ABRAXAS1

UniProt ID: Q6UWZ7
Organism: Homo sapiens
Review Status: DRAFT
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Gene Description

ABRAXAS1 encodes a nuclear BRCA1-A complex subunit that acts as a scaffold linking BRCA1, UIMC1/RAP80, BRCC3/BRCC36, BABAM proteins, and ubiquitin-dependent DNA damage-site signaling. The protein contains an MPN-like domain, binds polyubiquitin as part of the BRCA1-A/RAP80 complex, and supports BRCA1 recruitment, DNA double-strand break repair, K63-ubiquitin signal editing by BRCC36, and G2/M DNA damage checkpoint responses.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0005634 nucleus
IBA
GO_REF:0000033
ACCEPT
Summary: Supported nuclear localization. ABRAXAS1 acts in the nuclear DNA damage response and localizes to DNA damage sites within the nucleus.
Reason: The UniProt record and the original BRCA1-A studies place ABRAXAS1 in the nucleus, where it recruits/organizes BRCA1-A complex activity at DNA double-strand breaks.
Supporting Evidence:
file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
Nucleus {ECO:0000269|PubMed:17525340, ECO:0000269|PubMed:17643121, ECO:0000269|PubMed:17643122}.
PMID:17525340
RAP80 was required for optimal accumulation of BRCA1 on damaged DNA (foci) in response to ionizing radiation
GO:0008017 microtubule binding
IBA
GO_REF:0000033
REMOVE
Summary: Likely paralog/family over-propagation. The IBA trace for this microtubule-binding term cites ABRAXAS2 rather than ABRAXAS1-specific evidence.
Reason: ABRAXAS1 literature, UniProt, Reactome, and PN context support a nuclear BRCA1-A DNA damage-response scaffold, not microtubule binding. No ABRAXAS1-specific microtubule-binding evidence was found in the cached evidence set.
Supporting Evidence:
file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
Involved in DNA damage response and double-strand break (DSB) repair.
file:human/ABRAXAS1/ABRAXAS1-notes.md
The IBA microtubule/spindle annotations are projected through a PANTHER node supported by ABRAXAS2
GO:0008608 attachment of spindle microtubules to kinetochore
IBA
GO_REF:0000033
REMOVE
Summary: Likely paralog/family over-propagation. The kinetochore-microtubule attachment IBA is not supported by ABRAXAS1-specific DNA damage literature.
Reason: The with/from metadata points to ABRAXAS2 for the spindle branch, while ABRAXAS1 evidence supports BRCA1-A complex-mediated DNA damage signaling. This process would overstate ABRAXAS1 biology.
Supporting Evidence:
file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
Involved in DNA damage response and double-strand break (DSB) repair.
file:human/ABRAXAS1/ABRAXAS1-notes.md
I marked `microtubule binding`, `attachment of spindle microtubules to kinetochore`, and `mitotic spindle assembly` for removal for ABRAXAS1.
GO:0031593 polyubiquitin modification-dependent protein binding
IBA
GO_REF:0000033
ACCEPT
Summary: Core molecular function. ABRAXAS1 is part of a BRCA1-A/RAP80 complex that recognizes ubiquitinated damage-site chromatin and has polyubiquitin-binding capacity.
Reason: The term captures the ubiquitin-recognition side of ABRAXAS1 biology better than generic protein binding. It should be retained for both direct IDA and IBA evidence.
Supporting Evidence:
PMID:19261749
four members of the BRCA1-A complex possess a polyubiquitin chain-binding capability
PMID:20656689
RAP80, in turn, is recruited to DSBs through its tandem ubiquitin-interacting motifs (UIMs) ( 6 , 14 – 16 ), which specifically recognize K63-Ub chains
GO:0090307 mitotic spindle assembly
IBA
GO_REF:0000033
REMOVE
Summary: Likely paralog/family over-propagation. The mitotic-spindle-assembly IBA is not supported for ABRAXAS1 by the reviewed evidence.
Reason: ABRAXAS1 participates in nuclear DNA damage repair/checkpoint signaling. The PANTHER IBA spindle call is traceable to ABRAXAS2 and should not be propagated to ABRAXAS1 without gene-specific evidence.
Supporting Evidence:
file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
Involved in DNA damage response and double-strand break (DSB) repair.
file:human/ABRAXAS1/ABRAXAS1-notes.md
I marked `microtubule binding`, `attachment of spindle microtubules to kinetochore`, and `mitotic spindle assembly` for removal for ABRAXAS1.
GO:0005634 nucleus
IEA
GO_REF:0000044
ACCEPT
Summary: Supported nuclear localization. ABRAXAS1 acts in the nuclear DNA damage response and localizes to DNA damage sites within the nucleus.
Reason: The UniProt record and the original BRCA1-A studies place ABRAXAS1 in the nucleus, where it recruits/organizes BRCA1-A complex activity at DNA double-strand breaks.
Supporting Evidence:
file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
Nucleus {ECO:0000269|PubMed:17525340, ECO:0000269|PubMed:17643121, ECO:0000269|PubMed:17643122}.
PMID:17525340
RAP80 was required for optimal accumulation of BRCA1 on damaged DNA (foci) in response to ionizing radiation
GO:0005515 protein binding
IPI
PMID:17525340
Abraxas and RAP80 form a BRCA1 protein complex required for ...
MARK AS OVER ANNOTATED
Summary: Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
Reason: These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome rows are even less suitable as function claims.
Supporting Evidence:
PMID:17525340
identified a protein, Abraxas, that directly binds the BRCA1 BRCT repeats
PMID:20656689
The RAP80 complex is a five-member stoichiometric complex consisting of RAP80, BRCC36, BRCC45, Abraxas, and MERIT40
GO:0005515 protein binding
IPI
PMID:17643121
CCDC98 targets BRCA1 to DNA damage sites.
MARK AS OVER ANNOTATED
Summary: Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
Reason: These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome rows are even less suitable as function claims.
Supporting Evidence:
PMID:17643121
CCDC98 is a BRCA1 binding partner that mediates BRCA1 function in response to DNA damage.
PMID:20656689
The RAP80 complex is a five-member stoichiometric complex consisting of RAP80, BRCC36, BRCC45, Abraxas, and MERIT40
GO:0005515 protein binding
IPI
PMID:18077395
Ubc13/Rnf8 ubiquitin ligases control foci formation of the R...
MARK AS OVER ANNOTATED
Summary: Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
Reason: These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome rows are even less suitable as function claims.
Supporting Evidence:
PMID:18077395
Rap80 contains an Abraxas interaction domain
PMID:20656689
The RAP80 complex is a five-member stoichiometric complex consisting of RAP80, BRCC36, BRCC45, Abraxas, and MERIT40
GO:0005515 protein binding
IPI
PMID:19615732
Defining the human deubiquitinating enzyme interaction lands...
MARK AS OVER ANNOTATED
Summary: Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
Reason: These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome rows are even less suitable as function claims.
Supporting Evidence:
PMID:19615732
We identified 774 candidate interacting proteins associated with 75 Dubs.
GO:0005515 protein binding
IPI
PMID:29656893
DNA Repair Network Analysis Reveals Shieldin as a Key Regula...
MARK AS OVER ANNOTATED
Summary: Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
Reason: These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome rows are even less suitable as function claims.
Supporting Evidence:
PMID:29656893
we generated high-resolution interaction neighborhood maps of the endogenously expressed DNA repair factors 53BP1, BRCA1, and MDC1
GO:0005515 protein binding
IPI
PMID:34591612
A protein interaction landscape of breast cancer.
MARK AS OVER ANNOTATED
Summary: Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
Reason: These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome rows are even less suitable as function claims.
Supporting Evidence:
PMID:34591612
we generated comprehensive interaction maps for 40 frequently altered BC proteins
GO:0005515 protein binding
IPI
PMID:35156780
CFTR interactome mapping using the mammalian membrane two-hy...
MARK AS OVER ANNOTATED
Summary: Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
Reason: These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome rows are even less suitable as function claims.
Supporting Evidence:
PMID:35156780
high-throughput screening variant of the Mammalian Membrane Two-Hybrid
GO:0005515 protein binding
IPI
PMID:36012204
Differential CFTR-Interactome Proximity Labeling Procedures ...
MARK AS OVER ANNOTATED
Summary: Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
Reason: These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome rows are even less suitable as function claims.
Supporting Evidence:
PMID:36012204
proximity labeling approaches identified both known and additional CFTR protein partners
GO:0005515 protein binding
IPI
PMID:39009827
Proteome-scale characterisation of motif-based interactome r...
MARK AS OVER ANNOTATED
Summary: Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
Reason: These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome rows are even less suitable as function claims.
Supporting Evidence:
PMID:39009827
we identified 366 mutation-modulated interactions
GO:0016604 nuclear body
IDA
GO_REF:0000052
KEEP AS NON CORE
Summary: Non-core localization. HPA reports nuclear-body staining, while mechanistic ABRAXAS1 biology centers on DNA damage foci/BRCA1-A complex recruitment.
Reason: This cellular component is plausible as a localization observation, but it is less informative than nucleus/nucleoplasm and BRCA1-A complex membership for the gene product function.
Supporting Evidence:
file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
Localizes at sites of DNA damage at double-strand breaks (DSBs).
GO:0005634 nucleus
NAS
PMID:20656689
Differential regulation of JAMM domain deubiquitinating enzy...
ACCEPT
Summary: Supported nuclear localization. ABRAXAS1 acts in the nuclear DNA damage response and localizes to DNA damage sites within the nucleus.
Reason: The UniProt record and the original BRCA1-A studies place ABRAXAS1 in the nucleus, where it recruits/organizes BRCA1-A complex activity at DNA double-strand breaks.
Supporting Evidence:
file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
Nucleus {ECO:0000269|PubMed:17525340, ECO:0000269|PubMed:17643121, ECO:0000269|PubMed:17643122}.
PMID:17525340
RAP80 was required for optimal accumulation of BRCA1 on damaged DNA (foci) in response to ionizing radiation
GO:0006282 regulation of DNA repair
NAS
PMID:20656689
Differential regulation of JAMM domain deubiquitinating enzy...
MODIFY
Summary: The broad regulation-of-DNA-repair annotation is directionally correct but less precise than positive regulation of DNA repair for ABRAXAS1.
Reason: ABRAXAS1 promotes BRCA1-A complex recruitment/stability and DNA repair after damage; the reviewed IMP annotations already use the more informative positive-regulation term.
Supporting Evidence:
PMID:17525340
Both Abraxas and RAP80 were required for DNA damage resistance, G(2)-M checkpoint control, and DNA repair.
PMID:19261748
a stable complex containing MERIT40 acts early in DNA damage response and regulates damage-dependent BRCA1 localization
GO:0044818 mitotic G2/M transition checkpoint
NAS
PMID:22369660
BRCA1 tumor suppressor network: focusing on its tail.
MODIFY
Summary: The ComplexPortal/NAS checkpoint annotation is real but should be represented using the more specific DNA-damage checkpoint signaling term.
Reason: ABRAXAS1 evidence concerns BRCA1-dependent G2/M checkpoint activation in response to DNA damage, not the generic mitotic G2/M transition checkpoint.
Supporting Evidence:
PMID:17643121
CCDC98 controls both DNA damage-induced formation of BRCA1 foci and BRCA1-dependent G2/M checkpoint activation
PMID:22369660
Studies on A, B and C complexes of BRCA1 indicate that these complexes carry out functions of BRCA1 in cell cycle checkpoint control.
GO:0070531 BRCA1-A complex
NAS
PMID:20656689
Differential regulation of JAMM domain deubiquitinating enzy...
ACCEPT
Summary: Core complex membership. ABRAXAS1 is a BRCA1-A complex subunit that organizes BRCA1, UIMC1/RAP80, BRCC3/BRCC36, BABAM proteins, and related DDR functions.
Reason: Multiple primary studies and Reactome support ABRAXAS1/FAM175A as a BRCA1-A complex component. This is more precise than the PN-projected generic ubiquitin-ligase-complex bucket.
Supporting Evidence:
PMID:19261749
Proteomic analysis revealed that NBA1 is a component of the BRCA1 A complex, which also contains Brca1/Bard1, Abra1, RAP80, BRCC36, and BRE.
Reactome:R-HSA-5683385
Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A complex at DNA DSBs
GO:0007095 mitotic G2 DNA damage checkpoint signaling
IMP
PMID:17525340
Abraxas and RAP80 form a BRCA1 protein complex required for ...
ACCEPT
Summary: Core checkpoint process. ABRAXAS1/CCDC98 is required for BRCA1-dependent G2/M checkpoint signaling after DNA damage.
Reason: The original ABRAXAS1/CCDC98 work and later BRCA1-A review evidence support a G2 DNA damage checkpoint role. This is part of the DNA damage response function rather than a general mitotic-spindle role.
Supporting Evidence:
PMID:17643121
CCDC98 controls both DNA damage-induced formation of BRCA1 foci and BRCA1-dependent G2/M checkpoint activation
PMID:22369660
Studies on A, B and C complexes of BRCA1 indicate that these complexes carry out functions of BRCA1 in cell cycle checkpoint control.
GO:0007095 mitotic G2 DNA damage checkpoint signaling
IMP
PMID:17643121
CCDC98 targets BRCA1 to DNA damage sites.
ACCEPT
Summary: Core checkpoint process. ABRAXAS1/CCDC98 is required for BRCA1-dependent G2/M checkpoint signaling after DNA damage.
Reason: The original ABRAXAS1/CCDC98 work and later BRCA1-A review evidence support a G2 DNA damage checkpoint role. This is part of the DNA damage response function rather than a general mitotic-spindle role.
Supporting Evidence:
PMID:17643121
CCDC98 controls both DNA damage-induced formation of BRCA1 foci and BRCA1-dependent G2/M checkpoint activation
PMID:22369660
Studies on A, B and C complexes of BRCA1 indicate that these complexes carry out functions of BRCA1 in cell cycle checkpoint control.
GO:0007095 mitotic G2 DNA damage checkpoint signaling
IMP
PMID:19261748
MERIT40 facilitates BRCA1 localization and DNA damage repair...
ACCEPT
Summary: Core checkpoint process. ABRAXAS1/CCDC98 is required for BRCA1-dependent G2/M checkpoint signaling after DNA damage.
Reason: The original ABRAXAS1/CCDC98 work and later BRCA1-A review evidence support a G2 DNA damage checkpoint role. This is part of the DNA damage response function rather than a general mitotic-spindle role.
Supporting Evidence:
PMID:17643121
CCDC98 controls both DNA damage-induced formation of BRCA1 foci and BRCA1-dependent G2/M checkpoint activation
PMID:22369660
Studies on A, B and C complexes of BRCA1 indicate that these complexes carry out functions of BRCA1 in cell cycle checkpoint control.
GO:0005654 nucleoplasm
TAS
Reactome:R-HSA-5683384
ACCEPT
Summary: Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1 are modeled at nuclear DNA double-strand breaks.
Reason: The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
Supporting Evidence:
Reactome:R-HSA-5683385
Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A complex at DNA DSBs
GO:0005654 nucleoplasm
TAS
Reactome:R-HSA-5683385
ACCEPT
Summary: Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1 are modeled at nuclear DNA double-strand breaks.
Reason: The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
Supporting Evidence:
Reactome:R-HSA-5683385
Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A complex at DNA DSBs
GO:0005654 nucleoplasm
TAS
Reactome:R-HSA-5683735
ACCEPT
Summary: Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1 are modeled at nuclear DNA double-strand breaks.
Reason: The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
Supporting Evidence:
Reactome:R-HSA-5683385
Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A complex at DNA DSBs
GO:0005654 nucleoplasm
TAS
Reactome:R-HSA-5683801
ACCEPT
Summary: Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1 are modeled at nuclear DNA double-strand breaks.
Reason: The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
Supporting Evidence:
Reactome:R-HSA-5683385
Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A complex at DNA DSBs
GO:0005654 nucleoplasm
TAS
Reactome:R-HSA-5684052
ACCEPT
Summary: Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1 are modeled at nuclear DNA double-strand breaks.
Reason: The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
Supporting Evidence:
Reactome:R-HSA-5683385
Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A complex at DNA DSBs
GO:0005654 nucleoplasm
TAS
Reactome:R-HSA-5684071
ACCEPT
Summary: Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1 are modeled at nuclear DNA double-strand breaks.
Reason: The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
Supporting Evidence:
Reactome:R-HSA-5683385
Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A complex at DNA DSBs
GO:0005654 nucleoplasm
TAS
Reactome:R-HSA-5686685
ACCEPT
Summary: Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1 are modeled at nuclear DNA double-strand breaks.
Reason: The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
Supporting Evidence:
Reactome:R-HSA-5683385
Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A complex at DNA DSBs
GO:0005654 nucleoplasm
TAS
Reactome:R-HSA-5691411
ACCEPT
Summary: Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1 are modeled at nuclear DNA double-strand breaks.
Reason: The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
Supporting Evidence:
Reactome:R-HSA-5683385
Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A complex at DNA DSBs
GO:0005654 nucleoplasm
TAS
Reactome:R-HSA-5693551
ACCEPT
Summary: Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1 are modeled at nuclear DNA double-strand breaks.
Reason: The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
Supporting Evidence:
Reactome:R-HSA-5683385
Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A complex at DNA DSBs
GO:0005654 nucleoplasm
TAS
Reactome:R-HSA-69891
ACCEPT
Summary: Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1 are modeled at nuclear DNA double-strand breaks.
Reason: The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
Supporting Evidence:
Reactome:R-HSA-5683385
Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A complex at DNA DSBs
GO:0005515 protein binding
IPI
PMID:19261748
MERIT40 facilitates BRCA1 localization and DNA damage repair...
MARK AS OVER ANNOTATED
Summary: Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
Reason: These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome rows are even less suitable as function claims.
Supporting Evidence:
PMID:19261748
CCDC98 binds to RAP80 via a large N-terminal region
PMID:20656689
The RAP80 complex is a five-member stoichiometric complex consisting of RAP80, BRCC36, BRCC45, Abraxas, and MERIT40
GO:0005515 protein binding
IPI
PMID:19261749
NBA1, a new player in the Brca1 A complex, is required for D...
MARK AS OVER ANNOTATED
Summary: Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
Reason: These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome rows are even less suitable as function claims.
Supporting Evidence:
PMID:19261749
four members of the BRCA1-A complex possess a polyubiquitin chain-binding capability
PMID:20656689
The RAP80 complex is a five-member stoichiometric complex consisting of RAP80, BRCC36, BRCC45, Abraxas, and MERIT40
GO:0005634 nucleus
IDA
PMID:17525340
Abraxas and RAP80 form a BRCA1 protein complex required for ...
ACCEPT
Summary: Supported nuclear localization. ABRAXAS1 acts in the nuclear DNA damage response and localizes to DNA damage sites within the nucleus.
Reason: The UniProt record and the original BRCA1-A studies place ABRAXAS1 in the nucleus, where it recruits/organizes BRCA1-A complex activity at DNA double-strand breaks.
Supporting Evidence:
file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
Nucleus {ECO:0000269|PubMed:17525340, ECO:0000269|PubMed:17643121, ECO:0000269|PubMed:17643122}.
PMID:17525340
RAP80 was required for optimal accumulation of BRCA1 on damaged DNA (foci) in response to ionizing radiation
GO:0005634 nucleus
IDA
PMID:17643121
CCDC98 targets BRCA1 to DNA damage sites.
ACCEPT
Summary: Supported nuclear localization. ABRAXAS1 acts in the nuclear DNA damage response and localizes to DNA damage sites within the nucleus.
Reason: The UniProt record and the original BRCA1-A studies place ABRAXAS1 in the nucleus, where it recruits/organizes BRCA1-A complex activity at DNA double-strand breaks.
Supporting Evidence:
file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
Nucleus {ECO:0000269|PubMed:17525340, ECO:0000269|PubMed:17643121, ECO:0000269|PubMed:17643122}.
PMID:17525340
RAP80 was required for optimal accumulation of BRCA1 on damaged DNA (foci) in response to ionizing radiation
GO:0006302 double-strand break repair
IMP
PMID:17525340
Abraxas and RAP80 form a BRCA1 protein complex required for ...
ACCEPT
Summary: Core biological process. ABRAXAS1 is required for efficient DNA double-strand break repair through BRCA1-A recruitment and ubiquitin-dependent damage-site signaling.
Reason: Loss/depletion experiments in the original ABRAXAS1/CCDC98 papers support DNA repair and DNA damage resistance. The PN-projected broader DNA repair term is already entailed by this annotation.
Supporting Evidence:
PMID:17525340
Both Abraxas and RAP80 were required for DNA damage resistance, G(2)-M checkpoint control, and DNA repair.
PMID:19261748
a stable complex containing MERIT40 acts early in DNA damage response and regulates damage-dependent BRCA1 localization
GO:0006302 double-strand break repair
IMP
PMID:17643121
CCDC98 targets BRCA1 to DNA damage sites.
ACCEPT
Summary: Core biological process. ABRAXAS1 is required for efficient DNA double-strand break repair through BRCA1-A recruitment and ubiquitin-dependent damage-site signaling.
Reason: Loss/depletion experiments in the original ABRAXAS1/CCDC98 papers support DNA repair and DNA damage resistance. The PN-projected broader DNA repair term is already entailed by this annotation.
Supporting Evidence:
PMID:17525340
Both Abraxas and RAP80 were required for DNA damage resistance, G(2)-M checkpoint control, and DNA repair.
PMID:19261748
a stable complex containing MERIT40 acts early in DNA damage response and regulates damage-dependent BRCA1 localization
GO:0006302 double-strand break repair
IMP
PMID:19261748
MERIT40 facilitates BRCA1 localization and DNA damage repair...
ACCEPT
Summary: Core biological process. ABRAXAS1 is required for efficient DNA double-strand break repair through BRCA1-A recruitment and ubiquitin-dependent damage-site signaling.
Reason: Loss/depletion experiments in the original ABRAXAS1/CCDC98 papers support DNA repair and DNA damage resistance. The PN-projected broader DNA repair term is already entailed by this annotation.
Supporting Evidence:
PMID:17525340
Both Abraxas and RAP80 were required for DNA damage resistance, G(2)-M checkpoint control, and DNA repair.
PMID:19261748
a stable complex containing MERIT40 acts early in DNA damage response and regulates damage-dependent BRCA1 localization
GO:0010212 response to ionizing radiation
IMP
PMID:17525340
Abraxas and RAP80 form a BRCA1 protein complex required for ...
KEEP AS NON CORE
Summary: Supported but non-core phenotype/context annotation. Ionizing radiation is the experimental damage stimulus used to reveal ABRAXAS1 DNA damage-response function.
Reason: The IR response annotations should be retained as useful experimental context, but the core process is DNA double-strand break repair/checkpoint signaling through BRCA1-A.
Supporting Evidence:
PMID:18077395
the entire Brca1 A complex to DNA-damage foci
PMID:19261749
required for resistance to ionizing radiation
GO:0010212 response to ionizing radiation
IMP
PMID:17643121
CCDC98 targets BRCA1 to DNA damage sites.
KEEP AS NON CORE
Summary: Supported but non-core phenotype/context annotation. Ionizing radiation is the experimental damage stimulus used to reveal ABRAXAS1 DNA damage-response function.
Reason: The IR response annotations should be retained as useful experimental context, but the core process is DNA double-strand break repair/checkpoint signaling through BRCA1-A.
Supporting Evidence:
PMID:18077395
the entire Brca1 A complex to DNA-damage foci
PMID:19261749
required for resistance to ionizing radiation
GO:0010212 response to ionizing radiation
IMP
PMID:19261748
MERIT40 facilitates BRCA1 localization and DNA damage repair...
KEEP AS NON CORE
Summary: Supported but non-core phenotype/context annotation. Ionizing radiation is the experimental damage stimulus used to reveal ABRAXAS1 DNA damage-response function.
Reason: The IR response annotations should be retained as useful experimental context, but the core process is DNA double-strand break repair/checkpoint signaling through BRCA1-A.
Supporting Evidence:
PMID:18077395
the entire Brca1 A complex to DNA-damage foci
PMID:19261749
required for resistance to ionizing radiation
GO:0031593 polyubiquitin modification-dependent protein binding
IDA
PMID:19261749
NBA1, a new player in the Brca1 A complex, is required for D...
ACCEPT
Summary: Core molecular function. ABRAXAS1 is part of a BRCA1-A/RAP80 complex that recognizes ubiquitinated damage-site chromatin and has polyubiquitin-binding capacity.
Reason: The term captures the ubiquitin-recognition side of ABRAXAS1 biology better than generic protein binding. It should be retained for both direct IDA and IBA evidence.
Supporting Evidence:
PMID:19261749
four members of the BRCA1-A complex possess a polyubiquitin chain-binding capability
PMID:20656689
RAP80, in turn, is recruited to DSBs through its tandem ubiquitin-interacting motifs (UIMs) ( 6 , 14 – 16 ), which specifically recognize K63-Ub chains
GO:0045739 positive regulation of DNA repair
IMP
PMID:17525340
Abraxas and RAP80 form a BRCA1 protein complex required for ...
ACCEPT
Summary: Core regulatory process. ABRAXAS1 positively supports DNA repair by assembling/stabilizing the RAP80-BRCA1-A complex at DNA damage sites.
Reason: The evidence supports a positive role in DNA repair through BRCA1 localization, complex integrity, and BRCC36-associated ubiquitin editing rather than direct DNA repair catalysis.
Supporting Evidence:
PMID:17525340
Both Abraxas and RAP80 were required for DNA damage resistance, G(2)-M checkpoint control, and DNA repair.
PMID:19261748
a stable complex containing MERIT40 acts early in DNA damage response and regulates damage-dependent BRCA1 localization
PMID:20656689
Abraxas and BRCC45 were essential for BRCC36 DUB activity within the RAP80 complex
GO:0045739 positive regulation of DNA repair
IMP
PMID:19261748
MERIT40 facilitates BRCA1 localization and DNA damage repair...
ACCEPT
Summary: Core regulatory process. ABRAXAS1 positively supports DNA repair by assembling/stabilizing the RAP80-BRCA1-A complex at DNA damage sites.
Reason: The evidence supports a positive role in DNA repair through BRCA1 localization, complex integrity, and BRCC36-associated ubiquitin editing rather than direct DNA repair catalysis.
Supporting Evidence:
PMID:17525340
Both Abraxas and RAP80 were required for DNA damage resistance, G(2)-M checkpoint control, and DNA repair.
PMID:19261748
a stable complex containing MERIT40 acts early in DNA damage response and regulates damage-dependent BRCA1 localization
PMID:20656689
Abraxas and BRCC45 were essential for BRCC36 DUB activity within the RAP80 complex
GO:0070531 BRCA1-A complex
IDA
PMID:17525340
Abraxas and RAP80 form a BRCA1 protein complex required for ...
ACCEPT
Summary: Core complex membership. ABRAXAS1 is a BRCA1-A complex subunit that organizes BRCA1, UIMC1/RAP80, BRCC3/BRCC36, BABAM proteins, and related DDR functions.
Reason: Multiple primary studies and Reactome support ABRAXAS1/FAM175A as a BRCA1-A complex component. This is more precise than the PN-projected generic ubiquitin-ligase-complex bucket.
Supporting Evidence:
PMID:19261749
Proteomic analysis revealed that NBA1 is a component of the BRCA1 A complex, which also contains Brca1/Bard1, Abra1, RAP80, BRCC36, and BRE.
Reactome:R-HSA-5683385
Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A complex at DNA DSBs
GO:0070531 BRCA1-A complex
IDA
PMID:19261746
MERIT40 controls BRCA1-Rap80 complex integrity and recruitme...
ACCEPT
Summary: Core complex membership. ABRAXAS1 is a BRCA1-A complex subunit that organizes BRCA1, UIMC1/RAP80, BRCC3/BRCC36, BABAM proteins, and related DDR functions.
Reason: Multiple primary studies and Reactome support ABRAXAS1/FAM175A as a BRCA1-A complex component. This is more precise than the PN-projected generic ubiquitin-ligase-complex bucket.
Supporting Evidence:
PMID:19261749
Proteomic analysis revealed that NBA1 is a component of the BRCA1 A complex, which also contains Brca1/Bard1, Abra1, RAP80, BRCC36, and BRE.
Reactome:R-HSA-5683385
Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A complex at DNA DSBs
GO:0070531 BRCA1-A complex
IDA
PMID:19261748
MERIT40 facilitates BRCA1 localization and DNA damage repair...
ACCEPT
Summary: Core complex membership. ABRAXAS1 is a BRCA1-A complex subunit that organizes BRCA1, UIMC1/RAP80, BRCC3/BRCC36, BABAM proteins, and related DDR functions.
Reason: Multiple primary studies and Reactome support ABRAXAS1/FAM175A as a BRCA1-A complex component. This is more precise than the PN-projected generic ubiquitin-ligase-complex bucket.
Supporting Evidence:
PMID:19261749
Proteomic analysis revealed that NBA1 is a component of the BRCA1 A complex, which also contains Brca1/Bard1, Abra1, RAP80, BRCC36, and BRE.
Reactome:R-HSA-5683385
Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A complex at DNA DSBs
GO:0070531 BRCA1-A complex
IDA
PMID:19261749
NBA1, a new player in the Brca1 A complex, is required for D...
ACCEPT
Summary: Core complex membership. ABRAXAS1 is a BRCA1-A complex subunit that organizes BRCA1, UIMC1/RAP80, BRCC3/BRCC36, BABAM proteins, and related DDR functions.
Reason: Multiple primary studies and Reactome support ABRAXAS1/FAM175A as a BRCA1-A complex component. This is more precise than the PN-projected generic ubiquitin-ligase-complex bucket.
Supporting Evidence:
PMID:19261749
Proteomic analysis revealed that NBA1 is a component of the BRCA1 A complex, which also contains Brca1/Bard1, Abra1, RAP80, BRCC36, and BRE.
Reactome:R-HSA-5683385
Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A complex at DNA DSBs

Core Functions

ABRAXAS1 is a scaffold and ubiquitin-recognition subunit of the nuclear BRCA1-A/RAP80 complex. It helps assemble BRCA1, UIMC1/RAP80, BRCC3/BRCC36, BABAM proteins, and related partners at ubiquitinated DNA double-strand break sites, thereby supporting BRCA1 recruitment, BRCC36-dependent K63-ubiquitin signal editing, DNA repair, and G2/M DNA damage checkpoint signaling.

Supporting Evidence:
  • PMID:17525340
    Abraxas and RAP80 were required for DNA damage resistance, G(2)-M checkpoint control, and DNA repair.
  • PMID:19261748
    CCDC98 as the central component that facilitates the assembly of this protein complex
  • PMID:19261749
    four members of the BRCA1-A complex possess a polyubiquitin chain-binding capability
  • PMID:20656689
    Abraxas and BRCC45 were essential for BRCC36 DUB activity within the RAP80 complex
  • Reactome:R-HSA-5683385
    Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A complex at DNA DSBs
  • file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
    Involved in DNA damage response and double-strand break (DSB) repair.

References

Annotation inferences using phylogenetic trees
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
Gene Ontology annotation based on curation of immunofluorescence data
Abraxas and RAP80 form a BRCA1 protein complex required for the DNA damage response.
  • ABRAXAS1/Abraxas binds BRCA1 BRCT repeats and RAP80, and is required for DNA damage resistance, G2/M checkpoint control, and DNA repair.
    "Abraxas and RAP80 were required for DNA damage resistance, G(2)-M checkpoint control, and DNA repair."
CCDC98 targets BRCA1 to DNA damage sites.
Ubc13/Rnf8 ubiquitin ligases control foci formation of the Rap80/Abraxas/Brca1/Brcc36 complex in response to DNA damage.
MERIT40 controls BRCA1-Rap80 complex integrity and recruitment to DNA double-strand breaks.
MERIT40 facilitates BRCA1 localization and DNA damage repair.
  • CCDC98/ABRAXAS1 is a central component for assembly of the RAP80-containing BRCA1-A complex at DNA damage sites.
    "CCDC98 as the central component that facilitates the assembly of this protein complex"
NBA1, a new player in the Brca1 A complex, is required for DNA damage resistance and checkpoint control.
Defining the human deubiquitinating enzyme interaction landscape.
Differential regulation of JAMM domain deubiquitinating enzyme activity within the RAP80 complex.
  • ABRAXAS1 is required for BRCC36 DUB activity in the RAP80/BRCA1-A complex context, but is not itself the catalytic DUB.
    "Abraxas and BRCC45 were essential for BRCC36 DUB activity within the RAP80 complex"
BRCA1 tumor suppressor network: focusing on its tail.
DNA Repair Network Analysis Reveals Shieldin as a Key Regulator of NHEJ and PARP Inhibitor Sensitivity.
A protein interaction landscape of breast cancer.
CFTR interactome mapping using the mammalian membrane two-hybrid high-throughput screening system.
Differential CFTR-Interactome Proximity Labeling Procedures Identify Enrichment in Multiple SLC Transporters.
Proteome-scale characterisation of motif-based interactome rewiring by disease mutations.
  • ABRAXAS1 contains a functional nuclear localization signal around Arg361; the breast-cancer-associated R361Q mutation weakens importin/karyopherin binding approximately tenfold and increases cytoplasmic localization, providing a molecular basis for impaired nuclear import of the BRCA1-A complex.
Reactome:R-HSA-5683384
UIMC1 and FAM175A bind DNA DSBs
Reactome:R-HSA-5683385
Formation of BRCA1-A complex at DNA DSBs
Reactome:R-HSA-5683735
CHEK2 is recruited to DNA DSBs
Reactome:R-HSA-5683801
CHEK2 phosphorylates BRCA1
Reactome:R-HSA-5684052
PIAS4 SUMOylates MDC1
Reactome:R-HSA-5684071
RNF4 ubiquitinates MDC1
Reactome:R-HSA-5686685
RIF1 and PAX1IP bind TP53BP1 at DNA DSBs
Reactome:R-HSA-5691411
BRCA1-A complex deubiquitinates K63polyUb-histone H2A
Reactome:R-HSA-5693551
Phosphorylation of BRCA1-A complex at multiple sites by ATM
Reactome:R-HSA-69891
Phosphorylation and activation of CHEK2 by ATM
file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
ABRAXAS1 UniProtKB record
file:human/ABRAXAS1/ABRAXAS1-notes.md
ABRAXAS1 manual review notes and failed deep-research provenance
file:projects/PROTEOSTASIS/reports/pn_projection/pn_projected_gene_go_summary.tsv
Proteostasis PN projected GO summary for ABRAXAS1
file:projects/PROTEOSTASIS/mappings/ubiquitin_proteasome_system.yaml
Proteostasis ubiquitin proteasome system mapping file
file:interpro/panther/PTHR31728/PTHR31728-entries.csv
PANTHER PTHR31728 reviewed protein members

Suggested Questions for Experts

Q: Should GO curation represent ABRAXAS1 only as part of the BRCA1-A complex, or is there enough evidence to annotate ABRAXAS1 to a broader ubiquitin ligase complex term despite its scaffold/DUB-support role?

Suggested experts: Wang B, Greenberg RA, Elledge SJ

Q: Given evidence that ABRAXAS1 truncations shift BRCA1 partitioning toward BRCA1-C and derepress mutagenic repair (SSA/MMEJ) without impairing HR, should ABRAXAS1 carry a negative-regulation annotation for low-fidelity double-strand break repair pathways (e.g. single-strand annealing) in addition to its positive role in DNA repair?

Suggested experts: Wiesmuller L, Pylkas K

Q: Is the reported RNA-dependent / direct RNA-binding behavior of ABRAXAS1 (R-DeeP and iCLIP2 in a single lung-cancer cell line) reproducible and functionally meaningful, or a cell-line-specific high-throughput artifact, before any RNA-binding annotation is considered?

Suggested experts: Diederichs S

Suggested Experiments

Experiment: Compare ABRAXAS1 and ABRAXAS2 depletion or rescue in synchronized human cells using spindle assembly, kinetochore-microtubule attachment, and DNA damage-response readouts in the same experimental system.

Hypothesis: The PANTHER-derived spindle and microtubule annotations are ABRAXAS2/paralog-specific and do not apply to ABRAXAS1.

Type: comparative cell biology

Experiment: Use chromosomally integrated DSB-repair reporters (HR, NHEJ, MMEJ, SSA) in cells expressing wild-type ABRAXAS1 versus C-terminal SPTF-motif and BRCC36-interaction truncation variants, measuring pathway-frequency shifts and end-resection markers (RPA, pRPA32, MRE11) to test pathway-choice control.

Hypothesis: ABRAXAS1 restrains end resection and mutagenic double-strand break repair (single-strand annealing / microhomology-mediated end joining) by sequestering BRCA1 in the BRCA1-A complex, rather than simply promoting homologous recombination.

Type: DSB-repair pathway reporter assay

Deep Research

Falcon

(ABRAXAS1-deep-research-falcon.md)
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate. Falcon Edison Scientific Literature 30 citations 2 artifacts 2026-06-07T04:19:46.593250

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: ABRAXAS1 (UniProt Q6UWZ7; human)

0) Gene/protein identity verification (mandatory)

ABRAXAS1 (UniProt Q6UWZ7) is the human protein also known as ABRA1/CCDC98/FAM175A and is the BRCA1-A complex subunit Abraxas 1. Multiple independent sources explicitly match these synonyms and the expected size (~409 aa) and functional motifs/domains (MPN-like N-terminus, NLS around residues 358–361, and C-terminal phospho-SPxF/“SPTF” BRCT-binding motif), confirming the correct target and distinguishing it from its paralog ABRO1/Abraxas2 (which specifies BRISC rather than BRCA1-A). (julius2020brca1aandbrisc pages 1-3, bose2019brca1mislocalizationleads pages 1-3, julius2020brca1aandbrisc pages 3-6)

Feature Molecular detail (residues/motif where available) Functional consequence Key sources (citation IDs) URL (if available)
Verified identity Human ABRAXAS1 / ABRA1 / CCDC98 / FAM175A; UniProt Q6UWZ7; ~409 aa scaffold/adaptor Confirms the target is the BRCA1-A complex subunit Abraxas 1, not the paralog ABRO1/Abraxas2 (julius2020brca1aandbrisc pages 1-3, bose2019brca1mislocalizationleads pages 1-3) https://doi.org/10.3390/biom10111503; https://doi.org/10.1093/hmg/ddz252
N-terminal MPN-like domain JAMM/MPN− domain; aa ~11–121; catalytically inactive due to loss of Zn-binding catalytic configuration Binds and activates the catalytic MPN+ DUB BRCC36; scaffold role rather than protease activity (julius2020brca1aandbrisc pages 3-6, kyrieleis2016threedimensionalarchitectureof pages 3-4) https://doi.org/10.3390/biom10111503; https://doi.org/10.1016/j.celrep.2016.11.063
Coiled-coil region aa ~206–260 Supports higher-order assembly/dimerization and contributes to interactions within BRCA1-A; loss with deeper truncation derepresses mutagenic DSBR pathways (julius2020brca1aandbrisc pages 3-6, sachsenweger2023abraxas1orchestratesbrca1 pages 1-2, sachsenweger2023abraxas1orchestratesbrca1 pages 8-9) https://doi.org/10.3390/biom10111503; https://doi.org/10.1038/s41419-023-05845-6
Nuclear localization signal (NLS) aa ~358–361; includes Arg361 Required for nuclear import of ABRAXAS1/BRCA1-A; R361Q impairs nuclear localization and BRCA1 focus formation (julius2020brca1aandbrisc pages 3-6, bose2019brca1mislocalizationleads pages 1-3, kliche2024proteomescalecharacterisationof pages 11-13) https://doi.org/10.3390/biom10111503; https://doi.org/10.1093/hmg/ddz252; https://doi.org/10.1038/s44320-024-00055-4
C-terminal BRCA1-binding motif pSPxF / SPTF motif at aa ~406–409; S404 damage-inducible, S406 constitutive, terminal F409 critical Phospho-dependent binding to BRCA1 BRCT domains; drives BRCA1 recruitment/sequestration in BRCA1-A (julius2020brca1aandbrisc pages 11-13, bose2019brca1mislocalizationleads pages 1-3, sachsenweger2023abraxas1orchestratesbrca1 pages 12-13) https://doi.org/10.3390/biom10111503; https://doi.org/10.1093/hmg/ddz252; https://doi.org/10.1038/s41419-023-05845-6
BRCC36 interaction N-terminal scaffold interaction via MPN dimer with BRCC36 Activates the K63-specific BRCC36 deubiquitinase and organizes the DUB core (julius2020brca1aandbrisc pages 3-6, julius2020brca1aandbrisc pages 8-11, kyrieleis2016threedimensionalarchitectureof pages 1-3) https://doi.org/10.3390/biom10111503; https://doi.org/10.1016/j.celrep.2016.11.063
RAP80 integration ABRAXAS1 C-terminal/unstructured region binds on top of RAP80; RAP80 is constitutive BRCA1-A subunit Couples BRCA1-A to K63-Ub and SUMO-ubiquitin damage marks at DSB-flanking chromatin (julius2020brca1aandbrisc pages 3-6, julius2019structuralbasisof pages 10-12) https://doi.org/10.3390/biom10111503; https://doi.org/10.1016/j.molcel.2019.06.002
BRCA1-A complex membership Core complex: ABRAXAS1, BRCC36, BRE/BRCC45, MERIT40, RAP80; BRCA1 binds via ABRAXAS1 phospho-tail Recruits/positions BRCA1-A at DNA damage foci, edits K63-Ub chromatin signals, limits end resection and suppresses excessive HR/SSA (julius2020brca1aandbrisc pages 1-3, julius2019structuralbasisof pages 10-12, sachsenweger2023abraxas1orchestratesbrca1 pages 1-2) https://doi.org/10.3390/biom10111503; https://doi.org/10.1016/j.molcel.2019.06.002; https://doi.org/10.1038/s41419-023-05845-6
BRISC distinction ABRAXAS1 is not the BRISC-specific adaptor; ABRO1/Abraxas2 replaces ABRAXAS1 in BRISC Explains why ABRAXAS1 is primarily linked to nuclear DNA-damage signaling, whereas BRISC has mostly non-nuclear/immune roles (julius2020brca1aandbrisc pages 1-3, julius2019structuralbasisof pages 1-3) https://doi.org/10.3390/biom10111503; https://doi.org/10.1016/j.molcel.2019.06.002
Cellular localization Predominantly nuclear; nuclear import depends on ABRAXAS1 NLS; BRCA1-A accumulates at DNA repair foci Ensures BRCA1-A function at chromatin near DSBs; defective localization perturbs DDR and checkpoint control (julius2020brca1aandbrisc pages 3-6, julius2019structuralbasisof pages 1-3, bose2019brca1mislocalizationleads pages 1-3) https://doi.org/10.3390/biom10111503; https://doi.org/10.1016/j.molcel.2019.06.002; https://doi.org/10.1093/hmg/ddz252
Structural architecture BRCA1-A core forms a V-shaped superdimer/dimer-of-heterotetramers with ABRAXAS1-BRCC36 at the base and BRCC45/MERIT40 in the arms Supports stable assembly, substrate engagement, and efficient K63-linked ubiquitin-chain processing (kyrieleis2016threedimensionalarchitectureof pages 5-6, kyrieleis2016threedimensionalarchitectureof pages 1-3) https://doi.org/10.1016/j.celrep.2016.11.063
DUB pathway function BRCC36 active site is K63-linkage specific; ABRAXAS1 acts as DEUBAD-like adaptor and targeting subunit Places K63-specific deubiquitination on chromatin at DNA breaks; helps delimit ubiquitin signaling domains around lesions (julius2020brca1aandbrisc pages 3-6, julius2020brca1aandbrisc pages 8-11, julius2020brca1aandbrisc pages 1-3) https://doi.org/10.3390/biom10111503
Patient-relevant truncation variants c.1106dup (p.Ser370Ilefs2) loses C-terminal BRCA1-binding motif; c.577C>T (p.Arg193) also lacks BRCC36-interaction region Shift BRCA1 partitioning from BRCA1-A toward BRCA1-C, increase SSA/MMEJ/NHEJ-associated phenotypes, and destabilize genome maintenance (sachsenweger2023abraxas1orchestratesbrca1 pages 3-6, sachsenweger2023abraxas1orchestratesbrca1 pages 8-9, sachsenweger2023abraxas1orchestratesbrca1 media db056916) https://doi.org/10.1038/s41419-023-05845-6
RNA-dependent / RNA-binding evidence Identified as RNA-dependent protein in A549 cells; direct RNA interaction validated by iCLIP2 Suggests an additional context-dependent RNA-associated behavior beyond canonical BRCA1-A scaffolding (rajagopal2022proteomewideidentificationof pages 1-2, rajagopal2022proteomewideidentificationof pages 5-7) https://doi.org/10.3390/cancers14246109

Table: This table compacts the key domain architecture, binding partners, complex membership, and localization features of human ABRAXAS1 (Q6UWZ7). It is useful as a quick-reference map linking specific motifs and residues to experimentally supported functions and recent disease-relevant findings.

1) Key concepts, definitions, and current understanding

1.1 ABRAXAS1 as a BRCA1-A scaffold/adaptor (not an enzyme)

ABRAXAS1 is best understood as a non-catalytic scaffold/adaptor subunit that organizes and targets the BRCA1-A deubiquitinase (DUB) complex to DNA damage–marked chromatin. In BRCA1-A, ABRAXAS1 assembles with BRCC36 (also called BRCC3), BRE/BRCC45, MERIT40, and RAP80, and then binds BRCA1 via a phospho-dependent interaction between the ABRAXAS1 C-terminus and the BRCA1 BRCT domains. (julius2020brca1aandbrisc pages 1-3, julius2019structuralbasisof pages 10-12, sachsenweger2023abraxas1orchestratesbrca1 pages 1-2)

ABRAXAS1 contains an N-terminal JAMM/MPN-like domain that is catalytically inactive (“MPN−”) and functions as an activator/scaffold for the catalytically active JAMM/MPN+ metalloprotease BRCC36. This is a central definitional point: ABRAXAS1 itself does not catalyze deubiquitination; instead it allosterically activates and positions BRCC36 within a multi-protein machine. (julius2020brca1aandbrisc pages 3-6, kyrieleis2016threedimensionalarchitectureof pages 3-4)

1.2 BRCA1-A vs BRISC: paralog-driven specialization

A key organizing concept in the field is that BRCC36 forms the enzymatic core of two distinct assemblies: (i) BRCA1-A (nuclear, DNA damage–associated) and (ii) BRISC (largely non-nuclear, immune/other signaling contexts). ABRAXAS1 and its paralog ABRO1 partition the shared BRCC36/BRE/MERIT40 core into BRCA1-A versus BRISC, respectively, thus providing targeting and regulatory specialization without changing the catalytic subunit. (julius2020brca1aandbrisc pages 1-3, julius2019structuralbasisof pages 1-3)

1.3 DNA damage recruitment logic and the role of ABRAXAS1 motifs

At DNA double-strand breaks (DSBs), upstream signaling generates K63-linked ubiquitin chains on chromatin (e.g., via RNF8/RNF168 pathway), which are recognized by RAP80 and thereby recruit BRCA1-A to DNA damage foci. ABRAXAS1 is central in this architecture because it integrates RAP80 into BRCA1-A and provides the phosphorylated BRCA1-binding tail. (bose2019brca1mislocalizationleads pages 1-3, julius2019structuralbasisof pages 10-12)

Mechanistically, ABRAXAS1 has:
- A nuclear localization signal (NLS; ~aa 358–361) required for nuclear localization of the BRCA1-A–BRCA1 assembly. (julius2020brca1aandbrisc pages 3-6, bose2019brca1mislocalizationleads pages 1-3)
- A C-terminal phospho-motif (commonly described as pSPxF/SPTF; ~aa 406–409) with phosphorylation sites including S404 (damage-inducible) and S406 (constitutive) that is recognized by BRCA1 BRCT domains, enabling phospho-dependent recruitment/sequestration. (julius2020brca1aandbrisc pages 11-13, bose2019brca1mislocalizationleads pages 1-3)

1.4 BRCA1 sequestration and pathway choice (conceptual model)

Structural and mechanistic work emphasizes that BRCA1-A can sequester BRCA1 in a high-affinity complex via ABRAXAS1’s BRCT-binding phospho-tail, and that BRCA1-A localization to DSB-flanking regions can limit end resection and thereby suppress homologous recombination (HR) under some contexts—conceptually positioning BRCA1-A as a “fine-tuner” of BRCA1 activities and repair pathway choice rather than a simple HR-promoting factor. (julius2020brca1aandbrisc pages 1-3, julius2019structuralbasisof pages 10-12)

2) Molecular function and mechanism: structural/biochemical evidence

2.1 Architecture of the BRCA1-A DUB core and ABRAXAS1’s role

Negative-stain EM of a reconstituted human BRCA1-A core complex (Abraxas/BRCC36/BRCC45/MERIT40) supports a V-shaped “superdimer” (dimer of heterotetramers) architecture, with ABRAXAS1/BRCC36 at the base and BRCC45/MERIT40 in the arms. This architecture explains how a scaffold like ABRAXAS1 contributes to stable assembly and productive substrate engagement. (kyrieleis2016threedimensionalarchitectureof pages 1-3, kyrieleis2016threedimensionalarchitectureof pages 5-6)

2.2 Activation and specificity of BRCC36: ABRAXAS1 as a DEUBAD-like adaptor

BRCC36 is a Zn2+-dependent JAMM/MPN metalloprotease and exhibits strict K63-linkage specificity, while ABRAXAS1 (MPN−) acts as a DEUBAD-like adaptor to activate BRCC36 upon assembly. A mechanistic model described in the BRCA1-A/BRISC review proposes that BRCC36 is inactive in isolation (E-loop disorder) and is activated by dimerization with ABRAXAS1 (or ABRO1 in BRISC), which helps position catalytic elements and enables substrate processing. (julius2020brca1aandbrisc pages 8-11, julius2020brca1aandbrisc pages 3-6)

The same review describes additional selectivity features: assembled complexes can show preference for longer K63 chains (≥4 ubiquitins), potentially via accessory ubiquitin-recognition subunits (e.g., BRE and MERIT40), and RAP80 can enhance targeting to mixed SUMO–K63 chains at DNA breaks—helping rationalize context-dependent substrate selection. (julius2020brca1aandbrisc pages 8-11)

2.3 BRCA1 binding avidity and incompatibility with other BRCT partners

Structural work further emphasizes that BRCA1 BRCT binding to an ABRAXAS1 phospho-peptide is mutually incompatible with BRCT interactions with other partners (e.g., CtIP, BACH1), and that the assembled BRCA1-A architecture produces high avidity (nanomolar-range) BRCA1 association. This provides a mechanistic basis for how ABRAXAS1-containing BRCA1-A can restrain BRCA1’s pro-resection activities at breaks. (julius2019structuralbasisof pages 10-12, julius2020brca1aandbrisc pages 11-13)

3) Cellular localization

BRCA1-A is described as predominantly nuclear, with ABRAXAS1 providing a nuclear import signal required for nuclear localization of the BRCA1-A–BRCA1 assembly. Disruption of this localization (e.g., NLS variants) leads to reduced BRCA1 nuclear localization and foci formation in patient-derived cells. (julius2020brca1aandbrisc pages 3-6, julius2019structuralbasisof pages 1-3, bose2019brca1mislocalizationleads pages 1-3)

4) Recent developments (prioritizing 2023–2024)

4.1 2023: patient-derived mechanistic genetics—truncations rewire BRCA1 complexes and DSBR pathway balance

A 2023 Cell Death & Disease study identified and functionally dissected two truncating germline ABRAXAS1 variants from early-onset breast cancer patients: c.1106dup (p.Ser370Ilefs2) removing the C-terminal BRCA1-binding SPTF motif, and c.577C>T (p.Arg193) additionally lacking the BRCC36-interaction region while retaining interaction sites for RAP80/MERIT40/BRCC45. (sachsenweger2023abraxas1orchestratesbrca1 pages 3-6, sachsenweger2023abraxas1orchestratesbrca1 pages 8-9)

Key quantitative findings included:
- Mono-allelic ABRAXAS1 mutation did not impair HR proficiency but de-repressed mutagenic pathways such as single-strand annealing (SSA). (sachsenweger2023abraxas1orchestratesbrca1 pages 3-6, sachsenweger2023abraxas1orchestratesbrca1 pages 8-9)
- Baseline DSBR reporter frequencies were reported (HR 3.7×10−4; NHEJ 3.9×10−3; MMEJ 5.3×10−4; SSA 2.5×10−3), enabling quantitative context for pathway shifts. (sachsenweger2023abraxas1orchestratesbrca1 pages 3-6)
- The c.577C>T variant produced strong constitutive DDR phenotypes: 53BP1 up to 12-fold higher versus one comparator, γH2AX ≥6-fold higher untreated and ≥2-fold post-IR, MRE11 increased ~threefold post-IR (basal ~twofold), and RPA increased ≥twofold post-IR (basal ≥fivefold), alongside increased pRPA32 (~twofold by western). (sachsenweger2023abraxas1orchestratesbrca1 pages 3-6)

Mechanistically, the authors interpret these variants as causing dominant effects on BRCA1 complex partitioning (BRCA1-A vs BRCA1-C) and shifting repair pathway usage toward lower-fidelity repair. (sachsenweger2023abraxas1orchestratesbrca1 pages 1-2, sachsenweger2023abraxas1orchestratesbrca1 pages 8-9)

Two key model figures from this study visually summarize (i) which ABRAXAS1 interaction regions are lost in each truncation and (ii) the proposed pathway-rewiring model for DSB repair choice. (sachsenweger2023abraxas1orchestratesbrca1 media db056916, sachsenweger2023abraxas1orchestratesbrca1 media 2aec6fc2)

4.2 2024: motif-based interactome rewiring—quantitative impact of the R361Q NLS mutation

A 2024 Molecular Systems Biology study used a proteome-scale motif-based interaction approach (GenVar_HD2) and validated that ABRAXAS1 contains a functional NLS disrupted by the R361Q mutation. Quantitatively, the importin/karyopherin interaction affinity weakened about tenfold (wild-type KD = 7.5 μM vs R361Q KD = 75 μM), and the mutant showed more cytoplasmic localization, providing an experimentally tractable molecular explanation consistent with earlier founder-variant cellular phenotypes. (kliche2024proteomescalecharacterisationof pages 11-13)

A multiplexed chromatin-context dependency study of DSB repair proteins reported that BRCA1-A subunits BRCC36 (BRCC3), RAP80 (UIMC1), and BRE (BABAM2) exhibit N-synergies with euchromatic features, and ABRAXAS1 “shows similar patterns but did not pass the significance threshold.” This suggests ABRAXAS1’s influence on pathway balance may be chromatin-context-dependent and is detectable in large-scale functional screens, even if weaker than other BRCA1-A components. (vergara2024widespreadchromatincontextdependencies pages 7-9)

4.4 2022 (supporting recent directions): RNA-dependent and RNA-binding behavior of ABRAXAS1

A proteome-wide screen for RNA-dependent proteins in A549 lung cancer cells (R-DeeP) identified 1189 RNA-dependent proteins, including ABRAXAS1, and validated ABRAXAS1 RNA dependence by western blot; importantly, the study reports that direct RNA interaction was verified by iCLIP2 for “the mitosis-related protein ABRAXAS1.” This suggests ABRAXAS1 may participate in RNA-associated complexes or RNA-dependent assemblies in some cell contexts, a direction that could broaden functional annotation beyond canonical BRCA1-A scaffolding. (rajagopal2022proteomewideidentificationof pages 1-2, rajagopal2022proteomewideidentificationof pages 5-7)

5) Current applications and real-world implementations

5.1 Hereditary cancer genetics and variant interpretation

ABRAXAS1 has clear relevance to hereditary breast cancer genetics through multiple lines of evidence:
- A Finnish founder germline variant c.1082G>A (p.Arg361Gln; R361Q) lies in the ABRAXAS1 NLS and has functional cellular evidence of impaired nuclear localization and reduced BRCA1 and CtIP nuclear foci formation, supporting pathogenic interpretation in a hereditary cancer context. (bose2019brca1mislocalizationleads pages 1-1, bose2019brca1mislocalizationleads pages 1-3)
- A mechanistic summary of this founder variant reports a mean breast cancer onset age of 46 years (range 35–53) in carriers, comparable to reported Finnish BRCA1/BRCA2 carrier onset ages in that source, providing a clinically interpretable statistic linked to ABRAXAS1. (bose2019molecularandfunctional pages 56-59)
- The 2023 truncation study provides functional evidence that heterozygous truncations can exert dominant-negative effects via complex rewiring and increased low-fidelity DSBR pathway usage, implying that ABRAXAS1 variant interpretation should consider pathway balance (SSA/MMEJ/NHEJ derepression) rather than only classic HR loss. (sachsenweger2023abraxas1orchestratesbrca1 pages 1-2, sachsenweger2023abraxas1orchestratesbrca1 pages 3-6)

5.2 Therapeutic interpretation (current limits)

A clinically important negative result from the 2023 truncation study is that heterozygous ABRAXAS1 mutation carriers did not show haploinsufficiency for HR proficiency by several assays and did not show altered PARP-inhibitor sensitivity, despite evidence of mutagenic pathway derepression and DDR abnormalities. This suggests ABRAXAS1 variants may not automatically confer a “BRCA-like” homologous recombination deficiency phenotype in the heterozygous state, limiting immediate extrapolation to PARP inhibitor eligibility based solely on ABRAXAS1 carrier status. (sachsenweger2023abraxas1orchestratesbrca1 pages 1-2, sachsenweger2023abraxas1orchestratesbrca1 pages 8-9)

6) Disease associations (database-level summary)

Open Targets reports disease associations for ABRAXAS1 including breast carcinoma/breast cancer, ovarian dysfunction, and inherited cancer-predisposing syndromes, with evidence entries linked to literature and variant records. This supports its placement among cancer predisposition/DDR-associated genes in biomedical databases. (OpenTargets Search: -ABRAXAS1,FAM175A,CCDC98)

7) Expert opinions and synthesis (authoritative interpretations)

7.1 ABRAXAS1 as a “functionalizer” of a shared DUB core

A consistent interpretation across high-quality structural work and reviews is that ABRAXAS1 (BRCA1-A) and ABRO1 (BRISC) are subcomplex-specific “functionalizers” of the same BRCC36 DUB core: they determine compartmentalization, recruitment to specific ubiquitin/SUMO marks, and regulatory constraints, while BRCC36 supplies the K63-specific catalytic activity. This adaptor-driven specialization model is central for functional annotation and for reasoning about phenotypes of ABRAXAS1 variants. (julius2020brca1aandbrisc pages 1-3, julius2019structuralbasisof pages 10-12)

7.2 ABRAXAS1 variants: dominant-negative and network-rewiring mechanisms

The recent 2023 patient-derived work emphasizes that truncations lacking the BRCA1-binding C-terminus can retain interaction capacity for other BRCA1-A partners (e.g., RAP80), plausibly allowing dominant complex perturbation rather than simple loss-of-function. This “rewiring” concept helps explain why some heterozygous ABRAXAS1 variants alter pathway choice without producing strong HRD signatures and why functional studies are needed for variant classification. (sachsenweger2023abraxas1orchestratesbrca1 pages 1-2)

8) Summary of key functional annotation statements (evidence-weighted)

  1. Primary function: ABRAXAS1 is a non-enzymatic scaffold/adaptor that assembles and targets the nuclear BRCA1-A complex; it activates and positions the BRCC36 K63-specific deubiquitinase and mediates phospho-dependent binding to BRCA1 BRCT domains. (julius2020brca1aandbrisc pages 3-6, julius2019structuralbasisof pages 10-12)
  2. Primary biological process: DNA damage response at DSBs, including editing of K63-ubiquitin chromatin signals and modulation of end resection/repair pathway balance through BRCA1 sequestration. (julius2020brca1aandbrisc pages 1-3, julius2019structuralbasisof pages 10-12)
  3. Cellular localization: Predominantly nuclear (BRCA1-A), dependent on an ABRAXAS1 NLS; NLS variants (R361Q) impair nuclear localization and BRCA1 foci. (julius2020brca1aandbrisc pages 3-6, bose2019brca1mislocalizationleads pages 1-3, kliche2024proteomescalecharacterisationof pages 11-13)
  4. Recent expansions of function: ABRAXAS1 shows RNA-dependent behavior and direct RNA interaction in iCLIP2 in a cancer cell context, suggesting additional RNA-associated roles or assemblies beyond canonical BRCA1-A. (rajagopal2022proteomewideidentificationof pages 1-2, rajagopal2022proteomewideidentificationof pages 5-7)
  5. Clinical relevance: Germline variants (founder missense R361Q; truncations) have functional evidence consistent with hereditary breast cancer predisposition mechanisms, though heterozygous truncations may not yield classic HRD/PARP sensitivity phenotypes. (bose2019molecularandfunctional pages 56-59, sachsenweger2023abraxas1orchestratesbrca1 pages 1-2)

References (URLs and publication dates)

  • Kyrieleis OJP et al. Cell Reports (Dec 2016). “Three-Dimensional Architecture of the Human BRCA1-A Histone Deubiquitinase Core Complex.” https://doi.org/10.1016/j.celrep.2016.11.063 (kyrieleis2016threedimensionalarchitectureof pages 1-3)
  • Rabl J et al. Molecular Cell (Aug 2019). “Structural Basis of BRCC36 Function in DNA Repair and Immune Regulation.” https://doi.org/10.1016/j.molcel.2019.06.002 (julius2019structuralbasisof pages 1-3)
  • Bose M et al. Human Molecular Genetics (Dec 2019). “BRCA1 mislocalization leads to aberrant DNA damage response in heterozygous ABRAXAS1 mutation carrier cells.” https://doi.org/10.1093/hmg/ddz252 (bose2019brca1mislocalizationleads pages 1-3)
  • Rabl J. Biomolecules (Oct 2020). “BRCA1-A and BRISC: Multifunctional Molecular Machines for Ubiquitin Signaling.” https://doi.org/10.3390/biom10111503 (julius2020brca1aandbrisc pages 1-3)
  • Rajagopal V et al. Cancers (Basel) (Dec 12, 2022). “Proteome-Wide Identification of RNA-Dependent Proteins in Lung Cancer Cells.” https://doi.org/10.3390/cancers14246109 (rajagopal2022proteomewideidentificationof pages 1-2)
  • Sachsenweger J et al. Cell Death & Disease (May 2023). “ABRAXAS1 orchestrates BRCA1 activities to counter genome destabilizing repair pathways—lessons from breast cancer patients.” https://doi.org/10.1038/s41419-023-05845-6 (sachsenweger2023abraxas1orchestratesbrca1 pages 8-9)
  • Kliche J et al. Molecular Systems Biology (Published online Jul 15, 2024). “Proteome-scale characterisation of motif-based interactome rewiring by disease mutations.” https://doi.org/10.1038/s44320-024-00055-4 (kliche2024proteomescalecharacterisationof pages 1-2)
  • Vergara X et al. Nature Communications (version cited includes bioRxiv DOI; posted Oct 7, 2022; Nat Commun publication listed 2024). “Widespread chromatin context-dependencies of DNA double-strand break repair proteins.” https://doi.org/10.1101/2022.10.07.511243 (vergara2024widespreadchromatincontextdependencies pages 7-9)
  • Open Targets Platform (accessed via tool): ABRAXAS1 disease associations. (OpenTargets Search: -ABRAXAS1,FAM175A,CCDC98)

References

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Artifacts

Citations

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  2. vergara2024widespreadchromatincontextdependencies pages 7-9
  3. bose2019molecularandfunctional pages 56-59
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  5. julius2019structuralbasisof pages 1-3
  6. rajagopal2022proteomewideidentificationof pages 1-2
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📚 Additional Documentation

Notes

(ABRAXAS1-notes.md)

ABRAXAS1 review notes

Evidence setup

  • just fetch-gene human ABRAXAS1 seeded the UniProt, GOA, Reactome, PANTHER family, and review stub files on 2026-06-03.
  • Falcon deep research was attempted with just deep-research-falcon human ABRAXAS1 --fallback perplexity-lite. Falcon timed out after 600 seconds; the perplexity-lite fallback then failed with a Perplexity API 401 quota error. No provider deep-research file was produced, so this review uses cached publications, UniProt, Reactome, PANTHER, and PN projection files directly.

Functional synthesis

ABRAXAS1/FAM175A/CCDC98 is a nuclear BRCA1-A complex scaffold and ubiquitin-recognition subunit. The primary literature identifies Abraxas as a BRCA1 BRCT-binding phosphoprotein and RAP80 partner: PMID:17525340 and PMID:17525340.

The supported biological role is DNA double-strand break response and checkpoint/repair signaling, not a standalone catalytic activity. The key experimental summary is that PMID:17525340. A second study frames CCDC98 as the factor that mediates BRCA1-RAP80 association and BRCA1-dependent G2/M checkpoint activation PMID:17643121.

ABRAXAS1 is also an organizer of the RAP80/BRCA1-A complex. Feng et al. describe CCDC98 as central to assembly: PMID:19261748. The BRCA1-A/RAP80 complex has BRCC36 K63-linked deubiquitinase activity, but the catalytic subunit is BRCC36, while Abraxas is required for that activity in the RAP80 complex context PMID:20656689.

PN projection decision

The PN projection has three ABRAXAS1 rows:

  • GO:0070531 BRCA1-A complex: already exact in GOA and accepted.
  • GO:0006281 DNA repair: already entailed by GOA via GO:0006302 double-strand break repair, so no new annotation is needed.
  • GO:0000151 ubiquitin ligase complex: new to GOA from the PN group Ubiquitin Proteasome System|E3 ubiquitin and UBL ligases|idiosyncratic RING complex. I did not add this as a proposed annotation. ABRAXAS1 is part of BRCA1-A, but the gene-level evidence supports scaffold/polyubiquitin-binding and BRCC36 DUB support rather than direct membership in a generic ubiquitin ligase complex. The PN mapping itself says this is a shared E3-complex bucket and warns against assigning catalytic activity to every subunit.

Annotation cautions

  • protein binding rows are real interaction evidence but too uninformative for core molecular function. Mechanistic papers should be interpreted as BRCA1-A complex assembly, RAP80/BRCA1/BRCC36 interaction, and polyubiquitin-dependent recruitment rather than retained as generic protein binding.
  • The IBA microtubule/spindle annotations are projected through a PANTHER node supported by ABRAXAS2 (WITH/FROM: UniProtKB:Q15018) rather than ABRAXAS1-specific evidence. I marked microtubule binding, attachment of spindle microtubules to kinetochore, and mitotic spindle assembly for removal for ABRAXAS1.

Falcon deep research findings (2026-06-07)

A Falcon deep-research report (ABRAXAS1-deep-research-falcon.md, Edison Scientific) was generated successfully on 2026-06-07, superseding the earlier failed run noted above. It is consistent with the existing review and adds the following, with NEW/CONFIRMS/PROVISIONAL labels. PMIDs could not be resolved via tooling for several of these primary papers (PubMed MCP unavailable); where only a DOI was available it is given, and these citations are kept in notes only rather than added as guessed PMIDs to the YAML.

  • CONFIRMS (molecular function / mechanism): ABRAXAS1 is a non-catalytic scaffold/adaptor with an N-terminal MPN-/JAMM-like domain that is catalytically inactive (MPN-) and acts as a DEUBAD-like activator/positioner of the K63-specific DUB BRCC36; ABRAXAS1 itself does not deubiquitinate. This matches the existing KEEP polyubiquitin-binding / not the catalytic DUB framing [PMID:20656689 "Abraxas and BRCC45 were essential for BRCC36 DUB activity within the RAP80 complex"; Rabl 2020 review doi:10.3390/biom10111503; Kyrieleis 2016 doi:10.1016/j.celrep.2016.11.063].

  • NEW (structural architecture): Negative-stain EM of a reconstituted human BRCA1-A core (Abraxas/BRCC36/BRCC45/MERIT40) supports a V-shaped "superdimer" (dimer of heterotetramers) with ABRAXAS1-BRCC36 at the base and BRCC45/MERIT40 in the arms; complexes prefer longer K63 chains (>=4 Ub), and RAP80 enhances targeting to mixed SUMO-K63 chains [Kyrieleis 2016 doi:10.1016/j.celrep.2016.11.063; Rabl 2019 Mol Cell doi:10.1016/j.molcel.2019.06.002]. Adds structural detail beyond current complex-membership annotations; no annotation change warranted.

  • NEW (domain map / NLS, clinical): ABRAXAS1 has an NLS (~aa 358-361, incl. Arg361) required for nuclear import of BRCA1-A; the Finnish founder variant c.1082G>A p.Arg361Gln (R361Q) impairs nuclear localization and reduces BRCA1/CtIP foci [Bose 2019 Hum Mol Genet doi:10.1093/hmg/ddz252]. A 2024 motif-interactome study (already cited as PMID:39009827) quantified the R361Q effect: importin/karyopherin affinity weakened ~10-fold (WT KD 7.5 uM vs R361Q 75 uM) with increased cytoplasmic localization PMID:39009827. The C-terminal pSPxF/SPTF motif (~aa 406-409; S404 damage-inducible, S406 constitutive, F409 critical) mediates phospho-dependent BRCA1 BRCT binding.

  • NEW (disease mechanism / pathway choice): Two truncating germline ABRAXAS1 variants from early-onset breast cancer patients - c.1106dup (p.Ser370Ilefs2, loses the C-terminal BRCA1-binding SPTF motif) and c.577C>T (p.Arg193, also lacks the BRCC36-interaction region) - act dominantly to shift BRCA1 partitioning from BRCA1-A toward BRCA1-C and derepress mutagenic DSB repair (SSA/MMEJ/NHEJ) without impairing HR; notably heterozygous carriers did NOT show HR deficiency or altered PARP-inhibitor sensitivity [Sachsenweger 2023 Cell Death Dis doi:10.1038/s41419-023-05845-6]. Reframes ABRAXAS1 as a "fine-tuner" of BRCA1 repair-pathway choice (restrains end resection / mutagenic pathways) rather than a simple HR-promoting factor. Supports the existing positive regulation of DNA repair / checkpoint framing; no existing annotation contradicted.

  • PROVISIONAL / low-confidence (RNA association): A proteome-wide R-DeeP screen in A549 lung cancer cells identified ABRAXAS1 as RNA-dependent, with direct RNA interaction validated by iCLIP2 ("mitosis-related protein ABRAXAS1") [Rajagopal 2022 Cancers doi:10.3390/cancers14246109]. This is a single high-throughput study in one cell line; flagged provisional and NOT used to add any RNA-binding GO annotation. Worth a curator question only.

  • CONFIRMS (paralog specialization): ABRAXAS1 (BRCA1-A, nuclear) vs paralog ABRO1/ABRAXAS2 (BRISC, largely non-nuclear) partition the shared BRCC36/BRE/MERIT40 core. This reinforces the existing REMOVE decisions on microtubule/spindle IBA terms traceable to ABRAXAS2 [Rabl 2020 doi:10.3390/biom10111503; Rabl 2019 doi:10.1016/j.molcel.2019.06.002].

Pn Notes

(ABRAXAS1-pn-notes.md)

ABRAXAS1 PN Consistency Notes

  • Generated: 2026-06-18
  • Project: PROTEOSTASIS
  • Scope: PN consistency rereview against local AIGR review and available deep-research artifacts
  • UniProt: Q6UWZ7
  • AIGR review status: DRAFT
  • Review batch: proteostasis-batch-2026-06-03 (PR 1327)
  • Batch change status: added

Source Files Checked

Deep Research Files

AIGR Review Snapshot

  • Description: ABRAXAS1 encodes a nuclear BRCA1-A complex subunit that acts as a scaffold linking BRCA1, UIMC1/RAP80, BRCC3/BRCC36, BABAM proteins, and ubiquitin-dependent DNA damage-site signaling. The protein contains an MPN-like domain, binds polyubiquitin as part of the BRCA1-A/RAP80 complex, and supports BRCA1 recruitment, DNA double-strand break repair, K63-ubiquitin signal editing by BRCC36, and G2/M DNA damage checkpoint responses.
  • Existing/core annotation action counts: ACCEPT: 30; KEEP_AS_NON_CORE: 4; MARK_AS_OVER_ANNOTATED: 11; MODIFY: 2; REMOVE: 3

PN Consistency Summary

  • Consistency: Consistent on the core: deep-research/notes, review, and PN all converge on ABRAXAS1 as a nuclear BRCA1-A/RAP80 scaffold + polyubiquitin-reader (MPN-like) in DNA damage response. Review accepts GO:0070531 BRCA1-A complex (core), GO:0031593 polyubiquitin-dependent binding, GO:0006302 DSB repair, GO:0045739 positive regulation of DNA repair, GO:0007095 G2 checkpoint. One nuance: the PN group projects GO:0000151 "ubiquitin ligase complex," but the review prefers the more specific GO:0070531 and explicitly calls GO:0000151 "more precise than the PN-projected generic ubiquitin-ligase-complex bucket." Note ABRAXAS1 is a scaffold/DUB-support subunit, not an E3 catalytic ligase — so the RING/ligase framing is a placement convenience, not a function claim (review is careful here). No hard contradiction.
  • PN story / NEW pressure: PN's DNA-repair + ubiquitin-binding + BRCA1-A story is fully captured (GO:0006281 entailed by accepted GO:0006302; GO:0070531 present; GO:0031593 present). All PN-projected terms verified real. Conclusion: already captured; the only over-reach is the generic ligase-complex bucket, which the review supersedes with GO:0070531.
  • Evidence alignment: Good overlap. PN reference titles cite PMID:17525340 (row 1) and PMID:19261749 (row 2 signature domain, IPR037518/MPN) — both are central review references (17525340 = ACCEPT-supporting for nucleus/checkpoint/DSB; 19261749 = NBA1/BRCA1-A + polyubiquitin binding). PN and review cite the same anchor papers.
  • Verdict: Consistent; PN captured (review uses more specific complex term, correctly avoids E3-catalytic over-claim). Status is DRAFT. No substantive edits warranted (optional: finalize DRAFT→COMPLETE after the open RNA-binding and SSA/MMEJ negative-regulation questions are settled).

Full Consistency Review

  • UniProt: Q6UWZ7 · batch: proteostasis-batch-2026-06-03 · review status: DRAFT
  • PN placement (2 rows): UPS|E3 ubiquitin and UBL ligases|idiosyncratic RING complex|BRCA1-A complex|ubiquitin binding AND UPS|Ubiquitin and UBL binding|DNA repair|BRCA1-A complex component|idiosyncratic Ub binding / MPN ; PN-node mapping: type BRCA1-A complex=mapped→GO:0070531 (already_in_goa_exact); group idiosyncratic RING complex=mapped→GO:0000151 ubiquitin ligase complex (new_to_goa); group ...|DNA repair=mapped→GO:0006281 DNA repair (entailed_by_goa_closure); class E3...ligases/Ub and UBL binding=context_only; branch UPS=no_mapping.
  • Consistency: Consistent on the core: deep-research/notes, review, and PN all converge on ABRAXAS1 as a nuclear BRCA1-A/RAP80 scaffold + polyubiquitin-reader (MPN-like) in DNA damage response. Review accepts GO:0070531 BRCA1-A complex (core), GO:0031593 polyubiquitin-dependent binding, GO:0006302 DSB repair, GO:0045739 positive regulation of DNA repair, GO:0007095 G2 checkpoint. One nuance: the PN group projects GO:0000151 "ubiquitin ligase complex," but the review prefers the more specific GO:0070531 and explicitly calls GO:0000151 "more precise than the PN-projected generic ubiquitin-ligase-complex bucket." Note ABRAXAS1 is a scaffold/DUB-support subunit, not an E3 catalytic ligase — so the RING/ligase framing is a placement convenience, not a function claim (review is careful here). No hard contradiction.
  • PN story / NEW pressure: PN's DNA-repair + ubiquitin-binding + BRCA1-A story is fully captured (GO:0006281 entailed by accepted GO:0006302; GO:0070531 present; GO:0031593 present). All PN-projected terms verified real. Conclusion: already captured; the only over-reach is the generic ligase-complex bucket, which the review supersedes with GO:0070531.
  • Mapping strategy: Group node GO:0000151 should be treated as non-propagating to ABRAXAS1 (review holds the narrower, child term GO:0070531). The DNA-repair group→GO:0006281 is already entailed. Type node GO:0070531 is correct. No new propagation needed.
  • Evidence alignment: Good overlap. PN reference titles cite PMID:17525340 (row 1) and PMID:19261749 (row 2 signature domain, IPR037518/MPN) — both are central review references (17525340 = ACCEPT-supporting for nucleus/checkpoint/DSB; 19261749 = NBA1/BRCA1-A + polyubiquitin binding). PN and review cite the same anchor papers.
  • Verdict: Consistent; PN captured (review uses more specific complex term, correctly avoids E3-catalytic over-claim). Status is DRAFT. No substantive edits warranted (optional: finalize DRAFT→COMPLETE after the open RNA-binding and SSA/MMEJ negative-regulation questions are settled).

PN Dossier Context

  • review_batch: proteostasis-batch-2026-06-03
  • review_yaml: genes/human/ABRAXAS1/ABRAXAS1-ai-review.yaml
  • PN workbook rows: 2

PN row 1: Ubiquitin Proteasome System | E3 ubiquitin and UBL ligases | idiosyncratic RING complex | BRCA1-A complex | ubiquitin binding

  • UniProt: Q6UWZ7
  • In branches: UPS
  • Signature domains: (none)
  • Auxiliary domains: PMID: 19261749 (IPR037518)
  • PN references (titles):
    • 17525340
  • PN-node mapping records (path + ancestors):
    • [subtype] Ubiquitin Proteasome System|E3 ubiquitin and UBL ligases|idiosyncratic RING complex|BRCA1-A complex|ubiquitin binding
      status=no_mapping scope= GO=[]
      rationale: Reviewed as a narrower E3-ligase architecture, component, or domain subdivision already covered by the curated parent E3 mapping. No additional direct GO mapping is needed at this node.
    • [type] Ubiquitin Proteasome System|E3 ubiquitin and UBL ligases|idiosyncratic RING complex|BRCA1-A complex
      status=mapped scope=ok_for_propagation_to_go GO=[GO:0070531 BRCA1-A complex]
      rationale: This PN type denotes BRCA1-A complex members. The matching GO cellular-component term is BRCA1-A complex.
    • [group] Ubiquitin Proteasome System|E3 ubiquitin and UBL ligases|idiosyncratic RING complex
      status=mapped scope=ok_for_propagation_to_go GO=[GO:0000151 ubiquitin ligase complex]
      rationale: This PN group is an E3 ligase complex bucket. The safest shared GO target is ubiquitin ligase complex membership rather than assigning catalytic activity to every subunit.
    • [class] Ubiquitin Proteasome System|E3 ubiquitin and UBL ligases
      status=context_only scope=too_broad_to_propagate GO=[GO:0061630 ubiquitin protein ligase activity]
      rationale: This class is a genuine E3-ligase context, but its descendants include catalytic ligases, cullin scaffolds, substrate receptors, adaptors, cofactors, regulators, and UBL modifier systems. A class-level propagation would over-annotate.
    • [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 | BRCA1-A complex component | idiosyncratic Ub binding / MPN

  • UniProt: Q6UWZ7
  • 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|BRCA1-A 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|BRCA1-A 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:0000151 ubiquitin ligase complex | scope=ok_for_propagation_to_go | goa_status=new_to_goa | from=Ubiquitin Proteasome System|E3 ubiquitin and UBL ligases|idiosyncratic RING complex
  • GO:0070531 BRCA1-A complex | scope=ok_for_propagation_to_go | goa_status=already_in_goa_exact | from=Ubiquitin Proteasome System|E3 ubiquitin and UBL ligases|idiosyncratic RING complex|BRCA1-A complex
  • GO:0006281 DNA repair | scope=ok_for_propagation_to_go | goa_status=entailed_by_goa_closure | 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: Q6UWZ7
gene_symbol: ABRAXAS1
product_type: PROTEIN
status: DRAFT
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: >-
  ABRAXAS1 encodes a nuclear BRCA1-A complex subunit that acts as a scaffold linking BRCA1, UIMC1/RAP80, BRCC3/BRCC36,
  BABAM proteins, and ubiquitin-dependent DNA damage-site signaling. The protein contains an MPN-like domain, binds
  polyubiquitin as part of the BRCA1-A/RAP80 complex, and supports BRCA1 recruitment, DNA double-strand break repair,
  K63-ubiquitin signal editing by BRCC36, and G2/M DNA damage checkpoint responses.
alternative_products:
- name: '1'
  id: Q6UWZ7-1
- name: '2'
  id: Q6UWZ7-2
  sequence_note: VSP_058196
existing_annotations:
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  review:
    summary: >-
      Supported nuclear localization. ABRAXAS1 acts in the nuclear DNA damage response and localizes to DNA damage
      sites within the nucleus.
    action: ACCEPT
    reason: >-
      The UniProt record and the original BRCA1-A studies place ABRAXAS1 in the nucleus, where it recruits/organizes
      BRCA1-A complex activity at DNA double-strand breaks.
    supported_by:
    - reference_id: file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
      supporting_text: Nucleus {ECO:0000269|PubMed:17525340, ECO:0000269|PubMed:17643121,
        ECO:0000269|PubMed:17643122}.
    - reference_id: PMID:17525340
      supporting_text: RAP80 was required for optimal accumulation of BRCA1 on damaged DNA (foci) in response
        to ionizing radiation
- term:
    id: GO:0008017
    label: microtubule binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: >-
      Likely paralog/family over-propagation. The IBA trace for this microtubule-binding term cites ABRAXAS2 rather
      than ABRAXAS1-specific evidence.
    action: REMOVE
    reason: >-
      ABRAXAS1 literature, UniProt, Reactome, and PN context support a nuclear BRCA1-A DNA damage-response scaffold,
      not microtubule binding. No ABRAXAS1-specific microtubule-binding evidence was found in the cached evidence
      set.
    additional_reference_ids:
    - file:interpro/panther/PTHR31728/PTHR31728-entries.csv
    supported_by:
    - reference_id: file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
      supporting_text: Involved in DNA damage response and double-strand break (DSB) repair.
    - reference_id: file:human/ABRAXAS1/ABRAXAS1-notes.md
      supporting_text: The IBA microtubule/spindle annotations are projected through a PANTHER node supported
        by ABRAXAS2
- 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: >-
      Likely paralog/family over-propagation. The kinetochore-microtubule attachment IBA is not supported by ABRAXAS1-specific
      DNA damage literature.
    action: REMOVE
    reason: >-
      The with/from metadata points to ABRAXAS2 for the spindle branch, while ABRAXAS1 evidence supports BRCA1-A
      complex-mediated DNA damage signaling. This process would overstate ABRAXAS1 biology.
    additional_reference_ids:
    - file:interpro/panther/PTHR31728/PTHR31728-entries.csv
    supported_by:
    - reference_id: file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
      supporting_text: Involved in DNA damage response and double-strand break (DSB) repair.
    - reference_id: file:human/ABRAXAS1/ABRAXAS1-notes.md
      supporting_text: I marked `microtubule binding`, `attachment of spindle microtubules to kinetochore`,
        and `mitotic spindle assembly` for removal for ABRAXAS1.
- term:
    id: GO:0031593
    label: polyubiquitin modification-dependent protein binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: >-
      Core molecular function. ABRAXAS1 is part of a BRCA1-A/RAP80 complex that recognizes ubiquitinated damage-site
      chromatin and has polyubiquitin-binding capacity.
    action: ACCEPT
    reason: >-
      The term captures the ubiquitin-recognition side of ABRAXAS1 biology better than generic protein binding.
      It should be retained for both direct IDA and IBA evidence.
    supported_by:
    - reference_id: PMID:19261749
      supporting_text: four members of the BRCA1-A complex possess a polyubiquitin chain-binding capability
    - reference_id: PMID:20656689
      supporting_text: RAP80, in turn, is recruited to DSBs through its tandem ubiquitin-interacting motifs
        (UIMs) ( 6 , 14 – 16 ), which specifically recognize 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: >-
      Likely paralog/family over-propagation. The mitotic-spindle-assembly IBA is not supported for ABRAXAS1 by
      the reviewed evidence.
    action: REMOVE
    reason: >-
      ABRAXAS1 participates in nuclear DNA damage repair/checkpoint signaling. The PANTHER IBA spindle call is traceable
      to ABRAXAS2 and should not be propagated to ABRAXAS1 without gene-specific evidence.
    additional_reference_ids:
    - file:interpro/panther/PTHR31728/PTHR31728-entries.csv
    supported_by:
    - reference_id: file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
      supporting_text: Involved in DNA damage response and double-strand break (DSB) repair.
    - reference_id: file:human/ABRAXAS1/ABRAXAS1-notes.md
      supporting_text: I marked `microtubule binding`, `attachment of spindle microtubules to kinetochore`,
        and `mitotic spindle assembly` for removal for ABRAXAS1.
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: >-
      Supported nuclear localization. ABRAXAS1 acts in the nuclear DNA damage response and localizes to DNA damage
      sites within the nucleus.
    action: ACCEPT
    reason: >-
      The UniProt record and the original BRCA1-A studies place ABRAXAS1 in the nucleus, where it recruits/organizes
      BRCA1-A complex activity at DNA double-strand breaks.
    supported_by:
    - reference_id: file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
      supporting_text: Nucleus {ECO:0000269|PubMed:17525340, ECO:0000269|PubMed:17643121,
        ECO:0000269|PubMed:17643122}.
    - reference_id: PMID:17525340
      supporting_text: RAP80 was required for optimal accumulation of BRCA1 on damaged DNA (foci) in response
        to ionizing radiation
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:17525340
  qualifier: enables
  review:
    summary: >-
      Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A
      complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome
      rows are even less suitable as function claims.
    supported_by:
    - reference_id: PMID:17525340
      supporting_text: identified a protein, Abraxas, that directly binds the BRCA1 BRCT repeats
    - reference_id: PMID:20656689
      supporting_text: The RAP80 complex is a five-member stoichiometric complex consisting of RAP80, BRCC36,
        BRCC45, Abraxas, and MERIT40
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:17643121
  qualifier: enables
  review:
    summary: >-
      Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A
      complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome
      rows are even less suitable as function claims.
    supported_by:
    - reference_id: PMID:17643121
      supporting_text: CCDC98 is a BRCA1 binding partner that mediates BRCA1 function in response to DNA
        damage.
    - reference_id: PMID:20656689
      supporting_text: The RAP80 complex is a five-member stoichiometric complex consisting of RAP80, BRCC36,
        BRCC45, Abraxas, and MERIT40
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:18077395
  qualifier: enables
  review:
    summary: >-
      Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A
      complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome
      rows are even less suitable as function claims.
    supported_by:
    - reference_id: PMID:18077395
      supporting_text: Rap80 contains an Abraxas interaction domain
    - reference_id: PMID:20656689
      supporting_text: The RAP80 complex is a five-member stoichiometric complex consisting of RAP80, BRCC36,
        BRCC45, Abraxas, and MERIT40
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:19615732
  qualifier: enables
  review:
    summary: >-
      Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A
      complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome
      rows are even less suitable as function claims.
    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:29656893
  qualifier: enables
  review:
    summary: >-
      Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A
      complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome
      rows are even less suitable as function claims.
    supported_by:
    - reference_id: PMID:29656893
      supporting_text: we generated high-resolution interaction neighborhood maps of the endogenously
        expressed DNA repair factors 53BP1, BRCA1, and MDC1
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:34591612
  qualifier: enables
  review:
    summary: >-
      Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A
      complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome
      rows are even less suitable as function claims.
    supported_by:
    - reference_id: PMID:34591612
      supporting_text: we generated comprehensive interaction maps for 40 frequently altered BC proteins
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:35156780
  qualifier: enables
  review:
    summary: >-
      Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A
      complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome
      rows are even less suitable as function claims.
    supported_by:
    - reference_id: PMID:35156780
      supporting_text: high-throughput screening variant of the Mammalian Membrane Two-Hybrid
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:36012204
  qualifier: enables
  review:
    summary: >-
      Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A
      complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome
      rows are even less suitable as function claims.
    supported_by:
    - reference_id: PMID:36012204
      supporting_text: proximity labeling approaches identified both known and additional CFTR protein
        partners
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:39009827
  qualifier: enables
  review:
    summary: >-
      Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A
      complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome
      rows are even less suitable as function claims.
    supported_by:
    - reference_id: PMID:39009827
      supporting_text: we identified 366 mutation-modulated interactions
- term:
    id: GO:0016604
    label: nuclear body
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  qualifier: located_in
  review:
    summary: >-
      Non-core localization. HPA reports nuclear-body staining, while mechanistic ABRAXAS1 biology centers on DNA
      damage foci/BRCA1-A complex recruitment.
    action: KEEP_AS_NON_CORE
    reason: >-
      This cellular component is plausible as a localization observation, but it is less informative than nucleus/nucleoplasm
      and BRCA1-A complex membership for the gene product function.
    supported_by:
    - reference_id: file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
      supporting_text: Localizes at sites of DNA damage at double-strand breaks (DSBs).
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: NAS
  original_reference_id: PMID:20656689
  qualifier: located_in
  review:
    summary: >-
      Supported nuclear localization. ABRAXAS1 acts in the nuclear DNA damage response and localizes to DNA damage
      sites within the nucleus.
    action: ACCEPT
    reason: >-
      The UniProt record and the original BRCA1-A studies place ABRAXAS1 in the nucleus, where it recruits/organizes
      BRCA1-A complex activity at DNA double-strand breaks.
    supported_by:
    - reference_id: file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
      supporting_text: Nucleus {ECO:0000269|PubMed:17525340, ECO:0000269|PubMed:17643121,
        ECO:0000269|PubMed:17643122}.
    - reference_id: PMID:17525340
      supporting_text: RAP80 was required for optimal accumulation of BRCA1 on damaged DNA (foci) in response
        to ionizing radiation
- term:
    id: GO:0006282
    label: regulation of DNA repair
  evidence_type: NAS
  original_reference_id: PMID:20656689
  qualifier: involved_in
  review:
    summary: >-
      The broad regulation-of-DNA-repair annotation is directionally correct but less precise than positive regulation
      of DNA repair for ABRAXAS1.
    action: MODIFY
    reason: >-
      ABRAXAS1 promotes BRCA1-A complex recruitment/stability and DNA repair after damage; the reviewed IMP annotations
      already use the more informative positive-regulation term.
    proposed_replacement_terms:
    - id: GO:0045739
      label: positive regulation of DNA repair
    supported_by:
    - reference_id: PMID:17525340
      supporting_text: Both Abraxas and RAP80 were required for DNA damage resistance, G(2)-M checkpoint
        control, and DNA repair.
    - reference_id: PMID:19261748
      supporting_text: a stable complex containing MERIT40 acts early in DNA damage response and regulates
        damage-dependent BRCA1 localization
- term:
    id: GO:0044818
    label: mitotic G2/M transition checkpoint
  evidence_type: NAS
  original_reference_id: PMID:22369660
  qualifier: involved_in
  review:
    summary: >-
      The ComplexPortal/NAS checkpoint annotation is real but should be represented using the more specific DNA-damage
      checkpoint signaling term.
    action: MODIFY
    reason: >-
      ABRAXAS1 evidence concerns BRCA1-dependent G2/M checkpoint activation in response to DNA damage, not the generic
      mitotic G2/M transition checkpoint.
    proposed_replacement_terms:
    - id: GO:0007095
      label: mitotic G2 DNA damage checkpoint signaling
    supported_by:
    - reference_id: PMID:17643121
      supporting_text: CCDC98 controls both DNA damage-induced formation of BRCA1 foci and BRCA1-dependent
        G2/M checkpoint activation
    - reference_id: PMID:22369660
      supporting_text: Studies on A, B and C complexes of BRCA1 indicate that these complexes carry out
        functions of BRCA1 in cell cycle checkpoint control.
- term:
    id: GO:0070531
    label: BRCA1-A complex
  evidence_type: NAS
  original_reference_id: PMID:20656689
  qualifier: part_of
  review:
    summary: >-
      Core complex membership. ABRAXAS1 is a BRCA1-A complex subunit that organizes BRCA1, UIMC1/RAP80, BRCC3/BRCC36,
      BABAM proteins, and related DDR functions.
    action: ACCEPT
    reason: >-
      Multiple primary studies and Reactome support ABRAXAS1/FAM175A as a BRCA1-A complex component. This is more
      precise than the PN-projected generic ubiquitin-ligase-complex bucket.
    additional_reference_ids:
    - file:projects/PROTEOSTASIS/reports/pn_projection/pn_projected_gene_go_summary.tsv
    - file:projects/PROTEOSTASIS/mappings/ubiquitin_proteasome_system.yaml
    supported_by:
    - reference_id: PMID:19261749
      supporting_text: Proteomic analysis revealed that NBA1 is a component of the BRCA1 A complex, which also
        contains Brca1/Bard1, Abra1, RAP80, BRCC36, and BRE.
    - reference_id: Reactome:R-HSA-5683385
      supporting_text: Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called
        BRCA1-A complex at DNA DSBs
- term:
    id: GO:0007095
    label: mitotic G2 DNA damage checkpoint signaling
  evidence_type: IMP
  original_reference_id: PMID:17525340
  qualifier: involved_in
  review:
    summary: >-
      Core checkpoint process. ABRAXAS1/CCDC98 is required for BRCA1-dependent G2/M checkpoint signaling after DNA
      damage.
    action: ACCEPT
    reason: >-
      The original ABRAXAS1/CCDC98 work and later BRCA1-A review evidence support a G2 DNA damage checkpoint role.
      This is part of the DNA damage response function rather than a general mitotic-spindle role.
    supported_by:
    - reference_id: PMID:17643121
      supporting_text: CCDC98 controls both DNA damage-induced formation of BRCA1 foci and BRCA1-dependent
        G2/M checkpoint activation
    - reference_id: PMID:22369660
      supporting_text: Studies on A, B and C complexes of BRCA1 indicate that these complexes carry out
        functions of BRCA1 in cell cycle checkpoint control.
- term:
    id: GO:0007095
    label: mitotic G2 DNA damage checkpoint signaling
  evidence_type: IMP
  original_reference_id: PMID:17643121
  qualifier: involved_in
  review:
    summary: >-
      Core checkpoint process. ABRAXAS1/CCDC98 is required for BRCA1-dependent G2/M checkpoint signaling after DNA
      damage.
    action: ACCEPT
    reason: >-
      The original ABRAXAS1/CCDC98 work and later BRCA1-A review evidence support a G2 DNA damage checkpoint role.
      This is part of the DNA damage response function rather than a general mitotic-spindle role.
    supported_by:
    - reference_id: PMID:17643121
      supporting_text: CCDC98 controls both DNA damage-induced formation of BRCA1 foci and BRCA1-dependent
        G2/M checkpoint activation
    - reference_id: PMID:22369660
      supporting_text: Studies on A, B and C complexes of BRCA1 indicate that these complexes carry out
        functions of BRCA1 in cell cycle checkpoint control.
- term:
    id: GO:0007095
    label: mitotic G2 DNA damage checkpoint signaling
  evidence_type: IMP
  original_reference_id: PMID:19261748
  qualifier: involved_in
  review:
    summary: >-
      Core checkpoint process. ABRAXAS1/CCDC98 is required for BRCA1-dependent G2/M checkpoint signaling after DNA
      damage.
    action: ACCEPT
    reason: >-
      The original ABRAXAS1/CCDC98 work and later BRCA1-A review evidence support a G2 DNA damage checkpoint role.
      This is part of the DNA damage response function rather than a general mitotic-spindle role.
    supported_by:
    - reference_id: PMID:17643121
      supporting_text: CCDC98 controls both DNA damage-induced formation of BRCA1 foci and BRCA1-dependent
        G2/M checkpoint activation
    - reference_id: PMID:22369660
      supporting_text: Studies on A, B and C complexes of BRCA1 indicate that these complexes carry out
        functions of BRCA1 in cell cycle checkpoint control.
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-5683384
  qualifier: located_in
  review:
    summary: >-
      Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1
      are modeled at nuclear DNA double-strand breaks.
    action: ACCEPT
    reason: >-
      The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break
      events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
    supported_by:
    - reference_id: Reactome:R-HSA-5683385
      supporting_text: Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called
        BRCA1-A complex at DNA DSBs
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-5683385
  qualifier: located_in
  review:
    summary: >-
      Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1
      are modeled at nuclear DNA double-strand breaks.
    action: ACCEPT
    reason: >-
      The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break
      events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
    supported_by:
    - reference_id: Reactome:R-HSA-5683385
      supporting_text: Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called
        BRCA1-A complex at DNA DSBs
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-5683735
  qualifier: located_in
  review:
    summary: >-
      Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1
      are modeled at nuclear DNA double-strand breaks.
    action: ACCEPT
    reason: >-
      The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break
      events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
    supported_by:
    - reference_id: Reactome:R-HSA-5683385
      supporting_text: Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called
        BRCA1-A complex at DNA DSBs
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-5683801
  qualifier: located_in
  review:
    summary: >-
      Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1
      are modeled at nuclear DNA double-strand breaks.
    action: ACCEPT
    reason: >-
      The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break
      events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
    supported_by:
    - reference_id: Reactome:R-HSA-5683385
      supporting_text: Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called
        BRCA1-A complex at DNA DSBs
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-5684052
  qualifier: located_in
  review:
    summary: >-
      Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1
      are modeled at nuclear DNA double-strand breaks.
    action: ACCEPT
    reason: >-
      The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break
      events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
    supported_by:
    - reference_id: Reactome:R-HSA-5683385
      supporting_text: Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called
        BRCA1-A complex at DNA DSBs
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-5684071
  qualifier: located_in
  review:
    summary: >-
      Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1
      are modeled at nuclear DNA double-strand breaks.
    action: ACCEPT
    reason: >-
      The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break
      events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
    supported_by:
    - reference_id: Reactome:R-HSA-5683385
      supporting_text: Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called
        BRCA1-A complex at DNA DSBs
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-5686685
  qualifier: located_in
  review:
    summary: >-
      Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1
      are modeled at nuclear DNA double-strand breaks.
    action: ACCEPT
    reason: >-
      The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break
      events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
    supported_by:
    - reference_id: Reactome:R-HSA-5683385
      supporting_text: Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called
        BRCA1-A complex at DNA DSBs
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-5691411
  qualifier: located_in
  review:
    summary: >-
      Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1
      are modeled at nuclear DNA double-strand breaks.
    action: ACCEPT
    reason: >-
      The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break
      events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
    supported_by:
    - reference_id: Reactome:R-HSA-5683385
      supporting_text: Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called
        BRCA1-A complex at DNA DSBs
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-5693551
  qualifier: located_in
  review:
    summary: >-
      Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1
      are modeled at nuclear DNA double-strand breaks.
    action: ACCEPT
    reason: >-
      The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break
      events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
    supported_by:
    - reference_id: Reactome:R-HSA-5683385
      supporting_text: Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called
        BRCA1-A complex at DNA DSBs
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-69891
  qualifier: located_in
  review:
    summary: >-
      Supported Reactome-derived nuclear compartment annotation. The BRCA1-A complex events involving FAM175A/ABRAXAS1
      are modeled at nuclear DNA double-strand breaks.
    action: ACCEPT
    reason: >-
      The nucleoplasm location is consistent with ABRAXAS1 nuclear localization and Reactome DNA double-strand break
      events. These duplicate TAS rows reflect pathway-event participation rather than distinct localizations.
    supported_by:
    - reference_id: Reactome:R-HSA-5683385
      supporting_text: Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called
        BRCA1-A complex at DNA DSBs
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:19261748
  qualifier: enables
  review:
    summary: >-
      Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A
      complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome
      rows are even less suitable as function claims.
    supported_by:
    - reference_id: PMID:19261748
      supporting_text: CCDC98 binds to RAP80 via a large N-terminal region
    - reference_id: PMID:20656689
      supporting_text: The RAP80 complex is a five-member stoichiometric complex consisting of RAP80, BRCC36,
        BRCC45, Abraxas, and MERIT40
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:19261749
  qualifier: enables
  review:
    summary: >-
      Interaction evidence is real, but the GO term protein binding is too generic to describe ABRAXAS1 function.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      These IPI rows should not be treated as core molecular-function annotations. The informative biology is BRCA1-A
      complex assembly, RAP80/BRCA1/BRCC36 interactions, and polyubiquitin-dependent recruitment; broad interactome
      rows are even less suitable as function claims.
    supported_by:
    - reference_id: PMID:19261749
      supporting_text: four members of the BRCA1-A complex possess a polyubiquitin chain-binding capability
    - reference_id: PMID:20656689
      supporting_text: The RAP80 complex is a five-member stoichiometric complex consisting of RAP80, BRCC36,
        BRCC45, Abraxas, and MERIT40
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IDA
  original_reference_id: PMID:17525340
  qualifier: located_in
  review:
    summary: >-
      Supported nuclear localization. ABRAXAS1 acts in the nuclear DNA damage response and localizes to DNA damage
      sites within the nucleus.
    action: ACCEPT
    reason: >-
      The UniProt record and the original BRCA1-A studies place ABRAXAS1 in the nucleus, where it recruits/organizes
      BRCA1-A complex activity at DNA double-strand breaks.
    supported_by:
    - reference_id: file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
      supporting_text: Nucleus {ECO:0000269|PubMed:17525340, ECO:0000269|PubMed:17643121,
        ECO:0000269|PubMed:17643122}.
    - reference_id: PMID:17525340
      supporting_text: RAP80 was required for optimal accumulation of BRCA1 on damaged DNA (foci) in response
        to ionizing radiation
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IDA
  original_reference_id: PMID:17643121
  qualifier: located_in
  review:
    summary: >-
      Supported nuclear localization. ABRAXAS1 acts in the nuclear DNA damage response and localizes to DNA damage
      sites within the nucleus.
    action: ACCEPT
    reason: >-
      The UniProt record and the original BRCA1-A studies place ABRAXAS1 in the nucleus, where it recruits/organizes
      BRCA1-A complex activity at DNA double-strand breaks.
    supported_by:
    - reference_id: file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
      supporting_text: Nucleus {ECO:0000269|PubMed:17525340, ECO:0000269|PubMed:17643121,
        ECO:0000269|PubMed:17643122}.
    - reference_id: PMID:17525340
      supporting_text: RAP80 was required for optimal accumulation of BRCA1 on damaged DNA (foci) in response
        to ionizing radiation
- term:
    id: GO:0006302
    label: double-strand break repair
  evidence_type: IMP
  original_reference_id: PMID:17525340
  qualifier: involved_in
  review:
    summary: >-
      Core biological process. ABRAXAS1 is required for efficient DNA double-strand break repair through BRCA1-A
      recruitment and ubiquitin-dependent damage-site signaling.
    action: ACCEPT
    reason: >-
      Loss/depletion experiments in the original ABRAXAS1/CCDC98 papers support DNA repair and DNA damage resistance.
      The PN-projected broader DNA repair term is already entailed by this annotation.
    additional_reference_ids:
    - file:projects/PROTEOSTASIS/reports/pn_projection/pn_projected_gene_go_summary.tsv
    supported_by:
    - reference_id: PMID:17525340
      supporting_text: Both Abraxas and RAP80 were required for DNA damage resistance, G(2)-M checkpoint
        control, and DNA repair.
    - reference_id: PMID:19261748
      supporting_text: a stable complex containing MERIT40 acts early in DNA damage response and regulates
        damage-dependent BRCA1 localization
- term:
    id: GO:0006302
    label: double-strand break repair
  evidence_type: IMP
  original_reference_id: PMID:17643121
  qualifier: involved_in
  review:
    summary: >-
      Core biological process. ABRAXAS1 is required for efficient DNA double-strand break repair through BRCA1-A
      recruitment and ubiquitin-dependent damage-site signaling.
    action: ACCEPT
    reason: >-
      Loss/depletion experiments in the original ABRAXAS1/CCDC98 papers support DNA repair and DNA damage resistance.
      The PN-projected broader DNA repair term is already entailed by this annotation.
    additional_reference_ids:
    - file:projects/PROTEOSTASIS/reports/pn_projection/pn_projected_gene_go_summary.tsv
    supported_by:
    - reference_id: PMID:17525340
      supporting_text: Both Abraxas and RAP80 were required for DNA damage resistance, G(2)-M checkpoint
        control, and DNA repair.
    - reference_id: PMID:19261748
      supporting_text: a stable complex containing MERIT40 acts early in DNA damage response and regulates
        damage-dependent BRCA1 localization
- term:
    id: GO:0006302
    label: double-strand break repair
  evidence_type: IMP
  original_reference_id: PMID:19261748
  qualifier: involved_in
  review:
    summary: >-
      Core biological process. ABRAXAS1 is required for efficient DNA double-strand break repair through BRCA1-A
      recruitment and ubiquitin-dependent damage-site signaling.
    action: ACCEPT
    reason: >-
      Loss/depletion experiments in the original ABRAXAS1/CCDC98 papers support DNA repair and DNA damage resistance.
      The PN-projected broader DNA repair term is already entailed by this annotation.
    additional_reference_ids:
    - file:projects/PROTEOSTASIS/reports/pn_projection/pn_projected_gene_go_summary.tsv
    supported_by:
    - reference_id: PMID:17525340
      supporting_text: Both Abraxas and RAP80 were required for DNA damage resistance, G(2)-M checkpoint
        control, and DNA repair.
    - reference_id: PMID:19261748
      supporting_text: a stable complex containing MERIT40 acts early in DNA damage response and regulates
        damage-dependent BRCA1 localization
- term:
    id: GO:0010212
    label: response to ionizing radiation
  evidence_type: IMP
  original_reference_id: PMID:17525340
  qualifier: involved_in
  review:
    summary: >-
      Supported but non-core phenotype/context annotation. Ionizing radiation is the experimental damage stimulus
      used to reveal ABRAXAS1 DNA damage-response function.
    action: KEEP_AS_NON_CORE
    reason: >-
      The IR response annotations should be retained as useful experimental context, but the core process is DNA
      double-strand break repair/checkpoint signaling through BRCA1-A.
    supported_by:
    - reference_id: PMID:18077395
      supporting_text: the entire Brca1 A complex to DNA-damage foci
    - reference_id: PMID:19261749
      supporting_text: required for resistance to ionizing radiation
- term:
    id: GO:0010212
    label: response to ionizing radiation
  evidence_type: IMP
  original_reference_id: PMID:17643121
  qualifier: involved_in
  review:
    summary: >-
      Supported but non-core phenotype/context annotation. Ionizing radiation is the experimental damage stimulus
      used to reveal ABRAXAS1 DNA damage-response function.
    action: KEEP_AS_NON_CORE
    reason: >-
      The IR response annotations should be retained as useful experimental context, but the core process is DNA
      double-strand break repair/checkpoint signaling through BRCA1-A.
    supported_by:
    - reference_id: PMID:18077395
      supporting_text: the entire Brca1 A complex to DNA-damage foci
    - reference_id: PMID:19261749
      supporting_text: required for resistance to ionizing radiation
- term:
    id: GO:0010212
    label: response to ionizing radiation
  evidence_type: IMP
  original_reference_id: PMID:19261748
  qualifier: involved_in
  review:
    summary: >-
      Supported but non-core phenotype/context annotation. Ionizing radiation is the experimental damage stimulus
      used to reveal ABRAXAS1 DNA damage-response function.
    action: KEEP_AS_NON_CORE
    reason: >-
      The IR response annotations should be retained as useful experimental context, but the core process is DNA
      double-strand break repair/checkpoint signaling through BRCA1-A.
    supported_by:
    - reference_id: PMID:18077395
      supporting_text: the entire Brca1 A complex to DNA-damage foci
    - reference_id: PMID:19261749
      supporting_text: required for resistance to ionizing radiation
- term:
    id: GO:0031593
    label: polyubiquitin modification-dependent protein binding
  evidence_type: IDA
  original_reference_id: PMID:19261749
  qualifier: enables
  review:
    summary: >-
      Core molecular function. ABRAXAS1 is part of a BRCA1-A/RAP80 complex that recognizes ubiquitinated damage-site
      chromatin and has polyubiquitin-binding capacity.
    action: ACCEPT
    reason: >-
      The term captures the ubiquitin-recognition side of ABRAXAS1 biology better than generic protein binding.
      It should be retained for both direct IDA and IBA evidence.
    supported_by:
    - reference_id: PMID:19261749
      supporting_text: four members of the BRCA1-A complex possess a polyubiquitin chain-binding capability
    - reference_id: PMID:20656689
      supporting_text: RAP80, in turn, is recruited to DSBs through its tandem ubiquitin-interacting motifs
        (UIMs) ( 6 , 14 – 16 ), which specifically recognize K63-Ub chains
- term:
    id: GO:0045739
    label: positive regulation of DNA repair
  evidence_type: IMP
  original_reference_id: PMID:17525340
  qualifier: involved_in
  review:
    summary: >-
      Core regulatory process. ABRAXAS1 positively supports DNA repair by assembling/stabilizing the RAP80-BRCA1-A
      complex at DNA damage sites.
    action: ACCEPT
    reason: >-
      The evidence supports a positive role in DNA repair through BRCA1 localization, complex integrity, and BRCC36-associated
      ubiquitin editing rather than direct DNA repair catalysis.
    supported_by:
    - reference_id: PMID:17525340
      supporting_text: Both Abraxas and RAP80 were required for DNA damage resistance, G(2)-M checkpoint
        control, and DNA repair.
    - reference_id: PMID:19261748
      supporting_text: a stable complex containing MERIT40 acts early in DNA damage response and regulates
        damage-dependent BRCA1 localization
    - reference_id: PMID:20656689
      supporting_text: Abraxas and BRCC45 were essential for BRCC36 DUB activity within the RAP80 complex
- term:
    id: GO:0045739
    label: positive regulation of DNA repair
  evidence_type: IMP
  original_reference_id: PMID:19261748
  qualifier: involved_in
  review:
    summary: >-
      Core regulatory process. ABRAXAS1 positively supports DNA repair by assembling/stabilizing the RAP80-BRCA1-A
      complex at DNA damage sites.
    action: ACCEPT
    reason: >-
      The evidence supports a positive role in DNA repair through BRCA1 localization, complex integrity, and BRCC36-associated
      ubiquitin editing rather than direct DNA repair catalysis.
    supported_by:
    - reference_id: PMID:17525340
      supporting_text: Both Abraxas and RAP80 were required for DNA damage resistance, G(2)-M checkpoint
        control, and DNA repair.
    - reference_id: PMID:19261748
      supporting_text: a stable complex containing MERIT40 acts early in DNA damage response and regulates
        damage-dependent BRCA1 localization
    - reference_id: PMID:20656689
      supporting_text: Abraxas and BRCC45 were essential for BRCC36 DUB activity within the RAP80 complex
- term:
    id: GO:0070531
    label: BRCA1-A complex
  evidence_type: IDA
  original_reference_id: PMID:17525340
  qualifier: part_of
  review:
    summary: >-
      Core complex membership. ABRAXAS1 is a BRCA1-A complex subunit that organizes BRCA1, UIMC1/RAP80, BRCC3/BRCC36,
      BABAM proteins, and related DDR functions.
    action: ACCEPT
    reason: >-
      Multiple primary studies and Reactome support ABRAXAS1/FAM175A as a BRCA1-A complex component. This is more
      precise than the PN-projected generic ubiquitin-ligase-complex bucket.
    additional_reference_ids:
    - file:projects/PROTEOSTASIS/reports/pn_projection/pn_projected_gene_go_summary.tsv
    - file:projects/PROTEOSTASIS/mappings/ubiquitin_proteasome_system.yaml
    supported_by:
    - reference_id: PMID:19261749
      supporting_text: Proteomic analysis revealed that NBA1 is a component of the BRCA1 A complex, which also
        contains Brca1/Bard1, Abra1, RAP80, BRCC36, and BRE.
    - reference_id: Reactome:R-HSA-5683385
      supporting_text: Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called
        BRCA1-A complex at DNA DSBs
- term:
    id: GO:0070531
    label: BRCA1-A complex
  evidence_type: IDA
  original_reference_id: PMID:19261746
  qualifier: part_of
  review:
    summary: >-
      Core complex membership. ABRAXAS1 is a BRCA1-A complex subunit that organizes BRCA1, UIMC1/RAP80, BRCC3/BRCC36,
      BABAM proteins, and related DDR functions.
    action: ACCEPT
    reason: >-
      Multiple primary studies and Reactome support ABRAXAS1/FAM175A as a BRCA1-A complex component. This is more
      precise than the PN-projected generic ubiquitin-ligase-complex bucket.
    additional_reference_ids:
    - file:projects/PROTEOSTASIS/reports/pn_projection/pn_projected_gene_go_summary.tsv
    - file:projects/PROTEOSTASIS/mappings/ubiquitin_proteasome_system.yaml
    supported_by:
    - reference_id: PMID:19261749
      supporting_text: Proteomic analysis revealed that NBA1 is a component of the BRCA1 A complex, which also
        contains Brca1/Bard1, Abra1, RAP80, BRCC36, and BRE.
    - reference_id: Reactome:R-HSA-5683385
      supporting_text: Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called
        BRCA1-A complex at DNA DSBs
- term:
    id: GO:0070531
    label: BRCA1-A complex
  evidence_type: IDA
  original_reference_id: PMID:19261748
  qualifier: part_of
  review:
    summary: >-
      Core complex membership. ABRAXAS1 is a BRCA1-A complex subunit that organizes BRCA1, UIMC1/RAP80, BRCC3/BRCC36,
      BABAM proteins, and related DDR functions.
    action: ACCEPT
    reason: >-
      Multiple primary studies and Reactome support ABRAXAS1/FAM175A as a BRCA1-A complex component. This is more
      precise than the PN-projected generic ubiquitin-ligase-complex bucket.
    additional_reference_ids:
    - file:projects/PROTEOSTASIS/reports/pn_projection/pn_projected_gene_go_summary.tsv
    - file:projects/PROTEOSTASIS/mappings/ubiquitin_proteasome_system.yaml
    supported_by:
    - reference_id: PMID:19261749
      supporting_text: Proteomic analysis revealed that NBA1 is a component of the BRCA1 A complex, which also
        contains Brca1/Bard1, Abra1, RAP80, BRCC36, and BRE.
    - reference_id: Reactome:R-HSA-5683385
      supporting_text: Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called
        BRCA1-A complex at DNA DSBs
- term:
    id: GO:0070531
    label: BRCA1-A complex
  evidence_type: IDA
  original_reference_id: PMID:19261749
  qualifier: part_of
  review:
    summary: >-
      Core complex membership. ABRAXAS1 is a BRCA1-A complex subunit that organizes BRCA1, UIMC1/RAP80, BRCC3/BRCC36,
      BABAM proteins, and related DDR functions.
    action: ACCEPT
    reason: >-
      Multiple primary studies and Reactome support ABRAXAS1/FAM175A as a BRCA1-A complex component. This is more
      precise than the PN-projected generic ubiquitin-ligase-complex bucket.
    additional_reference_ids:
    - file:projects/PROTEOSTASIS/reports/pn_projection/pn_projected_gene_go_summary.tsv
    - file:projects/PROTEOSTASIS/mappings/ubiquitin_proteasome_system.yaml
    supported_by:
    - reference_id: PMID:19261749
      supporting_text: Proteomic analysis revealed that NBA1 is a component of the BRCA1 A complex, which also
        contains Brca1/Bard1, Abra1, RAP80, BRCC36, and BRE.
    - reference_id: Reactome:R-HSA-5683385
      supporting_text: Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called
        BRCA1-A complex at DNA DSBs
references:
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping,
    accompanied by conservative changes to GO terms applied by UniProt
  findings: []
- id: GO_REF:0000052
  title: Gene Ontology annotation based on curation of immunofluorescence data
  findings: []
- id: PMID:17525340
  title: Abraxas and RAP80 form a BRCA1 protein complex required for the DNA damage response.
  findings:
  - statement: ABRAXAS1/Abraxas binds BRCA1 BRCT repeats and RAP80, and is required for DNA damage resistance,
      G2/M checkpoint control, and DNA repair.
    supporting_text: Abraxas and RAP80 were required for DNA damage resistance, G(2)-M checkpoint control, and
      DNA repair.
    reference_section_type: ABSTRACT
- id: PMID:17643121
  title: CCDC98 targets BRCA1 to DNA damage sites.
  findings: []
- id: PMID:18077395
  title: Ubc13/Rnf8 ubiquitin ligases control foci formation of the Rap80/Abraxas/Brca1/Brcc36 complex in
    response to DNA damage.
  findings: []
- id: PMID:19261746
  title: MERIT40 controls BRCA1-Rap80 complex integrity and recruitment to DNA double-strand breaks.
  findings: []
- id: PMID:19261748
  title: MERIT40 facilitates BRCA1 localization and DNA damage repair.
  findings:
  - statement: CCDC98/ABRAXAS1 is a central component for assembly of the RAP80-containing BRCA1-A complex at
      DNA damage sites.
    supporting_text: CCDC98 as the central component that facilitates the assembly of this protein complex
    reference_section_type: DISCUSSION
- id: PMID:19261749
  title: NBA1, a new player in the Brca1 A complex, is required for DNA damage resistance and checkpoint
    control.
  findings: []
- id: PMID:19615732
  title: Defining the human deubiquitinating enzyme interaction landscape.
  findings: []
- id: PMID:20656689
  title: Differential regulation of JAMM domain deubiquitinating enzyme activity within the RAP80 complex.
  findings:
  - statement: ABRAXAS1 is required for BRCC36 DUB activity in the RAP80/BRCA1-A complex context, but is not
      itself the catalytic DUB.
    supporting_text: Abraxas and BRCC45 were essential for BRCC36 DUB activity within the RAP80 complex
    reference_section_type: ABSTRACT
- id: PMID:22369660
  title: 'BRCA1 tumor suppressor network: focusing on its tail.'
  findings: []
- id: PMID:29656893
  title: DNA Repair Network Analysis Reveals Shieldin as a Key Regulator of NHEJ and PARP Inhibitor
    Sensitivity.
  findings: []
- id: PMID:34591612
  title: A protein interaction landscape of breast cancer.
  findings: []
- id: PMID:35156780
  title: CFTR interactome mapping using the mammalian membrane two-hybrid high-throughput screening system.
  findings: []
- id: PMID:36012204
  title: Differential CFTR-Interactome Proximity Labeling Procedures Identify Enrichment in Multiple SLC
    Transporters.
  findings: []
- id: PMID:39009827
  title: Proteome-scale characterisation of motif-based interactome rewiring by disease mutations.
  full_text_unavailable: true
  findings:
  - statement: ABRAXAS1 contains a functional nuclear localization signal around Arg361; the
      breast-cancer-associated R361Q mutation weakens importin/karyopherin binding approximately
      tenfold and increases cytoplasmic localization, providing a molecular basis for impaired
      nuclear import of the BRCA1-A complex.
- id: Reactome:R-HSA-5683384
  title: UIMC1 and FAM175A bind DNA DSBs
  findings: []
- id: Reactome:R-HSA-5683385
  title: Formation of BRCA1-A complex at DNA DSBs
  findings: []
- id: Reactome:R-HSA-5683735
  title: CHEK2 is recruited to DNA DSBs
  findings: []
- id: Reactome:R-HSA-5683801
  title: CHEK2 phosphorylates BRCA1
  findings: []
- id: Reactome:R-HSA-5684052
  title: PIAS4 SUMOylates MDC1
  findings: []
- id: Reactome:R-HSA-5684071
  title: RNF4 ubiquitinates MDC1
  findings: []
- id: Reactome:R-HSA-5686685
  title: RIF1 and PAX1IP bind TP53BP1 at DNA DSBs
  findings: []
- id: Reactome:R-HSA-5691411
  title: BRCA1-A complex deubiquitinates K63polyUb-histone H2A
  findings: []
- id: Reactome:R-HSA-5693551
  title: Phosphorylation of BRCA1-A complex at multiple sites by ATM
  findings: []
- id: Reactome:R-HSA-69891
  title: Phosphorylation and activation of CHEK2 by ATM
  findings: []
- id: file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
  title: ABRAXAS1 UniProtKB record
  findings: []
- id: file:human/ABRAXAS1/ABRAXAS1-notes.md
  title: ABRAXAS1 manual review notes and failed deep-research provenance
  findings: []
- id: file:projects/PROTEOSTASIS/reports/pn_projection/pn_projected_gene_go_summary.tsv
  title: Proteostasis PN projected GO summary for ABRAXAS1
  findings: []
- id: file:projects/PROTEOSTASIS/mappings/ubiquitin_proteasome_system.yaml
  title: Proteostasis ubiquitin proteasome system mapping file
  findings: []
- id: file:interpro/panther/PTHR31728/PTHR31728-entries.csv
  title: PANTHER PTHR31728 reviewed protein members
  findings: []
core_functions:
- molecular_function:
    id: GO:0031593
    label: polyubiquitin modification-dependent protein binding
  description: >-
    ABRAXAS1 is a scaffold and ubiquitin-recognition subunit of the nuclear BRCA1-A/RAP80 complex. It helps assemble
    BRCA1, UIMC1/RAP80, BRCC3/BRCC36, BABAM proteins, and related partners at ubiquitinated DNA double-strand break
    sites, thereby supporting BRCA1 recruitment, BRCC36-dependent K63-ubiquitin signal editing, DNA repair, and
    G2/M DNA damage checkpoint signaling.
  directly_involved_in:
  - id: GO:0006302
    label: double-strand break repair
  - id: GO:0045739
    label: positive regulation of DNA repair
  - id: GO:0007095
    label: mitotic G2 DNA damage checkpoint signaling
  locations:
  - id: GO:0005634
    label: nucleus
  - id: GO:0005654
    label: nucleoplasm
  in_complex:
    id: GO:0070531
    label: BRCA1-A complex
  supported_by:
  - reference_id: PMID:17525340
    supporting_text: Abraxas and RAP80 were required for DNA damage resistance, G(2)-M checkpoint control, and
      DNA repair.
  - reference_id: PMID:19261748
    supporting_text: CCDC98 as the central component that facilitates the assembly of this protein complex
  - reference_id: PMID:19261749
    supporting_text: four members of the BRCA1-A complex possess a polyubiquitin chain-binding capability
  - reference_id: PMID:20656689
    supporting_text: Abraxas and BRCC45 were essential for BRCC36 DUB activity within the RAP80 complex
  - reference_id: Reactome:R-HSA-5683385
    supporting_text: Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A
      complex at DNA DSBs
  - reference_id: file:human/ABRAXAS1/ABRAXAS1-uniprot.txt
    supporting_text: Involved in DNA damage response and double-strand break (DSB) repair.
proposed_new_terms: []
suggested_questions:
- question: Should GO curation represent ABRAXAS1 only as part of the BRCA1-A complex, or is there enough
    evidence to annotate ABRAXAS1 to a broader ubiquitin ligase complex term despite its scaffold/DUB-support
    role?
  experts:
  - Wang B
  - Greenberg RA
  - Elledge SJ
- question: Given evidence that ABRAXAS1 truncations shift BRCA1 partitioning toward BRCA1-C and derepress
    mutagenic repair (SSA/MMEJ) without impairing HR, should ABRAXAS1 carry a negative-regulation annotation
    for low-fidelity double-strand break repair pathways (e.g. single-strand annealing) in addition to its
    positive role in DNA repair?
  experts:
  - Wiesmuller L
  - Pylkas K
- question: Is the reported RNA-dependent / direct RNA-binding behavior of ABRAXAS1 (R-DeeP and iCLIP2 in a
    single lung-cancer cell line) reproducible and functionally meaningful, or a cell-line-specific
    high-throughput artifact, before any RNA-binding annotation is considered?
  experts:
  - Diederichs S
suggested_experiments:
- hypothesis: The PANTHER-derived spindle and microtubule annotations are ABRAXAS2/paralog-specific and do not
    apply to ABRAXAS1.
  description: Compare ABRAXAS1 and ABRAXAS2 depletion or rescue in synchronized human cells using spindle
    assembly, kinetochore-microtubule attachment, and DNA damage-response readouts in the same experimental
    system.
  experiment_type: comparative cell biology
- hypothesis: ABRAXAS1 restrains end resection and mutagenic double-strand break repair (single-strand
    annealing / microhomology-mediated end joining) by sequestering BRCA1 in the BRCA1-A complex, rather than
    simply promoting homologous recombination.
  description: Use chromosomally integrated DSB-repair reporters (HR, NHEJ, MMEJ, SSA) in cells expressing
    wild-type ABRAXAS1 versus C-terminal SPTF-motif and BRCC36-interaction truncation variants, measuring
    pathway-frequency shifts and end-resection markers (RPA, pRPA32, MRE11) to test pathway-choice control.
  experiment_type: DSB-repair pathway reporter assay