC36-containing complexes.
  • ABRO1-containing BRISC is mainly cytoplasmic, lacks the BRCA1-interacting motif, and does not interact with BRCA1.
    "Because it lacks the BRCA1-interacting motif, the ABRO1 complex does not interact with BRCA1."
ATF4 interacts with Abro1/KIAA0157 scaffold protein and participates in a cytoprotective pathway.
  • ABRO1 can enter the nucleus during cellular stress and interact with ATF4 in a cytoprotective pathway.
    "Abro1 is predominantly cytoplasmic, but during cellular stress it enters the nucleus and co-localizes with ATF4."
A BRISC-SHMT complex deubiquitinates IFNAR1 and regulates interferon responses.
  • SHMT2 targets BRISC to K63-ubiquitinated IFNAR1, promoting receptor deubiquitination and type I interferon responses.
    "SHMT directs BRISC activity at K63-Ub chains conjugated to the type 1 interferon (IFN) receptor chain 1 (IFNAR1)."
ABRO1 suppresses tumourigenesis and regulates the DNA damage response by stabilizing p53.
  • ABRO1 promotes p53 stability by facilitating USP7-p53 interaction and is induced/translocated after DNA damage.
    "ABRO1 stabilizes p53 by facilitating the interaction of p53 with USP7."
The deubiquitinating enzyme complex BRISC is required for proper mitotic spindle assembly in mammalian cells.
  • BRISC localizes to microtubule minus ends and spindle poles, binds microtubules, and promotes spindle assembly by deubiquitinating NUMA.
    "BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs"
Metabolic control of BRISC-SHMT2 assembly regulates immune signalling.
  • PLP-dependent SHMT2 oligomerization regulates BRISC-SHMT2 assembly and type I interferon signaling.
    "Mutations in BRISC that disrupt SHMT2 binding impair type I interferon signalling in response to inflammatory stimuli."
Structural Basis of BRCC36 Function in DNA Repair and Immune Regulation.
  • Structures distinguish ABRAXAS/BRCA1-A DNA-repair targeting from ABRO1/BRISC immune-stress signaling and SHMT2 regulation.
    "The BRCA1-A and BRISC complexes serve in DNA double-strand break repair and immune signaling"
A reference map of the human binary protein interactome.
  • Large-scale binary interactome data support generic interaction evidence but not a specific ABRAXAS2 molecular function.
    "A reference map of the human binary protein interactome."
Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.
  • Proteome-scale AP-MS interaction data support generic interaction evidence but not a specific ABRAXAS2 molecular function.
    "Dual proteome-scale networks reveal cell-specific remodeling of the human interactome."
Quantitative fragmentomics allow affinity mapping of interactomes.
  • Fragment-level interactome data support generic interaction evidence but not a specific ABRAXAS2 molecular function.
    "Quantitative fragmentomics allow affinity mapping of interactomes."
AI-guided pipeline for protein-protein interaction drug discovery identifies a SARS-CoV-2 inhibitor.
  • A preprint interactome/drug-discovery pipeline reports generic interaction evidence that is not an informative ABRAXAS2 GO function.
    "AI-guided pipeline for protein-protein interaction drug discovery identifies a SARS-CoV-2 inhibitor."
Reactome:R-HSA-5691439
BRISC complex deubiquitinates NLRP3
  • Reactome places ABRO1/FAM175B in cytosolic BRISC-mediated K63 deubiquitination of NLRP3.
    "FAM175B (ABRO1), another BRISC subunit, binds directly to NLRP3 leading to FAM175B-dependent recruitment of the BRISC complex"
file:human/ABRAXAS2/ABRAXAS2-notes.md
ABRAXAS2 review notes
  • Local notes summarize the Proteostasis Network projected context and the conservative decision not to propagate broad DNA repair from PN context alone.
file:human/ABRAXAS2/ABRAXAS2-deep-research-falcon.md
ABRAXAS2 Falcon deep research report
  • Falcon deep research produced a secondary synthesis for ABRAXAS2; it was used only as orientation because the primary curation decisions were checked against cached primary literature and project files.

Suggested Questions for Experts

Q: Does ABRAXAS2-containing BRISC directly participate in DNA repair, or is its DNA-damage role limited to p53 stabilization and stress-response signaling outside the BRCA1-A repair complex?

Q: Which ABRAXAS2/BRISC substrates besides IFNAR1, NLRP3, and NUMA1 are physiologically dominant in primary human tissues?

Q: Should BRISC-SHMT2 metabolite-sensitive regulation be represented in GO as interferon-signaling regulation rather than broad vitamin B6 response for each BRISC component?

Suggested Experiments

Experiment: Test ABRAXAS2 knockout and rescue with BRISC-assembly-defective and SHMT2-binding-defective ABRAXAS2 mutants in IFN-stimulated primary cells, measuring IFNAR1 K63 ubiquitination, receptor surface abundance, and STAT1 phosphorylation.

Experiment: Compare ABRAXAS2 and ABRAXAS1 recruitment after DNA double-strand breaks using live-cell imaging and chromatin fractionation, with BRCA1, RAP80, and p53/USP7 readouts, to separate direct DNA-repair targeting from p53-mediated DNA-damage signaling.

Experiment: Reconstitute purified human BRISC variants with NUMA1 fragments and K63-linked ubiquitin chains to test whether ABRAXAS2 microtubule-binding and scaffold regions control substrate selection during spindle assembly.

Deep Research

Falcon

(ABRAXAS2-deep-research-falcon.md)
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate. Falcon Edison Scientific Literature 16 citations 2 artifacts 2026-06-03T09:15:11.506141

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Comprehensive research report: Human ABRAXAS2 (ABRO1/FAM175B; UniProt Q15018)

0) Identity verification (critical disambiguation)

ABRAXAS2 (also widely referred to as ABRO1, FAM175B, and KIAA0157) encodes the BRISC complex subunit Abraxas 2 in Homo sapiens and belongs to the FAM175 (Abro1) family. In the ubiquitin-signaling literature, ABRAXAS2/ABRO1 is explicitly distinguished from its paralog ABRAXAS/FAM175A, which is the scaffold that defines the nuclear BRCA1-A complex; in contrast, ABRAXAS2/ABRO1 defines BRISC and mediates BRISC-specific interactions such as binding to SHMT2α. This distinction is consistently made in structural and review sources and is essential to avoid misannotation (https://doi.org/10.1016/j.molcel.2019.06.002, 2019-08; https://doi.org/10.3390/biom10111503, 2020-10) (julius2019structuralbasisof pages 10-12, julius2019structuralbasisof pages 1-3, julius2020brca1aandbrisc pages 1-3).

1) Key concepts and definitions (current understanding)

1.1 BRISC vs BRCA1-A: two BRCC36-containing JAMM DUB assemblies

The catalytically active deubiquitinase in both BRISC and BRCA1-A is BRCC36 (also termed BRCC3 in some literature), a JAMM/MPN+ metalloprotease-type DUB. Both assemblies share core subunits (BRCC36/BRCC3, BRE, MERIT40) but differ in their defining scaffold: BRISC uses ABRAXAS2/ABRO1, whereas BRCA1-A uses ABRAXAS (FAM175A) and includes RAP80, enabling BRCA1-A’s DNA damage response functions (https://doi.org/10.1016/j.molcel.2019.06.002, 2019-08; https://doi.org/10.3390/biom10111503, 2020-10) (julius2019structuralbasisof pages 1-3, julius2020brca1aandbrisc pages 11-13).

1.2 What ABRAXAS2 does (molecular role)

ABRAXAS2/ABRO1 is noncatalytic and functions as an MPN− scaffold/activator subunit. It is required for assembly-dependent activation of the catalytic subunit BRCC36: ABRO1 contributes a key scaffold residue (Asn164) that helps structure/position BRCC36’s catalytic elements (including the E-loop), enabling robust enzymatic activity in the assembled complex (https://doi.org/10.3390/biom10111503, 2020-10; https://doi.org/10.1016/j.molcel.2019.06.002, 2019-08) (julius2020brca1aandbrisc pages 8-11, julius2019structuralbasisof pages 3-4).

1.3 Enzymatic activity and substrate linkage specificity (what reaction is catalyzed)

ABRAXAS2 is not itself an enzyme; rather, it specifies and activates BRISC’s DUB activity. BRCC36/BRISC is described as strictly specific for Lys63-linked (K63) ubiquitin chains, i.e., it catalyzes the hydrolysis of isopeptide bonds in K63-linked polyubiquitin, preferentially cleaving longer chains (e.g., (Ub)4 and longer) in biochemical assays (https://doi.org/10.3390/biom10111503, 2020-10; https://doi.org/10.1016/j.molcel.2019.06.002, 2019-08) (julius2020brca1aandbrisc pages 8-11, julius2019structuralbasisof pages 3-4).

2) Complex membership, interactors, and structural/biochemical mechanism

2.1 Core complex composition

A structural study reports BRISC as an assembly that can include two copies each of BRCC36, ABRO1 (ABRAXAS2), BRE, MERIT40, and SHMT2α, providing direct experimental evidence of ABRAXAS2’s role as a BRISC core subunit and of BRISC–SHMT2 association (https://doi.org/10.1016/j.molcel.2019.06.002, 2019-08) (julius2019structuralbasisof pages 3-4). This architecture is visualized in the BRISC structure figure panels showing the domain organization and assembled complex (julius2019structuralbasisof media c51f4bbd, julius2019structuralbasisof media caaada58).

2.2 ABRAXAS2–SHMT2 interaction and metabolic regulation of BRISC

ABRAXAS2/ABRO1 confers a specific, high-affinity interaction between BRISC and the metabolic enzyme SHMT2α, which acts as a protein inhibitor of BRISC by sterically blocking the BRCC36 active site. The 2020 review summarizes that purified BRISC binds apo-SHMT2α with low-nanomolar affinity, and that PLP binding (favoring tetrameric SHMT2) can shift the equilibrium and relieve inhibition of BRISC DUB activity (https://doi.org/10.3390/biom10111503, 2020-10; https://doi.org/10.1016/j.molcel.2019.06.002, 2019-08) (julius2020brca1aandbrisc pages 8-11, julius2019structuralbasisof pages 10-12). The BRISC–SHMT2 interaction interface and inhibition mechanism is illustrated in figures focused on SHMT2 binding (julius2019structuralbasisof media c51f4bbd, julius2019structuralbasisof media caaada58).

2.3 Additional reported partners/substrate contexts

The review literature links BRISC (and thus ABRAXAS2) to deubiquitination contexts including IFNAR1 (type I interferon receptor chain 1), HIV-1 Tat, and JAK2 signaling, where ABRO1’s C-terminal tail contains a phosphotyrosine site (Y377) bound by the SH2 domain of LNK (https://doi.org/10.3390/biom10111503, 2020-10) (julius2020brca1aandbrisc pages 8-11, julius2020brca1aandbrisc pages 3-6).

3) Subcellular localization (where ABRAXAS2 functions)

BRISC is described as present in both nucleus and cytoplasm, whereas BRCA1-A is predominantly nuclear and functions at DNA damage sites (https://doi.org/10.1016/j.molcel.2019.06.002, 2019-08) (julius2019structuralbasisof pages 3-4, julius2019structuralbasisof pages 1-3). Quantitative immunofluorescence imaging in the 2019 structural study explicitly assessed endogenous ABRO1 (ABRAXAS2) and SHMT2 across nuclear, cytosolic, and mitochondria-associated pools, supporting multi-compartment localization relevant to SHMT2 biology (julius2019structuralbasisof media c51f4bbd).

4) Pathways and biological processes (functional annotation)

4.1 Innate immune signaling and receptor trafficking

A well-supported mechanistic substrate context summarized in the review is that BRISC deubiquitinates IFNAR1, which is described as limiting receptor endocytosis/internalization, thereby modulating type I interferon signaling outputs (https://doi.org/10.3390/biom10111503, 2020-10) (julius2020brca1aandbrisc pages 8-11).

4.2 Recent developments (prioritized 2023): NF-κB activation in Kupffer cells and acute liver injury

A 2023 study in Cell Death & Disease reports that ABRO1 (ABRAXAS2) is required for optimal activation of canonical NF-κB signaling in LPS-stimulated Kupffer cells (KCs) and that loss of ABRO1 or BRCC3/BRCC36 protects mice from D-GalN/LPS-induced acute liver injury (https://doi.org/10.1038/s41419-023-06268-z, 2023-11) (zhang2023briscisrequired pages 7-10, zhang2023briscisrequired pages 2-3).

Key mechanistic findings reported include:
- In Abro1−/− KCs, canonical NF-κB readouts are impaired (reduced IκBα phosphorylation/degradation and reduced p65 phosphorylation), while MAPK signaling (JNK/ERK1/2/p38) is not substantially affected (zhang2023briscisrequired pages 7-10).
- Abro1−/− KCs show reduced NF-κB functional outputs including NF-κB reporter activity, p65 nuclear translocation, and NF-κB DNA binding (zhang2023briscisrequired pages 7-10).

Quantitative in vivo inflammatory outputs include:
- At 1 hour after D-GalN/LPS challenge, serum TNF-α and hepatic TNF-α are decreased by 48.5% and 45.5%, respectively, in Abro1−/− mice (zhang2023briscisrequired pages 3-6).
- A lethal D-GalN/LPS dose caused 100% mortality in WT within 8 h, while >70% of Abro1−/− (and Brcc3−/−) mice survived long-term (zhang2023briscisrequired pages 2-3).

The study further reports reduced KC proinflammatory cytokine/chemokine production (including TNF-α, IL-6, IL-1β, MCP-1, and others) and identifies KCs as key effector cells via bone marrow chimera and cell-specific deletion approaches (zhang2023briscisrequired pages 6-7, zhang2023briscisrequired pages 3-6).

4.3 Inflammasome (NLRP3) context

The 2023 paper also notes BRISC involvement in IFNAR1 and NLRP3 inflammasome activation in hepatic macrophages, consistent with prior literature placing BRISC in innate immune regulation; in this context ABRO1 is described as recruiting BRISC to NLRP3 for deubiquitination to promote inflammasome activation (zhang2023briscisrequired pages 7-10, zhang2023briscisrequired pages 2-3).

5) Current applications and real-world implementations

5.1 Preclinical pharmacologic targeting of BRISC (proof-of-concept)

Zhang et al. (2023) report that thiolutin, described as a potent BRISC inhibitor in the study, markedly alleviated D-GalN/LPS-induced acute liver injury and improved survival; mechanistically, exogenous TNF-α (15 μg/kg) abolished thiolutin’s protective effect, supporting TNF-α suppression as a key component of the observed benefit (https://doi.org/10.1038/s41419-023-06268-z, 2023-11) (zhang2023briscisrequired pages 6-7).

This constitutes a concrete in vivo preclinical implementation of targeting the ABRAXAS2-containing BRISC axis to modulate macrophage-driven inflammation (zhang2023briscisrequired pages 6-7).

5.2 Disease association signals (genetics/omics aggregation)

Open Targets lists statistical associations between ABRAXAS2 and multiple disease terms (e.g., knee osteoarthritis and Alzheimer disease), with example overall association scores around 0.27–0.32 for the displayed diseases and linked literature evidence (PubMed IDs 39998322 and 40205036) (OpenTargets Search: -ABRAXAS2). These associations are hypothesis-generating and should be interpreted in the context of underlying evidence type and causality.

6) Expert synthesis and authoritative interpretations

An authoritative review frames BRCA1-A and BRISC as “multifunctional molecular machines” in ubiquitin signaling and emphasizes that their distinct biological roles arise largely from exchanging the MPN− scaffold subunit (ABRAXAS vs ABRO1/ABRAXAS2) while sharing the same catalytic core (BRCC36) and K63 chain specificity (https://doi.org/10.3390/biom10111503, 2020-10) (julius2020brca1aandbrisc pages 1-3). The structural primary study provides mechanistic support for this view by showing assembly-dependent activation and the ABRO1-conferred SHMT2 inhibitory module (https://doi.org/10.1016/j.molcel.2019.06.002, 2019-08) (julius2019structuralbasisof pages 3-4).

7) Recent developments (2023–2024) and evidence gaps

Within the documents retrievable via the current tool workflow, the major post-2022 mechanistic advance specific to ABRAXAS2/ABRO1 is the 2023 Kupffer-cell NF-κB / acute liver injury study (https://doi.org/10.1038/s41419-023-06268-z, 2023-11) (zhang2023briscisrequired pages 7-10, zhang2023briscisrequired pages 3-6). No ABRAXAS2-focused primary studies from 2024 were successfully retrieved by the available searches in this run; therefore, the 2024 portion of “latest research” could not be comprehensively covered here, and additional targeted retrieval (e.g., by PubMed IDs from Open Targets or by searching ABRO1-specific keywords in other indices) would likely be needed for full 2024 coverage.

8) Summary table of functional annotation

The following table consolidates key points (identity, complex membership, mechanism, localization, pathways, quantitative data, and translational angles) with publication years and DOI URLs.

Aspect ABRAXAS2-specific summary Evidence type Key quantitative data Year DOI / URL
Verified protein identity Human ABRAXAS2 encodes BRISC complex subunit Abraxas 2; common synonyms include ABRO1, FAM175B, and KIAA0157. It is the ABRAXAS paralog that defines BRISC, not BRCA1-A. Literature distinguishes ABRO1/ABRAXAS2 from ABRAXAS/FAM175A, the BRCA1-A scaffold subunit (julius2020brca1aandbrisc pages 8-11, julius2020brca1aandbrisc pages 3-6, julius2019structuralbasisof pages 1-3, julius2020brca1aandbrisc pages 1-3). Structural, review synthesis Protein length reported in review: 415 aa (julius2020brca1aandbrisc pages 3-6) 2019, 2020 https://doi.org/10.1016/j.molcel.2019.06.002 ; https://doi.org/10.3390/biom10111503
Complex membership ABRAXAS2/ABRO1 is a core scaffold subunit of BRISC together with BRCC36/BRCC3, BRE, and MERIT40; BRISC can assemble with SHMT2α. By contrast, BRCA1-A contains ABRAXAS (FAM175A) plus RAP80 and binds BRCA1, whereas BRISC contains ABRO1 and does not recruit BRCA1 in the same way (julius2020brca1aandbrisc pages 8-11, julius2019structuralbasisof pages 3-4, julius2019structuralbasisof pages 1-3, julius2020brca1aandbrisc pages 11-13, julius2020brca1aandbrisc pages 1-3). Structural, biochemical BRISC structure reported with two copies each of BRCC36, ABRO1, BRE, MERIT40, and SHMT2α (julius2019structuralbasisof pages 3-4) 2019, 2020 https://doi.org/10.1016/j.molcel.2019.06.002 ; https://doi.org/10.3390/biom10111503
Core interactors Key ABRAXAS2-associated proteins are BRCC36/BRCC3 (catalytic JAMM DUB), BRE, MERIT40, SHMT2α, and LNK; ABRO1 confers specific high-affinity SHMT2α binding to BRISC, while its C-terminal pY377 recruits LNK SH2 in JAK2 signaling contexts (julius2020brca1aandbrisc pages 8-11, julius2019structuralbasisof pages 10-12, julius2020brca1aandbrisc pages 3-6, julius2019structuralbasisof pages 23-25). Structural, biochemical SHMT2α binding described as low-nanomolar affinity (julius2020brca1aandbrisc pages 8-11) 2019, 2020 https://doi.org/10.1016/j.molcel.2019.06.002 ; https://doi.org/10.3390/biom10111503
Molecular function ABRAXAS2 is a noncatalytic MPN− scaffold/activator that enables assembly-dependent activation of the BRCC36 deubiquitinase. ABRO1 contributes Asn164 to position the BRCC36 catalytic machinery/E-loop, allowing BRCC36 activity within BRISC. BRCC36 is the catalytic enzyme; ABRAXAS2 functions as its structural activator/specifier (julius2020brca1aandbrisc pages 8-11, julius2020brca1aandbrisc pages 3-6, julius2019structuralbasisof pages 3-4). Structural, biochemical Assembly-dependent activation involves ABRO1 N164; BRCC36 is inactive alone and active in assembled complex (julius2020brca1aandbrisc pages 8-11, julius2019structuralbasisof pages 3-4) 2019, 2020 https://doi.org/10.1016/j.molcel.2019.06.002 ; https://doi.org/10.3390/biom10111503
Ubiquitin-chain specificity Through BRCC36, BRISC is strictly K63-linkage specific. ABRAXAS2 therefore functions in a complex that edits K63-linked polyubiquitin rather than catalyzing chemistry directly itself (julius2020brca1aandbrisc pages 8-11, julius2019structuralbasisof pages 1-3, julius2020brca1aandbrisc pages 1-3). Biochemical, structural BRCC36/BRISC described as strictly specific for K63-linked ubiquitin chains (julius2020brca1aandbrisc pages 8-11) 2019, 2020 https://doi.org/10.1016/j.molcel.2019.06.002 ; https://doi.org/10.3390/biom10111503
Chain-length preference Assembled BRISC shows preferential cleavage of longer K63 polyubiquitin chains, especially tetraubiquitin and above, consistent with avidity created by the arc-shaped multiprotein scaffold (julius2020brca1aandbrisc pages 8-11, julius2019structuralbasisof pages 3-4). Biochemical, structural Preferential cleavage of (Ub)4 and longer chains reported (julius2019structuralbasisof pages 3-4) 2019, 2020 https://doi.org/10.1016/j.molcel.2019.06.002 ; https://doi.org/10.3390/biom10111503
Regulation by SHMT2 and PLP ABRO1 mediates SHMT2α docking to BRISC, and bound apo-SHMT2α sterically blocks the BRCC36 active site, functioning as a protein inhibitor of BRISC. PLP promotes SHMT2 tetramerization, weakens BRISC association, and can release active BRISC (julius2020brca1aandbrisc pages 8-11, julius2019structuralbasisof pages 10-12). Structural, biochemical SHMT2α acts as a high-affinity/low-nanomolar BRISC inhibitor; PLP shifts SHMT2 equilibrium and regulates BRISC DUB activity (julius2020brca1aandbrisc pages 8-11) 2019, 2020 https://doi.org/10.1038/s41586-019-1232-1 ; https://doi.org/10.1016/j.molcel.2019.06.002 ; https://doi.org/10.3390/biom10111503
Subcellular localization BRISC containing ABRAXAS2 is reported in both nucleus and cytoplasm, unlike BRCA1-A which is predominantly nuclear. Quantitative imaging also examined mitochondrial association/colocalization of endogenous ABRO1 and SHMT2, supporting distribution across nucleus, cytosol, and mitochondria-associated pools (julius2019structuralbasisof pages 3-4, julius2019structuralbasisof pages 23-25, julius2019structuralbasisof media c51f4bbd). Structural, imaging Figure evidence indicates localization in nucleus, cytosol, and mitochondria (julius2019structuralbasisof media c51f4bbd) 2019 https://doi.org/10.1016/j.molcel.2019.06.002
Distinction from BRCA1-A ABRAXAS2 should not be confused with ABRAXAS/FAM175A. BRCA1-A uses ABRAXAS, recruits RAP80, and binds BRCA1 BRCT repeats; ABRAXAS2 instead functionalizes BRISC, especially via SHMT2 and immune/endosomal signaling. This distinction is central for correct annotation (julius2019structuralbasisof pages 10-12, julius2019structuralbasisof pages 1-3, julius2020brca1aandbrisc pages 11-13). Structural, biochemical In BRCA1-A, assembled complex binds BRCA1 BRCT with Kd ~80 nM via ABRAXAS phospho-tail, illustrating a paralog-specific property not attributed to ABRAXAS2 (julius2020brca1aandbrisc pages 11-13) 2019, 2020 https://doi.org/10.1016/j.molcel.2019.06.002 ; https://doi.org/10.3390/biom10111503
IFN signaling / receptor trafficking ABRAXAS2-containing BRISC promotes deubiquitination of IFNAR1, limiting receptor internalization/endocytosis and stabilizing type I interferon receptor signaling outputs. This is one of the clearest physiological substrate contexts for BRISC (julius2020brca1aandbrisc pages 8-11, zhang2023briscisrequired pages 2-3). Biochemical, cellular, genetic Qualitative mechanism: BRISC deubiquitinates IFNAR1 K63-Ub, limiting endocytosis (julius2020brca1aandbrisc pages 8-11) 2020, 2023 https://doi.org/10.3390/biom10111503 ; https://doi.org/10.1038/s41419-023-06268-z
Inflammasome / NLRP3 biology ABRAXAS2 has been implicated in recruiting BRISC to NLRP3, enabling deubiquitination of NLRP3 and promoting inflammasome activation. This places ABRAXAS2 in innate immune signaling beyond IFNAR1 regulation (zhang2023briscisrequired pages 7-10, zhang2023briscisrequired pages 2-3). Genetic, cellular, pathway analysis Reported qualitatively as promoting NLRP3-dependent IL-1β and IL-18 responses; no exact numeric effect size captured in available excerpts (zhang2023briscisrequired pages 2-3) 2023 https://doi.org/10.1038/s41419-023-06268-z
NF-κB in Kupffer cells / acute liver injury 2023 work shows ABRO1/ABRAXAS2 is required for optimal canonical NF-κB activation in LPS-stimulated Kupffer cells. Loss of ABRO1 impairs IκBα phosphorylation/degradation, p65 phosphorylation, p65 nuclear translocation, NF-κB reporter activity, and cytokine production, while MAPKs are largely unaffected (zhang2023briscisrequired pages 7-10, zhang2023briscisrequired pages 1-2, zhang2023briscisrequired pages 6-7, zhang2023briscisrequired pages 3-6, zhang2023briscisrequired pages 2-3). Genetic, cellular, in vivo mouse model Serum TNF-α reduced by 48.5% and hepatic TNF-α by 45.5% at 1 h post D-GalN/LPS in Abro1−/− mice; lethal challenge caused 100% WT mortality within 8 h versus >70% survival in Abro1−/− and Brcc3−/− mice (zhang2023briscisrequired pages 3-6, zhang2023briscisrequired pages 2-3) 2023 https://doi.org/10.1038/s41419-023-06268-z
Cytokine/chemokine outputs In ABRO1-deficient settings, TNF-α, IL-6, IL-1β, MCP-1, MIP-1α, and MIP-1β are reduced in serum, liver, or isolated Kupffer cells after inflammatory challenge, indicating ABRAXAS2 promotes early inflammatory cytokine amplification in liver macrophages (zhang2023briscisrequired pages 1-2, zhang2023briscisrequired pages 6-7, zhang2023briscisrequired pages 3-6). Genetic, flow cytometry, ELISA/CBA, RT-PCR LPS-induced cytokine reductions seen across 0.1 ng/mL to 1 μg/mL LPS in KCs; early cytokine defects evident 1 h after challenge (zhang2023briscisrequired pages 6-7, zhang2023briscisrequired pages 3-6) 2023 https://doi.org/10.1038/s41419-023-06268-z
Mitosis and other roles Reviews summarize ABRAXAS2/BRISC functions in mitosis (including NuMA ubiquitination), telomere-associated tankyrase regulation, hematopoiesis, and JAK2 signaling through LNK, extending its annotation beyond innate immunity (julius2020brca1aandbrisc pages 8-11, julius2020brca1aandbrisc pages 1-3). Review synthesis from primary studies Quantitative values not captured in available excerpts; roles supported by curated review of primary literature (julius2020brca1aandbrisc pages 8-11, julius2020brca1aandbrisc pages 1-3) 2020 https://doi.org/10.3390/biom10111503
Therapeutic relevance Pharmacologic BRISC inhibition is proposed as therapeutically useful in inflammatory disease. In the 2023 liver study, thiolutin (THL) markedly alleviated D-GalN/LPS-induced injury, and NF-κB activators rescued cytokine production in ABRO1-deficient Kupffer cells, functionally tying BRISC to this pathway (zhang2023briscisrequired pages 1-2, zhang2023briscisrequired pages 6-7). Pharmacologic, genetic THL increased survival, reduced ALT/AST, serum TNF-α/MCP-1, necrosis, and ex vivo KC cytokine release; exogenous TNF-α 15 μg/kg abolished THL protection (zhang2023briscisrequired pages 6-7) 2023 https://doi.org/10.1038/s41419-023-06268-z

Table: This table summarizes verified identity, complex membership, molecular mechanism, localization, signaling roles, and therapeutic relevance of human ABRAXAS2/ABRO1/FAM175B. It is useful for distinguishing ABRAXAS2 from the related BRCA1-A scaffold ABRAXAS and for tracing the strongest structural, biochemical, and genetic evidence.

9) Key references (URLs and publication dates)

  • Rabl J. BRCA1-A and BRISC: Multifunctional Molecular Machines for Ubiquitin Signaling. Biomolecules. 2020-10. https://doi.org/10.3390/biom10111503 (julius2020brca1aandbrisc pages 8-11, julius2020brca1aandbrisc pages 1-3)
  • Rabl J, et al. Structural Basis of BRCC36 Function in DNA Repair and Immune Regulation. Molecular Cell. 2019-08. https://doi.org/10.1016/j.molcel.2019.06.002 (julius2019structuralbasisof pages 3-4, julius2019structuralbasisof media c51f4bbd)
  • Zhang W, et al. BRISC is required for optimal activation of NF-κB in Kupffer cells induced by LPS and contributes to acute liver injury. Cell Death & Disease. 2023-11. https://doi.org/10.1038/s41419-023-06268-z (zhang2023briscisrequired pages 7-10, zhang2023briscisrequired pages 3-6)
  • Open Targets Platform: ABRAXAS2 disease associations (evidence-linked). Accessed via tool output. (OpenTargets Search: -ABRAXAS2)

References

  1. (julius2019structuralbasisof pages 10-12): Julius Rabl, Richard D. Bunker, Andreas D. Schenk, Simone Cavadini, Mark E. Gill, Wassim Abdulrahman, Amparo Andrés-Pons, Martijn S. Luijsterburg, Adel F. M. Ibrahim, Emma Branigan, Jacob D. Aguirre, Aimee H. Marceau, Claire Guérillon, Tewis Bouwmeester, Ulrich Hassiepen, Antoine H.F.M. Peters, Martin Renatus, Laurent Gelman, Seth M. Rubin, Niels Mailand, Haico van Attikum, Ronald T. Hay, and Nicolas H. Thomä. Structural basis of brcc36 function in dna repair and immune regulation. Molecular Cell, 75:483-497.e9, Aug 2019. URL: https://doi.org/10.1016/j.molcel.2019.06.002, doi:10.1016/j.molcel.2019.06.002. This article has 86 citations and is from a highest quality peer-reviewed journal.

  2. (julius2019structuralbasisof pages 1-3): Julius Rabl, Richard D. Bunker, Andreas D. Schenk, Simone Cavadini, Mark E. Gill, Wassim Abdulrahman, Amparo Andrés-Pons, Martijn S. Luijsterburg, Adel F. M. Ibrahim, Emma Branigan, Jacob D. Aguirre, Aimee H. Marceau, Claire Guérillon, Tewis Bouwmeester, Ulrich Hassiepen, Antoine H.F.M. Peters, Martin Renatus, Laurent Gelman, Seth M. Rubin, Niels Mailand, Haico van Attikum, Ronald T. Hay, and Nicolas H. Thomä. Structural basis of brcc36 function in dna repair and immune regulation. Molecular Cell, 75:483-497.e9, Aug 2019. URL: https://doi.org/10.1016/j.molcel.2019.06.002, doi:10.1016/j.molcel.2019.06.002. This article has 86 citations and is from a highest quality peer-reviewed journal.

  3. (julius2020brca1aandbrisc pages 1-3): Julius Rabl. Brca1-a and brisc: multifunctional molecular machines for ubiquitin signaling. Biomolecules, Oct 2020. URL: https://doi.org/10.3390/biom10111503, doi:10.3390/biom10111503. This article has 33 citations.

  4. (julius2020brca1aandbrisc pages 11-13): Julius Rabl. Brca1-a and brisc: multifunctional molecular machines for ubiquitin signaling. Biomolecules, Oct 2020. URL: https://doi.org/10.3390/biom10111503, doi:10.3390/biom10111503. This article has 33 citations.

  5. (julius2020brca1aandbrisc pages 8-11): Julius Rabl. Brca1-a and brisc: multifunctional molecular machines for ubiquitin signaling. Biomolecules, Oct 2020. URL: https://doi.org/10.3390/biom10111503, doi:10.3390/biom10111503. This article has 33 citations.

  6. (julius2019structuralbasisof pages 3-4): Julius Rabl, Richard D. Bunker, Andreas D. Schenk, Simone Cavadini, Mark E. Gill, Wassim Abdulrahman, Amparo Andrés-Pons, Martijn S. Luijsterburg, Adel F. M. Ibrahim, Emma Branigan, Jacob D. Aguirre, Aimee H. Marceau, Claire Guérillon, Tewis Bouwmeester, Ulrich Hassiepen, Antoine H.F.M. Peters, Martin Renatus, Laurent Gelman, Seth M. Rubin, Niels Mailand, Haico van Attikum, Ronald T. Hay, and Nicolas H. Thomä. Structural basis of brcc36 function in dna repair and immune regulation. Molecular Cell, 75:483-497.e9, Aug 2019. URL: https://doi.org/10.1016/j.molcel.2019.06.002, doi:10.1016/j.molcel.2019.06.002. This article has 86 citations and is from a highest quality peer-reviewed journal.

  7. (julius2019structuralbasisof media c51f4bbd): Julius Rabl, Richard D. Bunker, Andreas D. Schenk, Simone Cavadini, Mark E. Gill, Wassim Abdulrahman, Amparo Andrés-Pons, Martijn S. Luijsterburg, Adel F. M. Ibrahim, Emma Branigan, Jacob D. Aguirre, Aimee H. Marceau, Claire Guérillon, Tewis Bouwmeester, Ulrich Hassiepen, Antoine H.F.M. Peters, Martin Renatus, Laurent Gelman, Seth M. Rubin, Niels Mailand, Haico van Attikum, Ronald T. Hay, and Nicolas H. Thomä. Structural basis of brcc36 function in dna repair and immune regulation. Molecular Cell, 75:483-497.e9, Aug 2019. URL: https://doi.org/10.1016/j.molcel.2019.06.002, doi:10.1016/j.molcel.2019.06.002. This article has 86 citations and is from a highest quality peer-reviewed journal.

  8. (julius2019structuralbasisof media caaada58): Julius Rabl, Richard D. Bunker, Andreas D. Schenk, Simone Cavadini, Mark E. Gill, Wassim Abdulrahman, Amparo Andrés-Pons, Martijn S. Luijsterburg, Adel F. M. Ibrahim, Emma Branigan, Jacob D. Aguirre, Aimee H. Marceau, Claire Guérillon, Tewis Bouwmeester, Ulrich Hassiepen, Antoine H.F.M. Peters, Martin Renatus, Laurent Gelman, Seth M. Rubin, Niels Mailand, Haico van Attikum, Ronald T. Hay, and Nicolas H. Thomä. Structural basis of brcc36 function in dna repair and immune regulation. Molecular Cell, 75:483-497.e9, Aug 2019. URL: https://doi.org/10.1016/j.molcel.2019.06.002, doi:10.1016/j.molcel.2019.06.002. This article has 86 citations and is from a highest quality peer-reviewed journal.

  9. (julius2020brca1aandbrisc pages 3-6): Julius Rabl. Brca1-a and brisc: multifunctional molecular machines for ubiquitin signaling. Biomolecules, Oct 2020. URL: https://doi.org/10.3390/biom10111503, doi:10.3390/biom10111503. This article has 33 citations.

  10. (zhang2023briscisrequired pages 7-10): Wen Zhang, Kai Liu, Guang-Ming Ren, Yu Wang, Ting Wang, Xian Liu, Dong-Xu Li, Yang Xiao, Xu Chen, Ya-Ting Li, Yi-Qun Zhan, Shen-Si Xiang, Hui Chen, Hui-Ying Gao, Ke Zhao, Miao Yu, Chang-Hui Ge, Chang-Yan Li, Zhi-Qiang Ge, Xiao-Ming Yang, and Rong-Hua Yin. Brisc is required for optimal activation of nf-κb in kupffer cells induced by lps and contributes to acute liver injury. Cell Death & Disease, Nov 2023. URL: https://doi.org/10.1038/s41419-023-06268-z, doi:10.1038/s41419-023-06268-z. This article has 40 citations and is from a peer-reviewed journal.

  11. (zhang2023briscisrequired pages 2-3): Wen Zhang, Kai Liu, Guang-Ming Ren, Yu Wang, Ting Wang, Xian Liu, Dong-Xu Li, Yang Xiao, Xu Chen, Ya-Ting Li, Yi-Qun Zhan, Shen-Si Xiang, Hui Chen, Hui-Ying Gao, Ke Zhao, Miao Yu, Chang-Hui Ge, Chang-Yan Li, Zhi-Qiang Ge, Xiao-Ming Yang, and Rong-Hua Yin. Brisc is required for optimal activation of nf-κb in kupffer cells induced by lps and contributes to acute liver injury. Cell Death & Disease, Nov 2023. URL: https://doi.org/10.1038/s41419-023-06268-z, doi:10.1038/s41419-023-06268-z. This article has 40 citations and is from a peer-reviewed journal.

  12. (zhang2023briscisrequired pages 3-6): Wen Zhang, Kai Liu, Guang-Ming Ren, Yu Wang, Ting Wang, Xian Liu, Dong-Xu Li, Yang Xiao, Xu Chen, Ya-Ting Li, Yi-Qun Zhan, Shen-Si Xiang, Hui Chen, Hui-Ying Gao, Ke Zhao, Miao Yu, Chang-Hui Ge, Chang-Yan Li, Zhi-Qiang Ge, Xiao-Ming Yang, and Rong-Hua Yin. Brisc is required for optimal activation of nf-κb in kupffer cells induced by lps and contributes to acute liver injury. Cell Death & Disease, Nov 2023. URL: https://doi.org/10.1038/s41419-023-06268-z, doi:10.1038/s41419-023-06268-z. This article has 40 citations and is from a peer-reviewed journal.

  13. (zhang2023briscisrequired pages 6-7): Wen Zhang, Kai Liu, Guang-Ming Ren, Yu Wang, Ting Wang, Xian Liu, Dong-Xu Li, Yang Xiao, Xu Chen, Ya-Ting Li, Yi-Qun Zhan, Shen-Si Xiang, Hui Chen, Hui-Ying Gao, Ke Zhao, Miao Yu, Chang-Hui Ge, Chang-Yan Li, Zhi-Qiang Ge, Xiao-Ming Yang, and Rong-Hua Yin. Brisc is required for optimal activation of nf-κb in kupffer cells induced by lps and contributes to acute liver injury. Cell Death & Disease, Nov 2023. URL: https://doi.org/10.1038/s41419-023-06268-z, doi:10.1038/s41419-023-06268-z. This article has 40 citations and is from a peer-reviewed journal.

  14. (OpenTargets Search: -ABRAXAS2): Open Targets Query (-ABRAXAS2, 5 results). Buniello, A. et al. (2025). Open Targets Platform: facilitating therapeutic hypotheses building in drug discovery. Nucleic Acids Research.

  15. (julius2019structuralbasisof pages 23-25): Julius Rabl, Richard D. Bunker, Andreas D. Schenk, Simone Cavadini, Mark E. Gill, Wassim Abdulrahman, Amparo Andrés-Pons, Martijn S. Luijsterburg, Adel F. M. Ibrahim, Emma Branigan, Jacob D. Aguirre, Aimee H. Marceau, Claire Guérillon, Tewis Bouwmeester, Ulrich Hassiepen, Antoine H.F.M. Peters, Martin Renatus, Laurent Gelman, Seth M. Rubin, Niels Mailand, Haico van Attikum, Ronald T. Hay, and Nicolas H. Thomä. Structural basis of brcc36 function in dna repair and immune regulation. Molecular Cell, 75:483-497.e9, Aug 2019. URL: https://doi.org/10.1016/j.molcel.2019.06.002, doi:10.1016/j.molcel.2019.06.002. This article has 86 citations and is from a highest quality peer-reviewed journal.

  16. (zhang2023briscisrequired pages 1-2): Wen Zhang, Kai Liu, Guang-Ming Ren, Yu Wang, Ting Wang, Xian Liu, Dong-Xu Li, Yang Xiao, Xu Chen, Ya-Ting Li, Yi-Qun Zhan, Shen-Si Xiang, Hui Chen, Hui-Ying Gao, Ke Zhao, Miao Yu, Chang-Hui Ge, Chang-Yan Li, Zhi-Qiang Ge, Xiao-Ming Yang, and Rong-Hua Yin. Brisc is required for optimal activation of nf-κb in kupffer cells induced by lps and contributes to acute liver injury. Cell Death & Disease, Nov 2023. URL: https://doi.org/10.1038/s41419-023-06268-z, doi:10.1038/s41419-023-06268-z. This article has 40 citations and is from a peer-reviewed journal.

Artifacts

Citations

  1. julius2019structuralbasisof pages 3-4
  2. zhang2023briscisrequired pages 7-10
  3. zhang2023briscisrequired pages 3-6
  4. zhang2023briscisrequired pages 2-3
  5. zhang2023briscisrequired pages 6-7
  6. julius2019structuralbasisof pages 10-12
  7. julius2019structuralbasisof pages 1-3
  8. julius2019structuralbasisof pages 23-25
  9. zhang2023briscisrequired pages 1-2
  10. https://doi.org/10.1016/j.molcel.2019.06.002,
  11. https://doi.org/10.3390/biom10111503,
  12. https://doi.org/10.1038/s41419-023-06268-z,
  13. https://doi.org/10.1016/j.molcel.2019.06.002
  14. https://doi.org/10.3390/biom10111503
  15. https://doi.org/10.1038/s41586-019-1232-1
  16. https://doi.org/10.1038/s41419-023-06268-z

📚 Additional Documentation

Notes

(ABRAXAS2-notes.md)

ABRAXAS2 notes

Review setup

  • Ran just fetch-gene human ABRAXAS2, which created the UniProt, GOA, review stub, PANTHER family, Reactome, and cached publication files used here.
  • Ran just deep-research-falcon human ABRAXAS2 --fallback perplexity-lite. Falcon produced ABRAXAS2-deep-research-falcon.md with 16 citations and artifacts, but the recipe exited through its timeout path after 600 seconds. The configured fallback then failed with a Perplexity quota/auth error. I treated the Falcon file as secondary synthesis and based curation decisions on the fetched primary literature, UniProt, GOA, Reactome, and PN projection files.

Identity and complex context

  • ABRAXAS2 is the same protein as ABRO1/FAM175B/KIAA0157 and is the ABRAXAS paralog in BRISC rather than the BRCA1-A scaffold. PMID:21282113 distinguishes the complexes: ABRO1 is mainly cytoplasmic and "the ABRO1 complex does not interact with BRCA1" PMID:21282113. This is central for avoiding over-propagation from ABRAXAS1/BRCA1-A DNA-repair annotations.
  • BRISC is a K63-linked deubiquitinating complex; ABRAXAS2 is a noncatalytic scaffold/adaptor rather than the catalytic JAMM subunit. PMID:20656690 supports ABRAXAS2/KIAA0157 as a cytosolic scaffold that activates BRCC36 PMID:20656690.
  • Structural work separates ABRAXAS/BRCA1-A DNA-repair targeting from ABRO1/BRISC immune signaling and SHMT2 regulation PMID:31253574.

Proteostasis PN projection review

  • The PN projection file contains two ABRAXAS2 projections. GO:0070552 BRISC complex is already exact in GOA and is the safe propagation target for the noncatalytic BRISC subgroup [file:projects/PROTEOSTASIS/reports/pn_projection/pn_projected_gene_go_summary.tsv "ABRAXAS2 GO:0070552 BRISC complex already_in_goa_exact"].
  • The same projection file proposes new broad GO:0006281 DNA repair from a context group containing ABRAXAS1, ABRAXAS2, BABAM2, GCNA, and POLH [file:projects/PROTEOSTASIS/reports/pn_projection/pn_projected_gene_go_summary.tsv "ABRAXAS2 GO:0006281 DNA repair new_to_goa"]. I did not add this as a direct ABRAXAS2 annotation because the ABRAXAS2-specific literature supports BRISC scaffold, IFNAR1/NLRP3 signaling, spindle assembly, and p53-mediated damage-response signaling, not direct recruitment to DNA repair sites as in ABRAXAS1/BRCA1-A.
  • The conservative replacement for the DNA-damage evidence is GO:0043517 positive regulation of DNA damage response, signal transduction by p53 class mediator, based on ABRO1 stabilizing p53 and supporting DNA-damage-induced p53 accumulation PMID:25283148.

Major supported functions

  • BRISC scaffold/adaptor and K63-linked deubiquitination context: PMID:19214193 identifies BRISC as a K63-specific BRCC36-containing deubiquitinating complex PMID:19214193. ABRAXAS2 supports the complex but should not be annotated as the catalytic DUB subunit.
  • Type I interferon signaling is a strong process-level annotation. BRISC-SHMT targets K63-ubiquitinated IFNAR1 and limits receptor internalization/degradation PMID:24075985. The vitamin B6/PLP relationship is better represented as regulation of BRISC-SHMT2 assembly and interferon signaling, not as a direct broad response-to-vitamin-B6 function PMID:31142841.
  • Mitotic spindle assembly is directly supported. BRISC localizes to spindle poles/K-fiber minus ends, binds microtubules, and deubiquitinates NUMA1 to promote bipolar spindle assembly PMID:26195665 PMID:26195665.
  • Reactome places FAM175B/ABRO1 in BRISC-mediated NLRP3 deubiquitination, which supports BRISC innate immune context but does not require a new direct GO term beyond the current review scope [Reactome:R-HSA-5691439 "FAM175B (ABRO1), another BRISC subunit, binds directly to NLRP3 leading to FAM175B-dependent recruitment of the BRISC complex"].

Annotation decisions to watch

  • Generic GO:0005515 protein binding annotations from interactome or fragmentomics screens were removed as uninformative. More specific BRISC complex, K63-linked deubiquitination context, microtubule binding, and pathway terms capture the biology better.
  • GO:0031593 polyubiquitin modification-dependent protein binding was marked over-annotated for ABRAXAS2 itself. The biology is related to BRISC K63-ubiquitin processing, but ABRAXAS2 is a noncatalytic scaffold/adaptor and the PMID:19261749 IDA instance supports BRCA1-A/ABRAXAS1 complex polyubiquitin binding rather than direct ABRAXAS2/BRISC binding PMID:19261749.
  • GO:0005856 cytoskeleton was modified to microtubule/spindle-specific component terms because the direct evidence is centered on spindle poles, centrosomes, microtubule minus ends, and midbody.
  • GO:0000278 mitotic cell cycle was modified to the more specific spindle assembly, kinetochore-microtubule attachment, and chromosome segregation terms supported by PMID:26195665.

Pn Notes

(ABRAXAS2-pn-notes.md)

ABRAXAS2 PN Consistency Notes

  • Generated: 2026-06-18
  • Project: PROTEOSTASIS
  • Scope: PN consistency rereview against local AIGR review and available deep-research artifacts
  • UniProt: Q15018
  • AIGR review status: COMPLETE
  • Review batch: proteostasis-batch-2026-06-03 (PR 1329)
  • Batch change status: added

Source Files Checked

Deep Research Files

AIGR Review Snapshot

  • Description: ABRAXAS2 encodes Abraxas 2/ABRO1, a noncatalytic MPN-domain scaffold subunit of the BRISC K63-linked deubiquitinating complex. Together with BRCC3/BRCC36, BABAM1/MERIT40, and BABAM2/BRE, ABRAXAS2 helps assemble and localize BRISC in the cytoplasm and nucleus, where the complex removes K63-linked ubiquitin chains from substrates involved in immune receptor signaling and mitotic spindle organization. ABRAXAS2 also provides the BRISC-specific interface for SHMT2-dependent regulation and targeting, and it can translocate to the nucleus during cellular stress to influence p53-dependent DNA-damage signaling. Unlike ABRAXAS1, ABRAXAS2 lacks the BRCA1-interacting C-terminal phospho-motif and is not a canonical BRCA1-A DNA-repair adaptor.
  • Existing/core annotation action counts: ACCEPT: 35; KEEP_AS_NON_CORE: 1; MARK_AS_OVER_ANNOTATED: 2; MODIFY: 3; NEW: 2; REMOVE: 6

PN Consistency Summary

  • Consistency: Deep-research notes, review YAML, and PN-node BRISC mapping all agree ABRAXAS2 (=ABRO1/FAM175B) is a noncatalytic BRISC scaffold/adaptor, not a catalytic JAMM DUB. Partial contradiction at the DNA-repair node: the PN row-2 group projects broad GO:0006281 DNA repair, but the review and notes explicitly argue ABRO1 lacks the BRCA1-interacting motif and does NOT join BRCA1-A/DNA-repair sites (PMID:21282113), so direct DNA-repair propagation is rejected.
  • PN story / NEW pressure: BRISC complex membership is already captured (GO:0070552, IDA/IPI/NAS in GOA). The DNA-repair claim over-reaches for this paralog. The review instead adds well-supported NEW terms the PN node does not surface: GO:0043517 positive regulation of DNA damage response, signal transduction by p53 class mediator (OLS-verified real; PMID:25283148, ABRO1 stabilizes p53 via USP7) and GO:0060340 positive regulation of type I interferon-mediated signaling (PMID:24075985/31142841, BRISC-SHMT2/IFNAR1), plus NuMA spindle-assembly terms. Conclusion: BRISC = already captured; DNA repair = PN over-reaches; p53-DDR signaling = legitimate ADD already done in review.
  • Evidence alignment: PN row references (PMID:36473924, 19261749) overlap the review's BRISC/polyubiquitin-binding evidence (PMID:19261749 used, marked over-annotated as BRCA1-A-specific). Review extends far beyond PN refs (PMID:21282113, 20656690, 24075985, 25283148, 26195665, 31142841, 31253574) — divergence is enrichment, not conflict.
  • Verdict: Consistent on BRISC; PN DNA-repair projection over-reaches and is correctly declined; review's p53-DDR/IFN NEW terms are sound. Recommended edits: [MAP] Do not project GO:0006281 DNA repair to ABRAXAS2; the supported DNA-damage role is GO:0043517 (p53-class DDR signaling), already added in the review.

Full Consistency Review

  • UniProt: Q15018 · batch: proteostasis-batch-2026-06-03 · review status: COMPLETE
  • PN placement: Ubiquitin Proteasome System|DUBs and UBL demodifiers|BRISC complex|noncatalytic|JAMM / MPN / ubiquitin binding (row 1) and ...|Ubiquitin and UBL binding|DNA repair|BRISC complex component|... (row 2) ; PN-node mapping: group/type BRISC complex=mapped→GO:0070552 BRISC complex (already_in_goa_exact); group ...|DNA repair=mapped→GO:0006281 DNA repair (new_to_goa); class Ubiquitin and UBL binding=context_only (too_broad).
  • Consistency: Deep-research notes, review YAML, and PN-node BRISC mapping all agree ABRAXAS2 (=ABRO1/FAM175B) is a noncatalytic BRISC scaffold/adaptor, not a catalytic JAMM DUB. Partial contradiction at the DNA-repair node: the PN row-2 group projects broad GO:0006281 DNA repair, but the review and notes explicitly argue ABRO1 lacks the BRCA1-interacting motif and does NOT join BRCA1-A/DNA-repair sites (PMID:21282113), so direct DNA-repair propagation is rejected.
  • PN story / NEW pressure: BRISC complex membership is already captured (GO:0070552, IDA/IPI/NAS in GOA). The DNA-repair claim over-reaches for this paralog. The review instead adds well-supported NEW terms the PN node does not surface: GO:0043517 positive regulation of DNA damage response, signal transduction by p53 class mediator (OLS-verified real; PMID:25283148, ABRO1 stabilizes p53 via USP7) and GO:0060340 positive regulation of type I interferon-mediated signaling (PMID:24075985/31142841, BRISC-SHMT2/IFNAR1), plus NuMA spindle-assembly terms. Conclusion: BRISC = already captured; DNA repair = PN over-reaches; p53-DDR signaling = legitimate ADD already done in review.
  • Mapping strategy: The BRISC node mapping is correct and stable. The ...|DNA repair group node should not propagate GO:0006281 to ABRAXAS2 — the p53-class mediator is a paralog-specific signaling role, not direct repair. This mirrors the precedent of suppressing an over-broad projected term for a specific gene.
  • Evidence alignment: PN row references (PMID:36473924, 19261749) overlap the review's BRISC/polyubiquitin-binding evidence (PMID:19261749 used, marked over-annotated as BRCA1-A-specific). Review extends far beyond PN refs (PMID:21282113, 20656690, 24075985, 25283148, 26195665, 31142841, 31253574) — divergence is enrichment, not conflict.
  • Verdict: Consistent on BRISC; PN DNA-repair projection over-reaches and is correctly declined; review's p53-DDR/IFN NEW terms are sound. Recommended edits: [MAP] Do not project GO:0006281 DNA repair to ABRAXAS2; the supported DNA-damage role is GO:0043517 (p53-class DDR signaling), already added in the review.

PN Dossier Context

  • review_batch: proteostasis-batch-2026-06-03
  • review_yaml: genes/human/ABRAXAS2/ABRAXAS2-ai-review.yaml
  • PN workbook rows: 2

PN row 1: Ubiquitin Proteasome System | DUBs and UBL demodifiers | BRISC complex | noncatalytic | JAMM / MPN / ubiquitin binding

  • UniProt: Q15018
  • In branches: UPS
  • Signature domains: (none)
  • Auxiliary domains: IPR037518
  • PN references (titles):
    • 36473924
  • PN-node mapping records (path + ancestors):
    • [subtype] Ubiquitin Proteasome System|DUBs and UBL demodifiers|BRISC complex|noncatalytic|JAMM / MPN / ubiquitin binding
      status=no_mapping scope= GO=[]
      rationale: Reviewed manually as a UPS source node. No single GO term is appropriate for direct propagation from this PN label without narrower context or gene-level evidence.
    • [type] Ubiquitin Proteasome System|DUBs and UBL demodifiers|BRISC complex|noncatalytic
      status=mapped scope=ok_for_propagation_to_go GO=[GO:0070552 BRISC complex]
      rationale: This PN type covers noncatalytic BRISC subunits, so complex membership is the safe propagation target rather than catalytic DUB activity.
    • [group] Ubiquitin Proteasome System|DUBs and UBL demodifiers|BRISC complex
      status=mapped scope=ok_for_propagation_to_go GO=[GO:0070552 BRISC complex]
      rationale: This PN group denotes BRISC complex members. The matching GO cellular-component term is BRISC complex.
    • [class] Ubiquitin Proteasome System|DUBs and UBL demodifiers
      status=no_mapping scope= GO=[]
      rationale: Reviewed as a UPS taxonomy container. Its descendants mix catalytic roles, complex membership, binding domains, regulators, adaptors, and substrate-context labels, so a single propagating GO assertion would overstate the shared biology.
    • [branch] Ubiquitin Proteasome System
      status=no_mapping scope= GO=[]
      rationale: Reviewed as the top-level UPS branch. It is a project taxonomy umbrella rather than a direct GO assertion; UPS propagation must come from manually curated child nodes.

PN row 2: Ubiquitin Proteasome System | Ubiquitin and UBL binding | DNA repair | BRISC complex component | idiosyncratic Ub binding / MPN

  • UniProt: Q15018
  • In branches: UPS
  • Signature domains: PMID: 19261749 (IPR037518)
  • Auxiliary domains: (none)
  • PN references (titles):
    • 19261749
  • PN-node mapping records (path + ancestors):
    • [subtype] Ubiquitin Proteasome System|Ubiquitin and UBL binding|DNA repair|BRISC complex component|idiosyncratic Ub binding / MPN
      status=no_mapping scope= GO=[]
      rationale: Reviewed as a family, domain, architecture, or residual subdivision. The label is useful for PN taxonomy navigation but is not itself a GO annotation target; any functional assertion should come from a curated parent role or gene-level evidence.
    • [type] Ubiquitin Proteasome System|Ubiquitin and UBL binding|DNA repair|BRISC complex component
      status=no_mapping scope= GO=[]
      rationale: Reviewed as a UPS taxonomy container. Its descendants mix catalytic roles, complex membership, binding domains, regulators, adaptors, and substrate-context labels, so a single propagating GO assertion would overstate the shared biology.
    • [group] Ubiquitin Proteasome System|Ubiquitin and UBL binding|DNA repair
      status=mapped scope=ok_for_propagation_to_go GO=[GO:0006281 DNA repair]
      rationale: This PN group captures ubiquitin/UBL-binding factors assigned to DNA repair contexts. The group is context-defined rather than GO-equivalent, but propagation to DNA repair is appropriate.
    • [class] Ubiquitin Proteasome System|Ubiquitin and UBL binding
      status=context_only scope=too_broad_to_propagate GO=[GO:0140036 ubiquitin-modified protein reader activity]
      rationale: This class records ubiquitin/UBL-reader context, but the subtree mixes ubiquitin, SUMO, UBL-domain, domain-architecture, catalytic, signaling, trafficking, and nucleic-acid process buckets. It is useful context, not a safe direct propagation.
    • [branch] Ubiquitin Proteasome System
      status=no_mapping scope= GO=[]
      rationale: Reviewed as the top-level UPS branch. It is a project taxonomy umbrella rather than a direct GO assertion; UPS propagation must come from manually curated child nodes.

Projected GO annotations (3)

  • GO:0070552 BRISC complex | scope=ok_for_propagation_to_go | goa_status=already_in_goa_exact | from=Ubiquitin Proteasome System|DUBs and UBL demodifiers|BRISC complex
  • GO:0070552 BRISC complex | scope=ok_for_propagation_to_go | goa_status=already_in_goa_exact | from=Ubiquitin Proteasome System|DUBs and UBL demodifiers|BRISC complex|noncatalytic
  • GO:0006281 DNA repair | scope=ok_for_propagation_to_go | goa_status=new_to_goa | from=Ubiquitin Proteasome System|Ubiquitin and UBL binding|DNA repair

Note

This file is generated from the current PROTEOSTASIS phase-1 dossier and local gene-review artifacts. Edit the source review, PN mapping, or dossier rather than this generated note when correcting the underlying curation.

📄 View Raw YAML

id: Q15018
gene_symbol: ABRAXAS2
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: ABRAXAS2 encodes Abraxas 2/ABRO1, a noncatalytic MPN-domain scaffold subunit of the BRISC K63-linked deubiquitinating complex. Together with BRCC3/BRCC36, BABAM1/MERIT40, and BABAM2/BRE, ABRAXAS2 helps assemble and localize BRISC in the cytoplasm and nucleus, where the complex removes K63-linked ubiquitin chains from substrates involved in immune receptor signaling and mitotic spindle organization. ABRAXAS2 also provides the BRISC-specific interface for SHMT2-dependent regulation and targeting, and it can translocate to the nucleus during cellular stress to influence p53-dependent DNA-damage signaling. Unlike ABRAXAS1, ABRAXAS2 lacks the BRCA1-interacting C-terminal phospho-motif and is not a canonical BRCA1-A DNA-repair adaptor.
existing_annotations:
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  review:
    summary: Nuclear localization is supported as a minor/stress-induced pool.
    action: ACCEPT
    reason: Although ABRAXAS2 is mainly cytoplasmic, several studies report nuclear localization or nuclear translocation during DNA damage/oxidative stress, so nucleus annotations are acceptable when not interpreted as BRCA1-A complex membership [PMID:22974638; PMID:25283148].
    supported_by:
    - reference_id: PMID:25283148
      supporting_text: DNA-damage induced accumulation of endogenous ABRO1 as well as translocation of ABRO1 to the nucleus
    - reference_id: PMID:22974638
      supporting_text: during cellular stress it enters the nucleus and co-localizes with ATF4
    - reference_id: PMID:24075985
      supporting_text: presence of the BRISC-SHMT complex in both the cytoplasm and nucleus
- term:
    id: GO:0008017
    label: microtubule binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: microtubule binding is supported by ABRAXAS2/BRISC localization to mitotic microtubule structures and functional spindle defects after BRISC depletion.
    action: ACCEPT
    reason: PMID:26195665 directly shows ABRAXAS2/BRISC binds microtubules, localizes to K-fiber minus ends and spindle poles, and promotes bipolar spindle assembly through NUMA1 deubiquitination. This is an experimentally supported ABRAXAS2 cellular role rather than a generic cell-cycle phenotype.
    supported_by:
    - reference_id: PMID:26195665
      supporting_text: BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
    - reference_id: PMID:26195665
      supporting_text: promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
- term:
    id: GO:0008608
    label: attachment of spindle microtubules to kinetochore
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: attachment of spindle microtubules to kinetochore is supported by ABRAXAS2/BRISC localization to mitotic microtubule structures and functional spindle defects after BRISC depletion.
    action: ACCEPT
    reason: PMID:26195665 directly shows ABRAXAS2/BRISC binds microtubules, localizes to K-fiber minus ends and spindle poles, and promotes bipolar spindle assembly through NUMA1 deubiquitination. This is an experimentally supported ABRAXAS2 cellular role rather than a generic cell-cycle phenotype.
    supported_by:
    - reference_id: PMID:26195665
      supporting_text: BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
    - reference_id: PMID:26195665
      supporting_text: promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
- term:
    id: GO:0031593
    label: polyubiquitin modification-dependent protein binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: ABRAXAS2 participates in a K63-ubiquitin-directed BRISC complex, but direct polyubiquitin-dependent binding should not be treated as an independently enabled ABRAXAS2 molecular function.
    action: MARK_AS_OVER_ANNOTATED
    reason: The term is related to the K63-ubiquitin substrate-recognition biology of BRISC, but ABRAXAS2 is best interpreted as a noncatalytic scaffold/adaptor within the complex. The over-annotation concern is specifically that this annotation says ABRAXAS2 individually enables polyubiquitin-dependent binding, whereas the stronger evidence is that the BRISC complex processes K63-linked ubiquitin chains. The core annotation should emphasize BRISC complex membership and participation in K63-linked deubiquitination contexts rather than direct enabling of polyubiquitin-dependent binding by ABRAXAS2 itself.
    additional_reference_ids:
    - PMID:31253574
    supported_by:
    - reference_id: PMID:19214193
      supporting_text: the activity was intrinsic to PA700 and the Brcc36 isopeptidase complex (BRISC)
    - reference_id: PMID:20656690
      supporting_text: KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
    - reference_id: PMID:31253574
      supporting_text: Both BRCC36-containing complexes are specific for lysine-63-linked ubiquitin (K63-Ub) chains
- term:
    id: GO:0090307
    label: mitotic spindle assembly
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: mitotic spindle assembly is supported by ABRAXAS2/BRISC localization to mitotic microtubule structures and functional spindle defects after BRISC depletion.
    action: ACCEPT
    reason: PMID:26195665 directly shows ABRAXAS2/BRISC binds microtubules, localizes to K-fiber minus ends and spindle poles, and promotes bipolar spindle assembly through NUMA1 deubiquitination. This is an experimentally supported ABRAXAS2 cellular role rather than a generic cell-cycle phenotype.
    supported_by:
    - reference_id: PMID:26195665
      supporting_text: BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
    - reference_id: PMID:26195665
      supporting_text: promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
- term:
    id: GO:0000922
    label: spindle pole
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: Spindle-pole localization is supported by mitotic imaging.
    action: ACCEPT
    reason: ABRAXAS2/BRISC localizes to centrosomes and spindle poles during mitosis [PMID:26195665].
    supported_by:
    - reference_id: PMID:26195665
      supporting_text: ABRO1 was shown to be located at the centrosomes in interphase
    - reference_id: PMID:26195665
      supporting_text: BRISC localizes at centrosomes, spindle poles, and midbody during mitosis.
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: Nuclear localization is supported as a minor/stress-induced pool.
    action: ACCEPT
    reason: Although ABRAXAS2 is mainly cytoplasmic, several studies report nuclear localization or nuclear translocation during DNA damage/oxidative stress, so nucleus annotations are acceptable when not interpreted as BRCA1-A complex membership [PMID:22974638; PMID:25283148].
    supported_by:
    - reference_id: PMID:25283148
      supporting_text: DNA-damage induced accumulation of endogenous ABRO1 as well as translocation of ABRO1 to the nucleus
    - reference_id: PMID:22974638
      supporting_text: during cellular stress it enters the nucleus and co-localizes with ATF4
    - reference_id: PMID:24075985
      supporting_text: presence of the BRISC-SHMT complex in both the cytoplasm and nucleus
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: Cytoplasmic localization is well supported.
    action: ACCEPT
    reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
    supported_by:
    - reference_id: PMID:20656690
      supporting_text: KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
    - reference_id: PMID:21282113
      supporting_text: ABRO1 is mainly localized in the cytoplasm.
- term:
    id: GO:0005856
    label: cytoskeleton
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: Cytoskeleton is directionally correct but too broad for the available evidence.
    action: MODIFY
    reason: ABRAXAS2/BRISC is specifically associated with microtubule structures, especially spindle poles and K-fiber minus ends. The broader cytoskeleton term should be replaced with microtubule/spindle-related components.
    proposed_replacement_terms:
    - id: GO:0005874
      label: microtubule
    - id: GO:0000922
      label: spindle pole
    supported_by:
    - reference_id: PMID:26195665
      supporting_text: ABRO1 was shown to be located at the centrosomes in interphase
    - reference_id: PMID:26195665
      supporting_text: BRISC localizes at centrosomes, spindle poles, and midbody during mitosis.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:19615732
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from interaction-screen data.
    action: REMOVE
    reason: GO:0005515 does not describe ABRAXAS2 function. These interaction datasets may be useful as evidence for physical partners, but ABRAXAS2 should instead be represented by specific BRISC complex, K63-linked deubiquitination, microtubule, or pathway annotations when supported.
    supported_by:
    - reference_id: PMID:19615732
      supporting_text: We identified 774 candidate interacting proteins associated with 75 Dubs.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from interaction-screen data.
    action: REMOVE
    reason: GO:0005515 does not describe ABRAXAS2 function. These interaction datasets may be useful as evidence for physical partners, but ABRAXAS2 should instead be represented by specific BRISC complex, K63-linked deubiquitination, microtubule, or pathway annotations when supported.
    supported_by:
    - reference_id: PMID:32296183
      supporting_text: A reference map of the human binary protein interactome.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:33961781
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from interaction-screen data.
    action: REMOVE
    reason: GO:0005515 does not describe ABRAXAS2 function. These interaction datasets may be useful as evidence for physical partners, but ABRAXAS2 should instead be represented by specific BRISC complex, K63-linked deubiquitination, microtubule, or pathway annotations when supported.
    supported_by:
    - reference_id: PMID:33961781
      supporting_text: Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:36115835
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from interaction-screen data.
    action: REMOVE
    reason: GO:0005515 does not describe ABRAXAS2 function. These interaction datasets may be useful as evidence for physical partners, but ABRAXAS2 should instead be represented by specific BRISC complex, K63-linked deubiquitination, microtubule, or pathway annotations when supported.
    supported_by:
    - reference_id: PMID:36115835
      supporting_text: Quantitative fragmentomics allow affinity mapping of interactomes.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:37398436
  qualifier: enables
  review:
    summary: Generic protein-binding annotation from interaction-screen data.
    action: REMOVE
    reason: GO:0005515 does not describe ABRAXAS2 function. These interaction datasets may be useful as evidence for physical partners, but ABRAXAS2 should instead be represented by specific BRISC complex, K63-linked deubiquitination, microtubule, or pathway annotations when supported.
    supported_by:
    - reference_id: PMID:37398436
      supporting_text: AI-guided pipeline for protein-protein interaction drug discovery identifies a SARS-CoV-2 inhibitor.
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  qualifier: located_in
  review:
    summary: Cytosol localization is consistent with ABRAXAS2 as a major cytosolic BRISC scaffold.
    action: ACCEPT
    reason: Multiple studies describe ABRAXAS2/ABRO1/KIAA0157 as mainly cytoplasmic/cytosolic, while also allowing stress-induced nuclear pools.
    supported_by:
    - reference_id: PMID:20656690
      supporting_text: KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
    - reference_id: PMID:21282113
      supporting_text: ABRO1 is mainly localized in the cytoplasm.
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: EXP
  original_reference_id: PMID:21282113
  qualifier: located_in
  review:
    summary: Nuclear localization is supported as a minor/stress-induced pool.
    action: ACCEPT
    reason: Although ABRAXAS2 is mainly cytoplasmic, several studies report nuclear localization or nuclear translocation during DNA damage/oxidative stress, so nucleus annotations are acceptable when not interpreted as BRCA1-A complex membership [PMID:22974638; PMID:25283148].
    supported_by:
    - reference_id: PMID:25283148
      supporting_text: DNA-damage induced accumulation of endogenous ABRO1 as well as translocation of ABRO1 to the nucleus
    - reference_id: PMID:22974638
      supporting_text: during cellular stress it enters the nucleus and co-localizes with ATF4
    - reference_id: PMID:24075985
      supporting_text: presence of the BRISC-SHMT complex in both the cytoplasm and nucleus
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: EXP
  original_reference_id: PMID:22974638
  qualifier: located_in
  review:
    summary: Nuclear localization is supported as a minor/stress-induced pool.
    action: ACCEPT
    reason: Although ABRAXAS2 is mainly cytoplasmic, several studies report nuclear localization or nuclear translocation during DNA damage/oxidative stress, so nucleus annotations are acceptable when not interpreted as BRCA1-A complex membership [PMID:22974638; PMID:25283148].
    supported_by:
    - reference_id: PMID:25283148
      supporting_text: DNA-damage induced accumulation of endogenous ABRO1 as well as translocation of ABRO1 to the nucleus
    - reference_id: PMID:22974638
      supporting_text: during cellular stress it enters the nucleus and co-localizes with ATF4
    - reference_id: PMID:24075985
      supporting_text: presence of the BRISC-SHMT complex in both the cytoplasm and nucleus
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: EXP
  original_reference_id: PMID:24075985
  qualifier: located_in
  review:
    summary: Nuclear localization is supported as a minor/stress-induced pool.
    action: ACCEPT
    reason: Although ABRAXAS2 is mainly cytoplasmic, several studies report nuclear localization or nuclear translocation during DNA damage/oxidative stress, so nucleus annotations are acceptable when not interpreted as BRCA1-A complex membership [PMID:22974638; PMID:25283148].
    supported_by:
    - reference_id: PMID:25283148
      supporting_text: DNA-damage induced accumulation of endogenous ABRO1 as well as translocation of ABRO1 to the nucleus
    - reference_id: PMID:22974638
      supporting_text: during cellular stress it enters the nucleus and co-localizes with ATF4
    - reference_id: PMID:24075985
      supporting_text: presence of the BRISC-SHMT complex in both the cytoplasm and nucleus
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: EXP
  original_reference_id: PMID:25283148
  qualifier: located_in
  review:
    summary: Nuclear localization is supported as a minor/stress-induced pool.
    action: ACCEPT
    reason: Although ABRAXAS2 is mainly cytoplasmic, several studies report nuclear localization or nuclear translocation during DNA damage/oxidative stress, so nucleus annotations are acceptable when not interpreted as BRCA1-A complex membership [PMID:22974638; PMID:25283148].
    supported_by:
    - reference_id: PMID:25283148
      supporting_text: DNA-damage induced accumulation of endogenous ABRO1 as well as translocation of ABRO1 to the nucleus
    - reference_id: PMID:22974638
      supporting_text: during cellular stress it enters the nucleus and co-localizes with ATF4
    - reference_id: PMID:24075985
      supporting_text: presence of the BRISC-SHMT complex in both the cytoplasm and nucleus
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: EXP
  original_reference_id: PMID:20656690
  qualifier: located_in
  review:
    summary: Cytoplasmic localization is well supported.
    action: ACCEPT
    reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
    supported_by:
    - reference_id: PMID:20656690
      supporting_text: KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
    - reference_id: PMID:21282113
      supporting_text: ABRO1 is mainly localized in the cytoplasm.
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: EXP
  original_reference_id: PMID:21282113
  qualifier: located_in
  review:
    summary: Cytoplasmic localization is well supported.
    action: ACCEPT
    reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
    supported_by:
    - reference_id: PMID:20656690
      supporting_text: KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
    - reference_id: PMID:21282113
      supporting_text: ABRO1 is mainly localized in the cytoplasm.
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: EXP
  original_reference_id: PMID:22974638
  qualifier: located_in
  review:
    summary: Cytoplasmic localization is well supported.
    action: ACCEPT
    reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
    supported_by:
    - reference_id: PMID:20656690
      supporting_text: KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
    - reference_id: PMID:21282113
      supporting_text: ABRO1 is mainly localized in the cytoplasm.
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: EXP
  original_reference_id: PMID:25283148
  qualifier: located_in
  review:
    summary: Cytoplasmic localization is well supported.
    action: ACCEPT
    reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
    supported_by:
    - reference_id: PMID:20656690
      supporting_text: KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
    - reference_id: PMID:21282113
      supporting_text: ABRO1 is mainly localized in the cytoplasm.
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IPI
  original_reference_id: PMID:31253574
  qualifier: located_in
  review:
    summary: Cytoplasmic localization is well supported.
    action: ACCEPT
    reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
    supported_by:
    - reference_id: PMID:20656690
      supporting_text: KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
    - reference_id: PMID:21282113
      supporting_text: ABRO1 is mainly localized in the cytoplasm.
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: NAS
  original_reference_id: PMID:31253574
  qualifier: located_in
  review:
    summary: Cytoplasmic localization is well supported.
    action: ACCEPT
    reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
    supported_by:
    - reference_id: PMID:20656690
      supporting_text: KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
    - reference_id: PMID:21282113
      supporting_text: ABRO1 is mainly localized in the cytoplasm.
- term:
    id: GO:0034516
    label: response to vitamin B6
  evidence_type: NAS
  original_reference_id: PMID:31142841
  qualifier: involved_in
  review:
    summary: Vitamin B6/PLP regulates SHMT2 oligomer state and thus BRISC-SHMT2 assembly, but ABRAXAS2 is not best described as executing a vitamin B6 response.
    action: MODIFY
    reason: The supported ABRAXAS2 process in this study is BRISC-SHMT2-dependent positive regulation of type I interferon signaling. PLP is the metabolite that shifts SHMT2 dimer/tetramer state and thereby modulates BRISC-SHMT2 interaction; annotating ABRAXAS2 itself to response to vitamin B6 overstates the causal process. The same ComplexPortal NAS annotation may merit reassessment for the other BRISC subunits annotated from this study.
    proposed_replacement_terms:
    - id: GO:0060340
      label: positive regulation of type I interferon-mediated signaling pathway
    supported_by:
    - reference_id: PMID:31142841
      supporting_text: Intracellular levels of PLP regulate the interaction between BRISC and SHMT2, as well as inflammatory cytokine responses.
    - reference_id: PMID:31142841
      supporting_text: Mutations in BRISC that disrupt SHMT2 binding impair type I interferon signalling in response to inflammatory stimuli.
- term:
    id: GO:0070552
    label: BRISC complex
  evidence_type: IPI
  original_reference_id: PMID:31253574
  qualifier: part_of
  review:
    summary: ABRAXAS2 is a bona fide BRISC complex subunit.
    action: ACCEPT
    reason: Multiple biochemical, structural, UniProt, and ComplexPortal sources identify ABRAXAS2/ABRO1 as the BRISC-specific scaffold paired with BRCC36/BRCC3, BABAM1/MERIT40, and BABAM2/BRE. This is the safest PN-projected annotation and is already in GOA.
    additional_reference_ids:
    - file:human/ABRAXAS2/ABRAXAS2-deep-research-falcon.md
    supported_by:
    - reference_id: PMID:21282113
      supporting_text: ABRO1 complex does not interact with BRCA1
    - reference_id: PMID:31253574
      supporting_text: in BRCA1-A, BRCC36 is supported by ABRAXAS (Wang et al., 2007), whereas in BRISC, it is paired with ABRO1
    - reference_id: file:human/ABRAXAS2/ABRAXAS2-deep-research-falcon.md
      supporting_text: '**ABRAXAS2/ABRO1 is a core scaffold subunit of BRISC**'
- term:
    id: GO:0070552
    label: BRISC complex
  evidence_type: NAS
  original_reference_id: PMID:31253574
  qualifier: part_of
  review:
    summary: ABRAXAS2 is a bona fide BRISC complex subunit.
    action: ACCEPT
    reason: Multiple biochemical, structural, UniProt, and ComplexPortal sources identify ABRAXAS2/ABRO1 as the BRISC-specific scaffold paired with BRCC36/BRCC3, BABAM1/MERIT40, and BABAM2/BRE. This is the safest PN-projected annotation and is already in GOA.
    supported_by:
    - reference_id: PMID:21282113
      supporting_text: ABRO1 complex does not interact with BRCA1
    - reference_id: PMID:31253574
      supporting_text: in BRCA1-A, BRCC36 is supported by ABRAXAS (Wang et al., 2007), whereas in BRISC, it is paired with ABRO1
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:26195665
  qualifier: enables
  review:
    summary: Generic protein-binding annotation for the ABRAXAS2/NUMA1 interaction.
    action: REMOVE
    reason: The interaction is biologically important, but GO:0005515 is uninformative. The same paper supports the more specific ABRAXAS2/BRISC roles in microtubule binding, mitotic spindle assembly, and K63-linked deubiquitination of NUMA1 [PMID:26195665].
    supported_by:
    - reference_id: PMID:26195665
      supporting_text: BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
    - reference_id: PMID:26195665
      supporting_text: promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-5691439
  qualifier: located_in
  review:
    summary: Cytosol localization is consistent with ABRAXAS2 as a major cytosolic BRISC scaffold.
    action: ACCEPT
    reason: Multiple studies describe ABRAXAS2/ABRO1/KIAA0157 as mainly cytoplasmic/cytosolic, while also allowing stress-induced nuclear pools.
    supported_by:
    - reference_id: Reactome:R-HSA-5691439
      supporting_text: FAM175B (ABRO1), another BRISC subunit, binds directly to NLRP3 leading to FAM175B-dependent recruitment of the BRISC complex
- term:
    id: GO:0000278
    label: mitotic cell cycle
  evidence_type: IMP
  original_reference_id: PMID:26195665
  qualifier: involved_in
  review:
    summary: Mitotic cell cycle is supported but too broad relative to the specific spindle defects.
    action: MODIFY
    reason: ABRAXAS2/BRISC depletion affects mitosis through spindle assembly, kinetochore-microtubule attachment, and chromosome segregation. More specific existing terms capture this biology better than the broad mitotic cell cycle term.
    proposed_replacement_terms:
    - id: GO:0090307
      label: mitotic spindle assembly
    - id: GO:0008608
      label: attachment of spindle microtubules to kinetochore
    - id: GO:0007059
      label: chromosome segregation
    supported_by:
    - reference_id: PMID:26195665
      supporting_text: BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
    - reference_id: PMID:26195665
      supporting_text: promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IDA
  original_reference_id: PMID:24075985
  qualifier: located_in
  review:
    summary: Cytoplasmic localization is well supported.
    action: ACCEPT
    reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
    supported_by:
    - reference_id: PMID:20656690
      supporting_text: KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
    - reference_id: PMID:21282113
      supporting_text: ABRO1 is mainly localized in the cytoplasm.
- term:
    id: GO:0005813
    label: centrosome
  evidence_type: IDA
  original_reference_id: PMID:26195665
  qualifier: colocalizes_with
  review:
    summary: Centrosome colocalization is experimentally supported in mitotic-cell imaging.
    action: ACCEPT
    reason: ABRAXAS2/BRISC localizes to centrosomes and spindle poles during the cell cycle [PMID:26195665].
    supported_by:
    - reference_id: PMID:26195665
      supporting_text: ABRO1 was shown to be located at the centrosomes in interphase
    - reference_id: PMID:26195665
      supporting_text: BRISC localizes at centrosomes, spindle poles, and midbody during mitosis.
- term:
    id: GO:0007059
    label: chromosome segregation
  evidence_type: IMP
  original_reference_id: PMID:26195665
  qualifier: involved_in
  review:
    summary: Chromosome-segregation defects follow ABRAXAS2/BRISC depletion.
    action: ACCEPT
    reason: ABRAXAS2 depletion produces lagging chromosomes and spindle defects, supporting involvement in chromosome segregation through its spindle assembly role [PMID:26195665].
    supported_by:
    - reference_id: PMID:26195665
      supporting_text: BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
    - reference_id: PMID:26195665
      supporting_text: promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
- term:
    id: GO:0008017
    label: microtubule binding
  evidence_type: IDA
  original_reference_id: PMID:26195665
  qualifier: enables
  review:
    summary: microtubule binding is supported by ABRAXAS2/BRISC localization to mitotic microtubule structures and functional spindle defects after BRISC depletion.
    action: ACCEPT
    reason: PMID:26195665 directly shows ABRAXAS2/BRISC binds microtubules, localizes to K-fiber minus ends and spindle poles, and promotes bipolar spindle assembly through NUMA1 deubiquitination. This is an experimentally supported ABRAXAS2 cellular role rather than a generic cell-cycle phenotype.
    supported_by:
    - reference_id: PMID:26195665
      supporting_text: BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
    - reference_id: PMID:26195665
      supporting_text: promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
- term:
    id: GO:0008608
    label: attachment of spindle microtubules to kinetochore
  evidence_type: IMP
  original_reference_id: PMID:26195665
  qualifier: involved_in
  review:
    summary: attachment of spindle microtubules to kinetochore is supported by ABRAXAS2/BRISC localization to mitotic microtubule structures and functional spindle defects after BRISC depletion.
    action: ACCEPT
    reason: PMID:26195665 directly shows ABRAXAS2/BRISC binds microtubules, localizes to K-fiber minus ends and spindle poles, and promotes bipolar spindle assembly through NUMA1 deubiquitination. This is an experimentally supported ABRAXAS2 cellular role rather than a generic cell-cycle phenotype.
    supported_by:
    - reference_id: PMID:26195665
      supporting_text: BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
    - reference_id: PMID:26195665
      supporting_text: promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
- term:
    id: GO:0030496
    label: midbody
  evidence_type: IDA
  original_reference_id: PMID:26195665
  qualifier: colocalizes_with
  review:
    summary: midbody localization is supported by mitotic imaging.
    action: ACCEPT
    reason: ABRAXAS2/BRISC was observed at centrosomes, spindle poles, K-fiber minus ends, and midbody during mitosis [PMID:26195665].
    supported_by:
    - reference_id: PMID:26195665
      supporting_text: ABRO1 was shown to be located at the centrosomes in interphase
    - reference_id: PMID:26195665
      supporting_text: BRISC localizes at centrosomes, spindle poles, and midbody during mitosis.
- term:
    id: GO:0031616
    label: spindle pole centrosome
  evidence_type: IDA
  original_reference_id: PMID:26195665
  qualifier: colocalizes_with
  review:
    summary: spindle pole centrosome localization is supported by mitotic imaging.
    action: ACCEPT
    reason: ABRAXAS2/BRISC was observed at centrosomes, spindle poles, K-fiber minus ends, and midbody during mitosis [PMID:26195665].
    supported_by:
    - reference_id: PMID:26195665
      supporting_text: ABRO1 was shown to be located at the centrosomes in interphase
    - reference_id: PMID:26195665
      supporting_text: BRISC localizes at centrosomes, spindle poles, and midbody during mitosis.
- term:
    id: GO:0036449
    label: microtubule minus-end
  evidence_type: IDA
  original_reference_id: PMID:26195665
  qualifier: colocalizes_with
  review:
    summary: microtubule minus-end localization is supported by mitotic imaging.
    action: ACCEPT
    reason: ABRAXAS2/BRISC was observed at centrosomes, spindle poles, K-fiber minus ends, and midbody during mitosis [PMID:26195665].
    supported_by:
    - reference_id: PMID:26195665
      supporting_text: ABRO1 was shown to be located at the centrosomes in interphase
    - reference_id: PMID:26195665
      supporting_text: BRISC localizes at centrosomes, spindle poles, and midbody during mitosis.
- term:
    id: GO:0070536
    label: protein K63-linked deubiquitination
  evidence_type: IMP
  original_reference_id: PMID:24075985
  qualifier: involved_in
  review:
    summary: Protein K63-linked deubiquitination is the central BRISC pathway function involving ABRAXAS2.
    action: ACCEPT
    reason: ABRAXAS2 is not the catalytic subunit, but it is a required scaffold/adaptor of BRISC, the BRCC36/BRCC3 K63-linked DUB complex. The cited studies support substrate-specific K63 deubiquitination of IFNAR1 or NUMA1 by ABRAXAS2-containing BRISC.
    supported_by:
    - reference_id: PMID:24075985
      supporting_text: SHMT directs BRISC activity at K63-Ub chains conjugated to the type 1 interferon (IFN) receptor chain 1 (IFNAR1).
    - reference_id: PMID:31142841
      supporting_text: Direct interaction with SHMT2 enhances BRISC delivery to ubiquitylated type I interferon (IFN) receptors (IFNAR1/2)
- term:
    id: GO:0070536
    label: protein K63-linked deubiquitination
  evidence_type: IMP
  original_reference_id: PMID:26195665
  qualifier: involved_in
  review:
    summary: Protein K63-linked deubiquitination is the central BRISC pathway function involving ABRAXAS2.
    action: ACCEPT
    reason: ABRAXAS2 is not the catalytic subunit, but it is a required scaffold/adaptor of BRISC, the BRCC36/BRCC3 K63-linked DUB complex. The cited studies support substrate-specific K63 deubiquitination of IFNAR1 or NUMA1 by ABRAXAS2-containing BRISC.
    supported_by:
    - reference_id: PMID:26195665
      supporting_text: BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
    - reference_id: PMID:26195665
      supporting_text: promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
- term:
    id: GO:0070552
    label: BRISC complex
  evidence_type: IDA
  original_reference_id: PMID:24075985
  qualifier: part_of
  review:
    summary: ABRAXAS2 is a bona fide BRISC complex subunit.
    action: ACCEPT
    reason: Multiple biochemical, structural, UniProt, and ComplexPortal sources identify ABRAXAS2/ABRO1 as the BRISC-specific scaffold paired with BRCC36/BRCC3, BABAM1/MERIT40, and BABAM2/BRE. This is the safest PN-projected annotation and is already in GOA.
    supported_by:
    - reference_id: PMID:21282113
      supporting_text: ABRO1 complex does not interact with BRCA1
    - reference_id: PMID:31253574
      supporting_text: in BRCA1-A, BRCC36 is supported by ABRAXAS (Wang et al., 2007), whereas in BRISC, it is paired with ABRO1
- term:
    id: GO:0090307
    label: mitotic spindle assembly
  evidence_type: IMP
  original_reference_id: PMID:26195665
  qualifier: involved_in
  review:
    summary: mitotic spindle assembly is supported by ABRAXAS2/BRISC localization to mitotic microtubule structures and functional spindle defects after BRISC depletion.
    action: ACCEPT
    reason: PMID:26195665 directly shows ABRAXAS2/BRISC binds microtubules, localizes to K-fiber minus ends and spindle poles, and promotes bipolar spindle assembly through NUMA1 deubiquitination. This is an experimentally supported ABRAXAS2 cellular role rather than a generic cell-cycle phenotype.
    supported_by:
    - reference_id: PMID:26195665
      supporting_text: BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
    - reference_id: PMID:26195665
      supporting_text: promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
- term:
    id: GO:0002931
    label: response to ischemia
  evidence_type: IMP
  original_reference_id: PMID:21195082
  qualifier: involved_in
  review:
    summary: Response to ischemia is supported in a cardiac injury model but is context-specific.
    action: KEEP_AS_NON_CORE
    reason: ABRO1 protein increases after myocardial ischemia/reperfusion and knockdown exacerbates cardiomyocyte damage, supporting the annotation. This is a tissue/stress phenotype rather than the core molecular function of ABRAXAS2.
    supported_by:
    - reference_id: PMID:21195082
      supporting_text: Reducing the Abro1 protein level exacerbated cellular damage and cell death of cardiomyocytes due to MI/R injury.
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IDA
  original_reference_id: PMID:21195082
  qualifier: located_in
  review:
    summary: Cytoplasmic localization is well supported.
    action: ACCEPT
    reason: ABRAXAS2/ABRO1 is predominantly cytoplasmic and acts as the scaffold for cytoplasmic BRISC, with additional stress- and mitosis-specific localizations [PMID:20656690; PMID:21282113; PMID:24075985; PMID:26195665].
    supported_by:
    - reference_id: PMID:20656690
      supporting_text: KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
    - reference_id: PMID:21282113
      supporting_text: ABRO1 is mainly localized in the cytoplasm.
- term:
    id: GO:0070552
    label: BRISC complex
  evidence_type: IDA
  original_reference_id: PMID:19214193
  qualifier: part_of
  review:
    summary: ABRAXAS2 is a bona fide BRISC complex subunit.
    action: ACCEPT
    reason: Multiple biochemical, structural, UniProt, and ComplexPortal sources identify ABRAXAS2/ABRO1 as the BRISC-specific scaffold paired with BRCC36/BRCC3, BABAM1/MERIT40, and BABAM2/BRE. This is the safest PN-projected annotation and is already in GOA.
    supported_by:
    - reference_id: PMID:21282113
      supporting_text: ABRO1 complex does not interact with BRCA1
    - reference_id: PMID:31253574
      supporting_text: in BRCA1-A, BRCC36 is supported by ABRAXAS (Wang et al., 2007), whereas in BRISC, it is paired with ABRO1
- term:
    id: GO:0031593
    label: polyubiquitin modification-dependent protein binding
  evidence_type: IDA
  original_reference_id: PMID:19261749
  qualifier: enables
  review:
    summary: Polyubiquitin-dependent binding is plausible for the BRCC36 complex family, but this PMID directly concerns BRCA1-A rather than ABRAXAS2-containing BRISC.
    action: MARK_AS_OVER_ANNOTATED
    reason: ABRAXAS2-containing BRISC is a K63-ubiquitin-directed DUB complex, but the cited paper supports polyubiquitin-chain binding in the BRCA1-A complex, not direct ABRAXAS2 binding. Later structural and functional studies support BRISC ubiquitin-chain processing and substrate targeting, so the biological context is related, but this IDA annotation overstates direct evidence for ABRAXAS2 as the enabling binder [PMID:19261749; PMID:31253574].
    additional_reference_ids:
    - PMID:31253574
    supported_by:
    - reference_id: PMID:19261749
      supporting_text: four members of the BRCA1-A complex possess a polyubiquitin chain-binding capability
- term:
    id: GO:0060340
    label: positive regulation of type I interferon-mediated signaling pathway
  evidence_type: IMP
  original_reference_id: PMID:24075985
  qualifier: involved_in
  review:
    summary: 'NEW annotation: ABRAXAS2-containing BRISC promotes type I interferon signaling by deubiquitinating/stabilizing IFNAR1.'
    action: NEW
    reason: BRISC-SHMT targets K63-ubiquitinated IFNAR1, limits receptor internalization/degradation, and is required for full interferon responses. The GO term is more specific and better supported than a broad vitamin B6-response annotation.
    additional_reference_ids:
    - PMID:31142841
    supported_by:
    - reference_id: PMID:24075985
      supporting_text: SHMT directs BRISC activity at K63-Ub chains conjugated to the type 1 interferon (IFN) receptor chain 1 (IFNAR1).
    - reference_id: PMID:31142841
      supporting_text: Direct interaction with SHMT2 enhances BRISC delivery to ubiquitylated type I interferon (IFN) receptors (IFNAR1/2)
- term:
    id: GO:0043517
    label: positive regulation of DNA damage response, signal transduction by p53 class mediator
  evidence_type: IMP
  original_reference_id: PMID:25283148
  qualifier: involved_in
  review:
    summary: 'NEW annotation: ABRAXAS2/ABRO1 positively regulates p53-mediated DNA-damage signaling.'
    action: NEW
    reason: The supported DNA-damage role is p53 stabilization and p53-dependent DNA-damage response, not direct DNA repair. This is why the PN-projected broad GO:0006281 DNA repair term is not proposed as a direct ABRAXAS2 annotation here.
    supported_by:
    - reference_id: PMID:25283148
      supporting_text: ABRO1 stabilizes p53 by facilitating the interaction of p53 with USP7.
    - reference_id: PMID:25283148
      supporting_text: the induction of p53 by DNA damage is almost completely attenuated by ABRO1 depletion
references:
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings:
  - statement: PANTHER phylogenetic annotations propagate conserved ABRAXAS2/ABRO1 family localization, microtubule, ubiquitin-chain binding, and mitotic spindle terms.
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping
  findings:
  - statement: UniProt subcellular-location keyword mapping supports broad nucleus, cytoplasm, cytoskeleton, and spindle-pole cellular component annotations.
- id: GO_REF:0000052
  title: Gene Ontology annotation based on curation of immunofluorescence data
  findings:
  - statement: Human Protein Atlas immunofluorescence curation supports ABRAXAS2 cytosol localization.
- id: PMID:19214193
  title: 'K63-specific deubiquitination by two JAMM/MPN+ complexes: BRISC-associated Brcc36 and proteasomal Poh1.'
  findings:
  - statement: Biochemical fractionation identifies BRISC as a Brcc36-containing K63-specific deubiquitinating complex.
    supporting_text: the activity was intrinsic to PA700 and the Brcc36 isopeptidase complex (BRISC)
    reference_section_type: ABSTRACT
- id: PMID:19261749
  title: NBA1, a new player in the Brca1 A complex, is required for DNA damage resistance and checkpoint control.
  findings:
  - statement: The BRCA1-A complex study supports polyubiquitin-chain binding by related complex components, but its direct evidence is for BRCA1-A/ABRAXAS1 rather than ABRAXAS2/BRISC.
    supporting_text: four members of the BRCA1-A complex possess a polyubiquitin chain-binding capability
    reference_section_type: ABSTRACT
- id: PMID:19615732
  title: Defining the human deubiquitinating enzyme interaction landscape.
  findings:
  - statement: Proteomic interactome mapping places ABRAXAS2 among DUB-associated interaction data but does not by itself define an informative GO molecular function beyond generic protein binding.
    supporting_text: We identified 774 candidate interacting proteins associated with 75 Dubs.
    reference_section_type: ABSTRACT
- id: PMID:20656690
  title: The Lys63-specific deubiquitinating enzyme BRCC36 is regulated by two scaffold proteins localizing in different subcellular compartments.
  findings:
  - statement: KIAA0157/ABRAXAS2 is a cytosolic scaffold that activates BRCC36 in the BRISC complex and distinguishes BRISC from nuclear BRCA1-A.
    supporting_text: KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
    reference_section_type: ABSTRACT
- id: PMID:21195082
  title: Regulation of Abro1/KIAA0157 during myocardial infarction and cell death reveals a novel cardioprotective mechanism for Lys63-specific deubiquitination.
  findings:
  - statement: ABRO1 is induced in myocardial ischemia/reperfusion and contributes to cardioprotection through K63-linked deubiquitination.
    supporting_text: Reducing the Abro1 protein level exacerbated cellular damage and cell death of cardiomyocytes due to MI/R injury.
    reference_section_type: ABSTRACT
- id: PMID:21282113
  title: NBA1/MERIT40 and BRE interaction is required for the integrity of two distinct deubiquitinating enzyme BRCC36-containing complexes.
  findings:
  - statement: ABRO1-containing BRISC is mainly cytoplasmic, lacks the BRCA1-interacting motif, and does not interact with BRCA1.
    supporting_text: Because it lacks the BRCA1-interacting motif, the ABRO1 complex does not interact with BRCA1.
    reference_section_type: ABSTRACT
- id: PMID:22974638
  title: ATF4 interacts with Abro1/KIAA0157 scaffold protein and participates in a cytoprotective pathway.
  findings:
  - statement: ABRO1 can enter the nucleus during cellular stress and interact with ATF4 in a cytoprotective pathway.
    supporting_text: Abro1 is predominantly cytoplasmic, but during cellular stress it enters the nucleus and co-localizes with ATF4.
    reference_section_type: ABSTRACT
- id: PMID:24075985
  title: A BRISC-SHMT complex deubiquitinates IFNAR1 and regulates interferon responses.
  findings:
  - statement: SHMT2 targets BRISC to K63-ubiquitinated IFNAR1, promoting receptor deubiquitination and type I interferon responses.
    supporting_text: SHMT directs BRISC activity at K63-Ub chains conjugated to the type 1 interferon (IFN) receptor chain 1 (IFNAR1).
    reference_section_type: ABSTRACT
- id: PMID:25283148
  title: ABRO1 suppresses tumourigenesis and regulates the DNA damage response by stabilizing p53.
  findings:
  - statement: ABRO1 promotes p53 stability by facilitating USP7-p53 interaction and is induced/translocated after DNA damage.
    supporting_text: ABRO1 stabilizes p53 by facilitating the interaction of p53 with USP7.
    reference_section_type: ABSTRACT
- id: PMID:26195665
  title: The deubiquitinating enzyme complex BRISC is required for proper mitotic spindle assembly in mammalian cells.
  findings:
  - statement: BRISC localizes to microtubule minus ends and spindle poles, binds microtubules, and promotes spindle assembly by deubiquitinating NUMA.
    supporting_text: BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
    reference_section_type: ABSTRACT
- id: PMID:31142841
  title: Metabolic control of BRISC-SHMT2 assembly regulates immune signalling.
  findings:
  - statement: PLP-dependent SHMT2 oligomerization regulates BRISC-SHMT2 assembly and type I interferon signaling.
    supporting_text: Mutations in BRISC that disrupt SHMT2 binding impair type I interferon signalling in response to inflammatory stimuli.
    reference_section_type: ABSTRACT
- id: PMID:31253574
  title: Structural Basis of BRCC36 Function in DNA Repair and Immune Regulation.
  findings:
  - statement: Structures distinguish ABRAXAS/BRCA1-A DNA-repair targeting from ABRO1/BRISC immune-stress signaling and SHMT2 regulation.
    supporting_text: The BRCA1-A and BRISC complexes serve in DNA double-strand break repair and immune signaling
    reference_section_type: ABSTRACT
- id: PMID:32296183
  title: A reference map of the human binary protein interactome.
  findings:
  - statement: Large-scale binary interactome data support generic interaction evidence but not a specific ABRAXAS2 molecular function.
    supporting_text: A reference map of the human binary protein interactome.
    reference_section_type: RESULTS
- id: PMID:33961781
  title: Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.
  findings:
  - statement: Proteome-scale AP-MS interaction data support generic interaction evidence but not a specific ABRAXAS2 molecular function.
    supporting_text: Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.
    reference_section_type: RESULTS
- id: PMID:36115835
  title: Quantitative fragmentomics allow affinity mapping of interactomes.
  findings:
  - statement: Fragment-level interactome data support generic interaction evidence but not a specific ABRAXAS2 molecular function.
    supporting_text: Quantitative fragmentomics allow affinity mapping of interactomes.
    reference_section_type: ABSTRACT
- id: PMID:37398436
  title: AI-guided pipeline for protein-protein interaction drug discovery identifies a SARS-CoV-2 inhibitor.
  findings:
  - statement: A preprint interactome/drug-discovery pipeline reports generic interaction evidence that is not an informative ABRAXAS2 GO function.
    supporting_text: AI-guided pipeline for protein-protein interaction drug discovery identifies a SARS-CoV-2 inhibitor.
    reference_section_type: ABSTRACT
- id: Reactome:R-HSA-5691439
  title: BRISC complex deubiquitinates NLRP3
  findings:
  - statement: Reactome places ABRO1/FAM175B in cytosolic BRISC-mediated K63 deubiquitination of NLRP3.
    supporting_text: FAM175B (ABRO1), another BRISC subunit, binds directly to NLRP3 leading to FAM175B-dependent recruitment of the BRISC complex
    reference_section_type: RESULTS
- id: file:human/ABRAXAS2/ABRAXAS2-notes.md
  title: ABRAXAS2 review notes
  findings:
  - statement: Local notes summarize the Proteostasis Network projected context and the conservative decision not to propagate broad DNA repair from PN context alone.
- id: file:human/ABRAXAS2/ABRAXAS2-deep-research-falcon.md
  title: ABRAXAS2 Falcon deep research report
  findings:
  - statement: Falcon deep research produced a secondary synthesis for ABRAXAS2; it was used only as orientation because the primary curation decisions were checked against cached primary literature and project files.
aliases:
- ABRO1
- FAM175B
- KIAA0157
core_functions:
- description: ABRAXAS2 is the BRISC-specific MPN-domain scaffold/adaptor paired with BRCC3/BRCC36 in a K63-linked deubiquitinating complex. Its core role is not catalysis; instead, ABRAXAS2 organizes the BRISC assembly, helps determine cytoplasmic/nuclear targeting, and provides an interaction surface that distinguishes BRISC from ABRAXAS1-containing BRCA1-A. Through this complex, ABRAXAS2 supports K63-linked deubiquitination of substrates such as IFNAR1 and NUMA1, with NLRP3 inflammasome recruitment supported as an additional BRISC substrate-targeting context.
  directly_involved_in:
  - id: GO:0070536
    label: protein K63-linked deubiquitination
  - id: GO:0060340
    label: positive regulation of type I interferon-mediated signaling pathway
  locations:
  - id: GO:0005829
    label: cytosol
  - id: GO:0005634
    label: nucleus
  in_complex:
    id: GO:0070552
    label: BRISC complex
  supported_by:
  - reference_id: PMID:19214193
    supporting_text: the activity was intrinsic to PA700 and the Brcc36 isopeptidase complex (BRISC)
  - reference_id: PMID:20656690
    supporting_text: KIAA0157 mainly localizes in cytosol and activates BRCC36 in the cytoplasm.
  - reference_id: PMID:24075985
    supporting_text: SHMT directs BRISC activity at K63-Ub chains conjugated to the type 1 interferon (IFN) receptor chain 1 (IFNAR1).
  - reference_id: PMID:31142841
    supporting_text: Direct interaction with SHMT2 enhances BRISC delivery to ubiquitylated type I interferon (IFN) receptors (IFNAR1/2)
  - reference_id: PMID:21282113
    supporting_text: ABRO1 complex does not interact with BRCA1
  - reference_id: PMID:31253574
    supporting_text: in BRCA1-A, BRCC36 is supported by ABRAXAS (Wang et al., 2007), whereas in BRISC, it is paired with ABRO1
  - reference_id: Reactome:R-HSA-5691439
    supporting_text: FAM175B (ABRO1), another BRISC subunit, binds directly to NLRP3 leading to FAM175B-dependent recruitment of the BRISC complex
- molecular_function:
    id: GO:0008017
    label: microtubule binding
  description: ABRAXAS2-containing BRISC binds mitotic microtubule structures, accumulates at K-fiber minus ends, spindle poles, centrosomes, and midbody, and promotes functional bipolar spindle assembly. Mechanistically, BRISC deubiquitinates K63-linked ubiquitin chains on NUMA1, influencing NUMA1 interactions needed for spindle-pole organization and kinetochore-microtubule attachment.
  directly_involved_in:
  - id: GO:0090307
    label: mitotic spindle assembly
  - id: GO:0008608
    label: attachment of spindle microtubules to kinetochore
  - id: GO:0007059
    label: chromosome segregation
  - id: GO:0070536
    label: protein K63-linked deubiquitination
  locations:
  - id: GO:0000922
    label: spindle pole
  - id: GO:0031616
    label: spindle pole centrosome
  - id: GO:0036449
    label: microtubule minus-end
  - id: GO:0030496
    label: midbody
  supported_by:
  - reference_id: PMID:26195665
    supporting_text: BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs
  - reference_id: PMID:26195665
    supporting_text: promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA).
  - reference_id: PMID:26195665
    supporting_text: ABRO1 was shown to be located at the centrosomes in interphase
  - reference_id: PMID:26195665
    supporting_text: BRISC localizes at centrosomes, spindle poles, and midbody during mitosis.
- description: A secondary, stress-responsive ABRAXAS2 activity is p53 pathway regulation. ABRO1/ABRAXAS2 can accumulate and translocate to the nucleus after DNA damage, promotes USP7-p53 interaction, and stabilizes p53, thereby supporting p53-mediated DNA-damage signaling. This supports a specific p53-pathway process annotation but does not justify broad direct DNA repair annotation.
  directly_involved_in:
  - id: GO:0043517
    label: positive regulation of DNA damage response, signal transduction by p53 class mediator
  locations:
  - id: GO:0005634
    label: nucleus
  - id: GO:0005737
    label: cytoplasm
  supported_by:
  - reference_id: PMID:25283148
    supporting_text: ABRO1 stabilizes p53 by facilitating the interaction of p53 with USP7.
  - reference_id: PMID:25283148
    supporting_text: the induction of p53 by DNA damage is almost completely attenuated by ABRO1 depletion
  - reference_id: PMID:25283148
    supporting_text: DNA-damage induced accumulation of endogenous ABRO1 as well as translocation of ABRO1 to the nucleus
  - reference_id: PMID:22974638
    supporting_text: during cellular stress it enters the nucleus and co-localizes with ATF4
proposed_new_terms: []
suggested_questions:
- question: Does ABRAXAS2-containing BRISC directly participate in DNA repair, or is its DNA-damage role limited to p53 stabilization and stress-response signaling outside the BRCA1-A repair complex?
- question: Which ABRAXAS2/BRISC substrates besides IFNAR1, NLRP3, and NUMA1 are physiologically dominant in primary human tissues?
- question: Should BRISC-SHMT2 metabolite-sensitive regulation be represented in GO as interferon-signaling regulation rather than broad vitamin B6 response for each BRISC component?
suggested_experiments:
- description: Test ABRAXAS2 knockout and rescue with BRISC-assembly-defective and SHMT2-binding-defective ABRAXAS2 mutants in IFN-stimulated primary cells, measuring IFNAR1 K63 ubiquitination, receptor surface abundance, and STAT1 phosphorylation.
- description: Compare ABRAXAS2 and ABRAXAS1 recruitment after DNA double-strand breaks using live-cell imaging and chromatin fractionation, with BRCA1, RAP80, and p53/USP7 readouts, to separate direct DNA-repair targeting from p53-mediated DNA-damage signaling.
- description: Reconstitute purified human BRISC variants with NUMA1 fragments and K63-linked ubiquitin chains to test whether ABRAXAS2 microtubule-binding and scaffold regions control substrate selection during spindle assembly.