DDA1

UniProt ID: Q9BW61
Organism: Homo sapiens
Review Status: COMPLETE
πŸ“ Provide Detailed Feedback

Gene Description

DDA1 (DET1- and DDB1-associated protein 1) is a small, evolutionarily conserved subunit shared by numerous CUL4-RING (CRL4) E3 ubiquitin ligase complexes. It is an integral, core component of DCX/CRL4 complexes built on a core of DDB1, cullin-4 (CUL4A or CUL4B) and RBX1, where it functions as a scaffolding subunit that wraps around DDB1 and the substrate receptor (DCAF) to stabilize the assembled ligase and promote efficient, processive substrate ubiquitination. DDA1 is not itself a substrate receptor and does not provide the catalytic RING; rather it acts as an accessory/stabilizing module that rigidifies the complex and positions the substrate for ubiquitin transfer. It engages DDB1 with high affinity (Kd in the low-nanomolar range) through a conserved extreme N-terminal segment (approximately the first 28 residues) that docks into a groove on the BPA beta-propeller of DDB1, anchoring DDA1 within the assembled ligase. It has been structurally and biochemically characterized as part of the DDB1-DCAF15-DDA1 ligase that mediates aryl-sulfonamide (indisulam/E7820)-induced neosubstrate degradation of the splicing factor RBM39 (and its paralog RBM23), and it is also part of the DDD core complex (DET1-DDA1-DDB1) that recruits UBE2E-family E2 enzymes. DDA1 is additionally an integral, structurally resolved component of the CRL4(CSA) ligase, where it modestly stabilizes the CSA-DDB1 module and helps coordinate the ubiquitination dynamics that drive transcription-coupled nucleotide excision repair at RNA polymerase II stalled on DNA lesions. Through its presence across many CRL4 complexes DDA1 broadly supports CUL4-dependent protein polyubiquitination and proteasomal degradation, with downstream consequences for diverse substrates and pathways. It localizes to the nucleus where most CRL4 complexes act.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0080008 Cul4-RING E3 ubiquitin ligase complex
IBA
GO_REF:0000033
ACCEPT
Summary: Phylogenetic assignment of DDA1 as part of a CUL4-RING E3 ubiquitin ligase complex, its core role as a shared stabilizing subunit.
Reason: Core complex membership; DDA1 is an integral component of numerous DCX/CRL4 ligases; supported experimentally and conserved.
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes
GO:0032434 regulation of proteasomal ubiquitin-dependent protein catabolic process
IEA
GO_REF:0000002
ACCEPT
Summary: InterPro-based assignment of involvement in regulating proteasomal ubiquitin-dependent protein catabolism, consistent with DDA1 enhancing CRL4-mediated substrate degradation.
Reason: Correct; as a stabilizing subunit DDA1 promotes efficient CRL4-mediated ubiquitination and subsequent proteasomal degradation of substrates.
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
which mediate the ubiquitination and subsequent proteasomal degradation of target proteins
GO:0005515 protein binding
IPI
PMID:20562859
Network organization of the human autophagy system.
KEEP AS NON CORE
Summary: Interaction with DDB1 (Q16531) from an autophagy-system interactome study. Bare protein binding is uninformative.
Reason: Real DDB1 interaction (core complex partner) but bare protein binding is uninformative; captured by complex membership.
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
which consist of a core of DDB1, cullin-4 (CUL4A or CUL4B), DDA1 and RBX1
GO:0005515 protein binding
IPI
PMID:25416956
A proteome-scale map of the human interactome network.
KEEP AS NON CORE
Summary: Interactions (Q6RW13, Q96DZ9/DCAF15) from a proteome-scale interactome study. Bare protein binding is uninformative.
Reason: High-throughput interactions including DCAF15 (a CRL4 substrate receptor DDA1 stabilizes), but bare protein binding is uninformative.
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
Component of the DCX(DCAF15) complex, also named CLR4(DCAF15) complex, composed of DCAF15, DDB1, cullin-4 (CUL4A or CUL4B), DDA1 and RBX1
GO:0005515 protein binding
IPI
PMID:30564455
Structural insights into DDA1 function as a core component o...
KEEP AS NON CORE
Summary: Interaction with DDB1 (Q16531) from the structural study of DDA1 as a core component of CRL4-DDB1. The DDB1 contact is mediated by a conserved N-terminal segment binding the DDB1 BPA propeller with low-nanomolar affinity. Bare protein binding is uninformative.
Reason: Real, functionally central DDB1 interaction underpinning DDA1's scaffolding role, but bare protein binding is uninformative; captured by complex membership. The specific structural mechanism (N-terminal anchor on the DDB1 BPA propeller) is recorded in the falcon findings.
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
acts as a scaffolding subunit required to stabilize the complex
file:human/DDA1/DDA1-deep-research-falcon.md
Shabek et al. mapped DDB1 binding to a conserved **N-terminal 28-aa segment** (DDA1-NT), solved the **DDB1–DDA1-NT crystal structure at ~3.1 Γ…**, and localized binding to a groove on the **BPA propeller** of DDB1
GO:0005515 protein binding
IPI
PMID:32296183
A reference map of the human binary protein interactome.
KEEP AS NON CORE
Summary: Interactions (Q8IZV5, Q96DZ9-2/DCAF15 isoform, Q96KN3) from a binary interactome reference map. Bare protein binding is uninformative.
Reason: High-throughput interactome; bare protein binding is uninformative.
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes
GO:0005515 protein binding
IPI
PMID:32814053
Interactome Mapping Provides a Network of Neurodegenerative ...
KEEP AS NON CORE
Summary: Interaction (O60260-5, PARK2/parkin isoform) from a neurodegeneration interactome study. Bare protein binding is uninformative.
Reason: High-throughput interactome; bare protein binding is uninformative and not a core function.
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes
GO:0005515 protein binding
IPI
PMID:35271311
OpenCell: Endogenous tagging for the cartography of human ce...
KEEP AS NON CORE
Summary: Interaction with DDB1 (Q16531) from the OpenCell endogenous-tagging interactome. Bare protein binding is uninformative.
Reason: Real DDB1 interaction but bare protein binding is uninformative; captured by complex membership.
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
which consist of a core of DDB1, cullin-4 (CUL4A or CUL4B), DDA1 and RBX1
GO:0016567 protein ubiquitination
IEA
GO_REF:0000041
ACCEPT
Summary: UniPathway-derived general protein-ubiquitination process, consistent with DDA1's role in CRL4-mediated ubiquitination.
Reason: Correct; DDA1 contributes to CRL4-mediated protein ubiquitination as a stabilizing subunit.
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
PATHWAY: Protein modification; protein ubiquitination.
GO:0031464 Cul4A-RING E3 ubiquitin ligase complex
IPI
PMID:31693891
Aryl Sulfonamides Degrade RBM39 and RBM23 by Recruitment to ...
ACCEPT
Summary: Physical-interaction (ComplexPortal) evidence that DDA1 is part of the CUL4A-RING (CRL4A-DCAF15) ligase complex. Core complex membership.
Reason: Core complex membership with experimental support; DDA1 is part of CRL4(DCAF15).
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
composed of DCAF15, DDB1, cullin-4 (CUL4A or CUL4B), DDA1 and RBX1
GO:0031465 Cul4B-RING E3 ubiquitin ligase complex
NAS
PMID:31452512
Systematic identification of cancer cell vulnerabilities to ...
ACCEPT
Summary: Author statement (ComplexPortal) that DDA1 is part of the CUL4B-RING (CRL4B-DCAF15) ligase complex. Core complex membership.
Reason: Core complex membership; DDA1 is a shared subunit of CUL4A- and CUL4B-based CRL4(DCAF15) ligases.
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
composed of DCAF15, DDB1, cullin-4 (CUL4A or CUL4B), DDA1 and RBX1
GO:0032814 regulation of natural killer cell activation
NAS
PMID:31452512
Systematic identification of cancer cell vulnerabilities to ...
KEEP AS NON CORE
Summary: Author statement linking the CRL4-DCAF15 ligase (of which DDA1 is the stabilizing subunit) to regulation of NK-cell-mediated immune surveillance; DCAF15 disruption sensitizes cancer cells to NK clearance.
Reason: A real but indirect, context-specific role mediated through the DCAF15 substrate receptor; peripheral to DDA1's core CRL4-stabilizing function.
Supporting Evidence:
PMID:31452512
the ubiquitin ligase substrate adaptor DCAF15 strongly sensitized cancer cells to NK-mediated clearance
GO:0000209 protein polyubiquitination
IMP
PMID:31686031
Structural complementarity facilitates E7820-mediated degrad...
ACCEPT
Summary: Mutant-phenotype evidence that DDA1, within the DDB1-DCAF15-DDA1 core ligase, supports polyubiquitination (E7820-mediated RBM39 degradation). Core process role.
Reason: Supported; the DDB1-DCAF15-DDA1 ligase polyubiquitinates RBM39, with DDA1 stabilizing the DCAF15 fold.
Supporting Evidence:
PMID:31686031
We show that DCAF15 adopts a new fold stabilized by DDA1
GO:0080008 Cul4-RING E3 ubiquitin ligase complex
IDA
PMID:28302793
Anticancer sulfonamides target splicing by inducing RBM39 de...
ACCEPT
Summary: Direct evidence that DDA1 is part of a CUL4-RING (CRL4-DCAF15) E3 ligase complex mediating RBM39 degradation. Core complex membership.
Reason: Core complex membership with direct support.
Supporting Evidence:
PMID:28302793
indisulam promotes the recruitment of RBM39 (RNA binding motif protein 39) to the CUL4-DCAF15 E3 ubiquitin ligase
GO:0080008 Cul4-RING E3 ubiquitin ligase complex
IDA
PMID:31686031
Structural complementarity facilitates E7820-mediated degrad...
ACCEPT
Summary: Direct (cryo-EM) evidence that DDA1 is part of the DDB1-DCAF15-DDA1 core CRL4 ligase complex. Core complex membership.
Reason: Core complex membership with direct structural support.
Supporting Evidence:
PMID:31686031
the cryo-EM structure of the DDB1-DCAF15-DDA1 core ligase complex bound to RBM39
GO:0005515 protein binding
IPI
PMID:16949367
A family of diverse Cul4-Ddb1-interacting proteins includes ...
KEEP AS NON CORE
Summary: Interactions with DDB1, CUL4A and CUL4B from the DCAF-family study; establishes DDA1 association with the CUL4-DDB1 core. Bare protein binding is uninformative.
Reason: Real core-complex interactions but bare protein binding is uninformative; captured by complex membership.
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
which consist of a core of DDB1, cullin-4 (CUL4A or CUL4B), DDA1 and RBX1
GO:0080008 Cul4-RING E3 ubiquitin ligase complex
IDA
PMID:16949367
A family of diverse Cul4-Ddb1-interacting proteins includes ...
ACCEPT
Summary: Direct evidence (DCAF-family study) that DDA1 is part of a CUL4-RING E3 ligase complex. Core complex membership.
Reason: Core complex membership with direct support.
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes
GO:0005654 nucleoplasm
TAS
Reactome:R-HSA-8952638
ACCEPT
Summary: Reactome curation of DDA1 nucleoplasmic localization within a CRL4 neddylation reaction. Consistent with the nuclear site of CRL4 action.
Reason: Correct localization; CRL4 complexes containing DDA1 act in the nucleus.
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes
GO:0005654 nucleoplasm
TAS
Reactome:R-HSA-8952639
ACCEPT
Summary: Reactome curation of DDA1 nucleoplasmic localization within a CRL4 neddylation reaction.
Reason: Correct localization; redundant with the other nucleoplasm annotations.
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes
GO:0005654 nucleoplasm
TAS
Reactome:R-HSA-8955245
ACCEPT
Summary: Reactome curation of DDA1 nucleoplasmic localization within a CRL4 regulation reaction (CAND1 binds CRL4).
Reason: Correct localization; redundant with the other nucleoplasm annotations.
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes
GO:0005654 nucleoplasm
TAS
Reactome:R-HSA-8955285
ACCEPT
Summary: Reactome curation of DDA1 nucleoplasmic localization within a CRL4 regulation reaction (COMMDs displace CAND1).
Reason: Correct localization; redundant with the other nucleoplasm annotations.
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes
GO:0005654 nucleoplasm
TAS
Reactome:R-HSA-8956045
ACCEPT
Summary: Reactome curation of DDA1 nucleoplasmic localization within a CRL4 regulation reaction (COP9 signalosome deneddylates CRL4).
Reason: Correct localization; redundant with the other nucleoplasm annotations.
Supporting Evidence:
file:human/DDA1/DDA1-uniprot.txt
Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes

Core Functions

Shared core scaffolding/stabilizing subunit of CUL4-RING (CRL4/DCX) E3 ubiquitin ligase complexes (DDB1-CUL4A/CUL4B-RBX1 with a DCAF receptor), where DDA1 rigidifies the assembly and the substrate receptor fold to promote efficient CRL4-mediated polyubiquitination and proteasomal degradation of substrates. DDA1 is neither the substrate receptor nor the catalytic RING.

Supporting Evidence:
  • file:human/DDA1/DDA1-uniprot.txt
    acts as a scaffolding subunit required to stabilize the complex
  • PMID:31686031
    We show that DCAF15 adopts a new fold stabilized by DDA1
  • file:human/DDA1/DDA1-deep-research-falcon.md
    Shabek et al. mapped DDB1 binding to a conserved **N-terminal 28-aa segment** (DDA1-NT), solved the **DDB1–DDA1-NT crystal structure at ~3.1 Γ…**, and localized binding to a groove on the **BPA propeller** of DDB1

As an integral component of the CRL4(CSA) ligase, DDA1 coordinates the ubiquitination dynamics that drive transcription-coupled nucleotide excision repair at RNA polymerase II stalled on DNA lesions, modestly stabilizing the CSA-DDB1 module and supporting efficient repair turnover/progression.

Supporting Evidence:
  • file:human/DDA1/DDA1-deep-research-falcon.md
    DDA1 was identified as a **CSA interactor** by single-step complex isolation/MS and shown by cryo-EM to be an **integral CRL4CSA component**; functionally, DDA1 was concluded to **coordinate ubiquitination dynamics during TC-NER** and be **required for efficient turnover/progression** of the repair process

References

Gene Ontology annotation through association of InterPro records with GO terms
Annotation inferences using phylogenetic trees
Gene Ontology annotation based on UniPathway vocabulary mapping
A family of diverse Cul4-Ddb1-interacting proteins includes Cdt2, which is required for S phase destruction of the replication factor Cdt1.
  • Defines the family of DDB1- and CUL4-associated factors (DCAFs); DDA1 associates with the CUL4-DDB1 core.
Network organization of the human autophagy system.
A proteome-scale map of the human interactome network.
Anticancer sulfonamides target splicing by inducing RBM39 degradation via recruitment to DCAF15.
  • Indisulam recruits RBM39 to the CUL4-DCAF15 E3 ligase (containing DDA1) for polyubiquitination and proteasomal degradation.
Structural insights into DDA1 function as a core component of the CRL4-DDB1 ubiquitin ligase.
  • Structural characterization of DDA1 as a core scaffolding/stabilizing component of the CRL4-DDB1 ubiquitin ligase.
Systematic identification of cancer cell vulnerabilities to natural killer cell-mediated immune surveillance.
  • DCAF15 (the substrate receptor of a CRL4 complex containing DDA1) disruption sensitizes cancer cells to NK-mediated clearance; cohesin members are endogenous DCAF15 substrates.
Structural complementarity facilitates E7820-mediated degradation of RBM39 by DCAF15.
  • Cryo-EM structure of the DDB1-DCAF15-DDA1 core ligase bound to RBM39; DCAF15 adopts a new fold stabilized by DDA1.
Aryl Sulfonamides Degrade RBM39 and RBM23 by Recruitment to CRL4-DCAF15.
  • Aryl sulfonamides recruit RBM39 and its paralog RBM23 to the CRL4-DCAF15 ligase (containing DDA1) for ubiquitination and degradation.
A reference map of the human binary protein interactome.
Interactome Mapping Provides a Network of Neurodegenerative Disease Proteins and Uncovers Widespread Protein Aggregation in Affected Brains.
OpenCell: Endogenous tagging for the cartography of human cellular organization.
file:human/DDA1/DDA1-deep-research-falcon.md
Falcon deep research report for human DDA1
  • DDA1 binds DDB1 with high affinity through a conserved extreme N-terminal segment (~first 28 residues) that docks into a groove on the BPA beta-propeller of DDB1, defining its anchoring mechanism within CRL4 ligases.
    "Shabek et al. mapped DDB1 binding to a conserved **N-terminal 28-aa segment** (DDA1-NT), solved the **DDB1–DDA1-NT crystal structure at ~3.1 Γ…**, and localized binding to a groove on the **BPA propeller** of DDB1"
  • DDA1 is best supported as a small structural/regulatory subunit of DDB1-CUL4 ligases rather than an enzyme, modulating ligase architecture and ubiquitination output in a context-dependent manner.
    "DDA1 is not an enzyme** (no independent catalytic reaction is described). Instead, it is best supported as a **small structural/regulatory subunit** of certain DDB1–CUL4 E3 ligase assemblies that can modulate ligase architecture and ubiquitination output in a **context-dependent** manner"
  • DDA1 is an integral component of CRL4(CSA) that coordinates ubiquitination dynamics during transcription-coupled nucleotide excision repair (TC-NER) and is required for efficient repair turnover/progression.
    "DDA1 was identified as a **CSA interactor** by single-step complex isolation/MS and shown by cryo-EM to be an **integral CRL4CSA component**; functionally, DDA1 was concluded to **coordinate ubiquitination dynamics during TC-NER** and be **required for efficient turnover/progression** of the repair process"
  • DDA1 provides a modest but reproducible thermal stabilization of the CSA-DDB1 module, with stabilization driven mainly by DDA1-DDB1 contacts.
    "DDA1 provided a modest, reproducible **~1 Β°C** thermal stabilization of CSA–DDB1 measured by nanoDSF, and truncation removing a CSA-interacting helix had a similar stabilization, implying stabilization is driven mainly by **DDA1–DDB1** contacts"
Reactome:R-HSA-8952638
AcM-UBE2M transfers NEDD8 to CRL4 E3 ubiquitin ligase complex
Reactome:R-HSA-8952639
NEDD8:AcM-UBE2M binds CRL4 E3 ubiquitin ligase complex
Reactome:R-HSA-8955245
CAND1 binds CRL4 E3 ubiquitin ligase in the nucleus
Reactome:R-HSA-8955285
COMMDs displace CAND1 from CRL4 E3 ubiquitin ligase complex
Reactome:R-HSA-8956045
COP9 signalosome deneddylates nuclear CRL4 E3 ubiquitin ligase complex

Suggested Questions for Experts

Q: Across the full repertoire of CRL4 complexes, which substrate receptors (DCAFs) depend most strongly on DDA1 for assembly/activity, and is DDA1 dispensable for some?

Q: Does DDA1 contribute only to complex stability and substrate positioning, or does it also influence ubiquitin-chain processivity, linkage type, or neddylation/deneddylation dynamics of CRL4 ligases?

Q: In CRL4(CSA)-dependent transcription-coupled repair, does DDA1 act primarily by stabilizing the CSA-DDB1 module, by tuning the residence time/ubiquitination progression on lesion-stalled RNA polymerase II, or both, and which TC-NER substrates (e.g., CSB, UVSSA, RNAPII) depend on DDA1 for timely turnover?

Suggested Experiments

Experiment: Compare RBM39 (and endogenous substrate) ubiquitination kinetics in reconstituted DDB1-CUL4-RBX1-DCAF complexes with and without DDA1, measuring effects on substrate affinity, ubiquitin-transfer rate, and processivity.

Experiment: Perform quantitative proteomics of DDA1-knockout versus wild-type cells to define which CRL4 substrate pools are stabilized, distinguishing DDA1-dependent from DDA1-independent CRL4 functions.

Experiment: In DDA1-depleted cells, measure TC-NER kinetics (e.g., recovery of RNA synthesis after UV, RNAPII clearance from lesions, and ubiquitination of CSB/UVSSA) to test whether DDA1 is required for efficient CRL4(CSA)-driven repair progression, and reconstitute CRL4(CSA) in vitro +/- DDA1 to dissect its effect on ubiquitination dynamics.

Deep Research

Falcon

(DDA1-deep-research-falcon.md)
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate. Falcon Edison Scientific Literature 23 citations 2 artifacts 2026-06-13T07:23:38.857286

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.

Research report: Human DDA1 (DET1- and DDB1-associated protein 1; UniProt Q9BW61) β€” functional annotation

0) Target verification and symbol disambiguation

The protein targeted here is human DDA1 (DET1- and DDB1-associated protein 1; UniProt Q9BW61), a small conserved factor that binds DDB1 and is discussed in the context of CUL4–DDB1 (CRL4) ubiquitin ligases and DET1 complexes (shabek2018structuralinsightsinto pages 1-3, pick2007mammaliandet1regulates pages 1-2). Literature using similar strings such as β€œdDA1” (a Drosophila dopamine receptor) or β€œDDA-1” (a small molecule name) does not correspond to this protein and was excluded.

1) Key concepts and definitions (current understanding)

1.1 Cullin–RING ligases (CRLs) and CRL4 architecture

Cullin–RING ligases are multi-subunit E3 ubiquitin ligases that promote substrate ubiquitination and subsequent proteasomal degradation. CRL4 complexes are built around a CUL4A/B scaffold, a RING catalytic subunit (RBX1), and the adaptor DDB1, which recruits substrate receptors (often WD40 proteins, β€œDCAFs”) (shabek2018structuralinsightsinto pages 1-3, schiffmacher2024thesmallcrl4csa pages 1-2). In CRL4 systems, accessory components can tune assembly, geometry, and/or activity.

1.2 What DDA1 is (functional definition)

DDA1 is not an enzyme (no independent catalytic reaction is described). Instead, it is best supported as a small structural/regulatory subunit of certain DDB1–CUL4 E3 ligase assemblies that can modulate ligase architecture and ubiquitination output in a context-dependent manner (pick2007mammaliandet1regulates pages 1-2, shabek2018structuralinsightsinto pages 1-3, schiffmacher2024thesmallcrl4csa pages 3-3).

2) Molecular function and binding partners (mechanistic evidence)

2.1 Core binding: DDA1 directly binds DDB1 via its N-terminus

A major, repeatedly observed biochemical feature of human DDA1 is direct binding to DDB1 through an extreme N-terminal segment.

  • Minimal binding element and interface: Shabek et al. mapped DDB1 binding to a conserved N-terminal 28-aa segment (DDA1-NT), solved the DDB1–DDA1-NT crystal structure at ~3.1 Γ…, and localized binding to a groove on the BPA propeller of DDB1 (shabek2018structuralinsightsinto pages 1-3, shabek2018structuralinsightsinto pages 3-4). Key residues contributing to binding include Pro9, Asn15, Phe16, Arg18, Phe19 (shabek2018structuralinsightsinto pages 3-4).
  • Affinity: Bio-layer interferometry reported Kd ~45 nM for DDA1-NT binding to DDB1 (shabek2018structuralinsightsinto pages 1-3). A separate structural review summarizing additional biochemical results reports full-length DDA1 Kd β‰ˆ 28 nM vs DDA1-Nt Kd β‰ˆ 663 nM, implying additional contacts outside residues 1–28 can strengthen binding (ruble2019crl3andcrl4a pages 36-40).

These findings strongly support that DDA1’s primary biochemical role is as a high-affinity DDB1-binding module that integrates into CRL4 assemblies (shabek2018structuralinsightsinto pages 1-3, shabek2018structuralinsightsinto pages 3-4).

2.2 Complex membership: DDA1 in DET1–DDB1–DDA1 (β€œDDD”) and in CRL4CSA

  • DDD complex (DET1–DDB1–DDA1): In mammalian systems, DDA1 is reported as a stable member of a conserved DDD core complex with DET1 and DDB1 (pick2007mammaliandet1regulates pages 1-2). In this context, the DDD core recruits a canonical E2 (UBE2E family), forming a DDD–E2 assembly (pick2007mammaliandet1regulates pages 1-2).
  • CRL4CSA (TC-NER ligase): Recent work (2023–2024) identifies DDA1 as a CSA-interacting factor and an integral component of CRL4CSA (the CSA substrate-receptor CRL4 complex) that functions in transcription-coupled nucleotide excision repair (TC-NER) (schiffmacher2024thesmallcrl4csa pages 1-2, pines2023dda1anovel pages 5-7).

3) Pathways and biological processes

3.1 Regulation of CRL4 ubiquitin ligase activity (foundational evidence)

Pick et al. provide biochemical evidence that the DDD core complex can antagonize Cul4A-dependent polyubiquitin chain assembly in vitro, via effects on the E2 when incorporated into the DDD complex (pick2007mammaliandet1regulates pages 1-2). In cells, overexpression of DET1 (a DDD component) blocks UV-induced CDT1 degradation, consistent with negative regulation of a CRL4-dependent pathway controlling replication licensing after UV damage (pick2007mammaliandet1regulates pages 1-2).

Interpretation: DDA1 is part of a regulatory module (with DET1/DDB1/E2) that can down-modulate CRL4 ubiquitination output in certain assay contexts (pick2007mammaliandet1regulates pages 1-2).

The most direct, recent pathway-level function for human DDA1 is in TC-NER via CRL4CSA.

  • Discovery and role: DDA1 was identified as a CSA interactor by single-step complex isolation/MS and shown by cryo-EM to be an integral CRL4CSA component; functionally, DDA1 was concluded to coordinate ubiquitination dynamics during TC-NER and be required for efficient turnover/progression of the repair process (schiffmacher2024thesmallcrl4csa pages 1-2).
  • Structural/mechanistic detail: The CSA–DDB1–DDA1-containing complex was solved by cryo-EM at ~3.4 Γ…, resolving the DDA1 N-terminus and supporting a limited interface with CSA; AlphaFold2-multimer models were consistent with the cryo-EM conformation (schiffmacher2024thesmallcrl4csa pages 3-3). DDA1’s DDB1-contact in this complex involved DDA1 residues 2–75 (pines2023dda1anovel pages 5-7).
  • Biophysical effect on complex stability: DDA1 provided a modest, reproducible ~1 Β°C thermal stabilization of CSA–DDB1 measured by nanoDSF, and truncation removing a CSA-interacting helix had a similar stabilization, implying stabilization is driven mainly by DDA1–DDB1 contacts (schiffmacher2024thesmallcrl4csa pages 3-3).

A representative cryo-EM structural visualization of the CSA–DDB1–DDA1 complex is shown in extracted figure panels (schiffmacher2024thesmallcrl4csa media 97e65fd6, schiffmacher2024thesmallcrl4csa media ae42f398, schiffmacher2024thesmallcrl4csa media 9d6dd208).

4) Subcellular localization

Direct microscopy-based localization of DDA1 alone was not captured in the retrieved text excerpts. However, multiple independent lines of evidence place DDA1 functionally within nuclear DNA repair-associated CRL4 complexes:

  • DDA1 is embedded in the CRL4CSA ligase that operates at RNA polymerase II stalled at DNA lesions during TC-NER, a nuclear chromatin-associated process (schiffmacher2024thesmallcrl4csa pages 1-2, pines2023dda1anovel pages 5-7).

Accordingly, the best-supported localization inference from the available evidence is that DDA1 acts at least in part in the nucleus as a component of CRL4CSA during TC-NER (schiffmacher2024thesmallcrl4csa pages 1-2).

5) Recent developments (prioritizing 2023–2024)

5.1 2024 Nature Communications: DDA1 as a β€œsmall CRL4CSA component” that regulates TC-NER dynamics

Schiffmacher et al. (published July 2024) advance the field by (i) placing DDA1 inside the TC-NER E3 ligase at structural resolution, (ii) arguing DDA1–CSA binding is low-affinity/transient, and (iii) connecting DDA1 to dynamic ubiquitination regulation during repair (schiffmacher2024thesmallcrl4csa pages 3-3, schiffmacher2024thesmallcrl4csa pages 1-2). The work reports practical biochemical conditions for CRL4CSA in vitro ubiquitination (e.g., 1.5 Β΅M UVSSA, 0.2 Β΅M UBA1, 1 Β΅M UBE2E1, 20 Β΅M ubiquitin, 30 Β°C, 20 min) and nanoDSF conditions (e.g., 2 Β΅M protein; 20–90 Β°C ramp at 1 Β°C/min) that can be reused for reconstitution studies (schiffmacher2024thesmallcrl4csa pages 14-15).

Ubiquitination assay panels from the same article were also extracted as figure evidence (schiffmacher2024thesmallcrl4csa media 97e65fd6, schiffmacher2024thesmallcrl4csa media ae42f398, schiffmacher2024thesmallcrl4csa media 9d6dd208).

5.2 2024 assay development and tool-building for DDB1 interaction antagonists

Yong et al. (May 2024) developed fluorescence polarization peptide-displacement assays with full-length DDB1 to screen for antagonists of DDB1 interactions (drug discovery relevance for antiviral/anticancer strategies). While the authors did not observe significant affinity for DDA1-derived peptides in their FP format (β€œdata not shown”), the work provides a scalable platform and quantitative assay performance metrics (e.g., Z-factor 0.73, DMSO tolerance to 2% for 30 min) (yong2024developmentofpeptide pages 7-8). The study reports a peptide-probe affinity Kd = 68 nM (FITC-DCAF15 L49A peptide binding DDB1), illustrating the achievable assay sensitivity for DDB1-interactor interfaces in general (yong2024developmentofpeptide pages 1-2).

6) Current applications and real-world implementations

6.1 Targeted protein degradation (TPD) and molecular glues: DDA1 in DCAF15:DDA1:DDB1 complexes

DDA1 is a constitutive component of the DCAF15:DDA1:DDB1 ligase system used by sulfonamide β€œmolecular glues” (e.g., E7820, indisulam) that recruit the splicing factor RBM39 for degradation.

A 2024 native mass spectrometry (nMS) study demonstrates practical analytical workflows and reveals stoichiometric rearrangements relevant to TPD development: the DCAF15:DDA1:DDB1 complex self-associates into dimers/trimers at low salt (100 mM ammonium acetate) and shifts to single copies at higher salt (500 mM) or upon addition of molecular glue + RBM39, yielding a 1:1:1 ternary complex (jackson2024nativemassspectrometry pages 1-2). The paper also provides typical experimental concentrations (e.g., ~10 Β΅M E3 and POI; ~200 Β΅M molecular glue) that reflect current implementation practice for nMS-based TPD characterization (jackson2024nativemassspectrometry pages 1-2).

Interpretation: while DDA1 is not typically the pharmacologic β€œhandle” itself in these systems, it is a required architectural component of ligase assemblies that are actively used in therapeutic discovery workflows (jackson2024nativemassspectrometry pages 1-2).

6.2 Drug discovery aimed at DDB1 interaction surfaces

The DDA1–DDB1 interface is structurally defined at near-atomic resolution and has nanomolar affinity, supporting feasibility for rational ligand discovery that perturbs DDB1-protein interactions (shabek2018structuralinsightsinto pages 1-3, ruble2019crl3andcrl4a pages 36-40). The development of DDB1 interaction displacement assays (even when not directly capturing DDA1 peptide binding in FP format) indicates active efforts to build screening infrastructure for DDB1 interface modulators (yong2024developmentofpeptide pages 7-8, yong2024developmentofpeptide pages 1-2).

7) Expert interpretation and synthesis (authoritative analysis grounded in evidence)

A consistent theme across structural and functional studies is that DDA1’s principal role is as an auxiliary CRL4 subunit that can influence ligase assembly/stability and ubiquitination dynamics rather than acting as a substrate receptor itself (shabek2018structuralinsightsinto pages 1-3, schiffmacher2024thesmallcrl4csa pages 3-3). The reported context dependence (inhibitory effects in some reconstitutions/complex contexts, apparently neutral effects in others) suggests that DDA1’s contribution is likely mediated by geometry and dynamics of DDB1/CUL4 modules, by the particular DCAF/substrate present, and/or by additional regulatory factors (pick2007mammaliandet1regulates pages 1-2, schiffmacher2024thesmallcrl4csa pages 3-3).

In TC-NER, DDA1 appears to act as a modulator of CRL4CSA dynamics, with both structural incorporation and measurable stabilization of CSA–DDB1, aligning with a model where DDA1 helps tune the residence time and ubiquitination progression on lesion-stalled transcription complexes (schiffmacher2024thesmallcrl4csa pages 3-3, schiffmacher2024thesmallcrl4csa pages 1-2).

8) Disease associations and statistics (recently curated evidence)

OpenTargets currently lists multiple disease associations for DDA1 with modest overall scores, including (examples): neurodegenerative disease (score ~0.3696), atrial fibrillation (~0.1274), hypertension (~0.1170), neoplasm (~0.1101), and lung cancer (~0.0799), each supported by 4 evidence items in the OpenTargets snapshot returned here (OpenTargets Search: -DDA1). The OpenTargets record links to PubMed IDs including 28211159, 26942699, and 34031600 (OpenTargets Search: -DDA1).

Interpretation: these associations indicate emerging or exploratory links (genetic/functional screens/literature) rather than definitive causal roles, and should be followed up by disease-focused primary literature beyond this limited snapshot (OpenTargets Search: -DDA1).


Summary table (evidence map)

The following table consolidates identity checks, mechanisms, quantitative parameters (affinities/resolutions/assay conditions), and translational applications.

Aspect Key findings Best supporting sources Publication details
identity/domains β€’ Verified target is human DDA1 / DET1- and DDB1-associated protein 1 (UniProt Q9BW61), not Drosophila dDA1 receptor or chemical "DDA-1" β€’ Conserved DDA1 family protein and basal CRL4-associated component β€’ UniProt-consistent function in DDB1/CUL4 systems supported by multiple human studies (shabek2018structuralinsightsinto pages 1-3, pick2007mammaliandet1regulates pages 1-2) (shabek2018structuralinsightsinto pages 1-3, pick2007mammaliandet1regulates pages 1-2) 2018, Cell Discovery, https://doi.org/10.1038/s41421-018-0064-8; 2007, Molecular and Cellular Biology, https://doi.org/10.1128/mcb.02432-06
complex membership β€’ Stable member of mammalian DET1–DDB1–DDA1 (DDD) core complex β€’ Also an integral component of CRL4^CSA in TC-NER; binds CSA and DDB1 β€’ Present in DCAF15:DDA1:DDB1 ligase assemblies used by molecular glues, but not detected in CRL4^DDB2 in the cited TC-NER proteomics (pick2007mammaliandet1regulates pages 1-2, pines2023dda1anovel pages 5-7, schiffmacher2024thesmallcrl4csa pages 1-2, jackson2024nativemassspectrometry pages 1-2) (pick2007mammaliandet1regulates pages 1-2, pines2023dda1anovel pages 5-7, schiffmacher2024thesmallcrl4csa pages 1-2, jackson2024nativemassspectrometry pages 1-2) 2007, Molecular and Cellular Biology, https://doi.org/10.1128/mcb.02432-06; 2023, Research Square, https://doi.org/10.21203/rs.3.rs-3385435/v1; 2024, Nature Communications, https://doi.org/10.1038/s41467-024-50584-7; 2024, bioRxiv, https://doi.org/10.1101/2023.02.03.526954
molecular function β€’ Functions as a small structural/regulatory subunit of DDB1-CUL4 E3 ligases rather than an enzyme with its own catalytic reaction β€’ In DDD-E2 context, negatively regulates Cul4A-dependent polyubiquitin chain assembly in vitro β€’ In TC-NER, coordinates ubiquitination dynamics and supports efficient turnover/progression at stalled RNAPII (pick2007mammaliandet1regulates pages 1-2, pines2023dda1anovel pages 1-5, schiffmacher2024thesmallcrl4csa pages 1-2) (pick2007mammaliandet1regulates pages 1-2, pines2023dda1anovel pages 1-5, schiffmacher2024thesmallcrl4csa pages 1-2) 2007, Molecular and Cellular Biology, https://doi.org/10.1128/mcb.02432-06; 2023, Research Square, https://doi.org/10.21203/rs.3.rs-3385435/v1; 2024, Nature Communications, https://doi.org/10.1038/s41467-024-50584-7
structural determinants β€’ N-terminal 1–28 aa (or broader 2–75 aa in CRL4^CSA map) mediates direct DDB1 engagement β€’ DDB1-binding site lies on the BPA propeller; key residues include Pro9, Asn15, Phe16, Arg18, Phe19 β€’ Reported affinities/resolution: Kd ~45 nM for DDA1-NT by BLI; alternate summaries report FL Kd 28 nM vs NT Kd 663 nM; crystal/cryo-EM resolutions 3.1–3.4 Γ… (shabek2018structuralinsightsinto pages 1-3, shabek2018structuralinsightsinto pages 3-4, ruble2019crl3andcrl4a pages 36-40, schiffmacher2024thesmallcrl4csa pages 3-3) (shabek2018structuralinsightsinto pages 1-3, shabek2018structuralinsightsinto pages 3-4, ruble2019crl3andcrl4a pages 36-40, schiffmacher2024thesmallcrl4csa pages 3-3) 2018, Cell Discovery, https://doi.org/10.1038/s41421-018-0064-8; 2024, Nature Communications, https://doi.org/10.1038/s41467-024-50584-7
localization/compartment β€’ Functional evidence places DDA1 mainly in nuclear CRL4 complexes involved in DNA repair β€’ TC-NER role implies action at DNA damage-stalled RNA polymerase II/chromatin β€’ Direct localization evidence in retrieved texts is limited; compartment inference is strongest from CRL4^CSA structure/function rather than standalone imaging of DDA1 (pines2023dda1anovel pages 1-5, schiffmacher2024thesmallcrl4csa pages 1-2, pines2023dda1anovel pages 5-7) (pines2023dda1anovel pages 1-5, schiffmacher2024thesmallcrl4csa pages 1-2, pines2023dda1anovel pages 5-7) 2023, Research Square, https://doi.org/10.21203/rs.3.rs-3385435/v1; 2024, Nature Communications, https://doi.org/10.1038/s41467-024-50584-7
pathways/biological processes β€’ Participates in CRL4 ubiquitin ligase regulation β€’ Key human pathway link is transcription-coupled nucleotide excision repair (TC-NER), affecting ubiquitination of TC-NER factors such as RNAPII/UVSSA/CSB through CRL4^CSA context β€’ Foundational work also links DDA1-containing complexes to UV-induced CDT1 stability and broader CRL4 control (pick2007mammaliandet1regulates pages 1-2, pines2023dda1anovel pages 1-5, schiffmacher2024thesmallcrl4csa pages 1-2) (pick2007mammaliandet1regulates pages 1-2, pines2023dda1anovel pages 1-5, schiffmacher2024thesmallcrl4csa pages 1-2) 2007, Molecular and Cellular Biology, https://doi.org/10.1128/mcb.02432-06; 2023, Research Square, https://doi.org/10.21203/rs.3.rs-3385435/v1; 2024, Nature Communications, https://doi.org/10.1038/s41467-024-50584-7
recent 2023-2024 advances β€’ 2023 preprint/2024 paper established DDA1 as a CSA-interacting protein and integral CRL4^CSA component β€’ Cryo-EM of CSA–DDB1–DDA1-containing complex reached 3.4 Γ… β€’ DDA1 gave a modest but reproducible ~1 Β°C thermal stabilization of CSA-DDB1; assays used 2 Β΅M protein in nanoDSF and in vitro ubiquitination conditions including 1.5 Β΅M UVSSA, 0.2 Β΅M UBA1, 1 Β΅M UBE2E1, 20 Β΅M ubiquitin (pines2023dda1anovel pages 5-7, schiffmacher2024thesmallcrl4csa pages 3-3, schiffmacher2024thesmallcrl4csa pages 14-15, schiffmacher2024thesmallcrl4csa media 97e65fd6) (pines2023dda1anovel pages 5-7, schiffmacher2024thesmallcrl4csa pages 3-3, schiffmacher2024thesmallcrl4csa pages 14-15, schiffmacher2024thesmallcrl4csa media 97e65fd6) 2023, Research Square, https://doi.org/10.21203/rs.3.rs-3385435/v1; 2024, Nature Communications, https://doi.org/10.1038/s41467-024-50584-7
applications β€’ Drug-discovery assays now use DDB1-interaction peptides/FP displacement to find antagonists of DDB1 complexes relevant to antiviral/anticancer discovery β€’ DDA1-containing DCAF15:DDA1:DDB1 complexes are used in targeted protein degradation studies with RBM39 molecular glues (E7820, indisulam) β€’ Native MS can resolve DDA1-containing ternary complexes and stoichiometric changes, enabling practical TPD analytics (jackson2024nativemassspectrometry pages 1-2, yong2024developmentofpeptide pages 7-8, yong2024developmentofpeptide pages 1-2) (jackson2024nativemassspectrometry pages 1-2, yong2024developmentofpeptide pages 7-8, yong2024developmentofpeptide pages 1-2) 2024, bioRxiv, https://doi.org/10.1101/2023.02.03.526954; 2024, Biochemistry, https://doi.org/10.1021/acs.biochem.4c00044
quantitative statistics β€’ DDA1–DDB1 affinity: Kd ~45 nM (BLI, DDA1-NT); alternate reported values 28 nM FL and 663 nM NT β€’ Structures: 3.1 Γ… DDB1–DDA1-NT crystal; 3.4 Γ… CRL4^CSA cryo-EM β€’ Screening/TPD metrics: FITC-DCAF15 L49A Kd 68 nM, Z-factor 0.73, DCAF15:DDA1:DDB1 self-association at 100 mM ammonium acetate and dissociation/1:1:1 ternary complex at 500 mM ammonium acetate or upon MG+POI addition; OpenTargets association scores include neurodegenerative disease 0.3696, atrial fibrillation 0.1274, hypertension 0.1170, neoplasm 0.1101, lung cancer 0.0799 (shabek2018structuralinsightsinto pages 1-3, ruble2019crl3andcrl4a pages 36-40, schiffmacher2024thesmallcrl4csa pages 3-3, jackson2024nativemassspectrometry pages 1-2, yong2024developmentofpeptide pages 7-8, OpenTargets Search: -DDA1) (shabek2018structuralinsightsinto pages 1-3, ruble2019crl3andcrl4a pages 36-40, schiffmacher2024thesmallcrl4csa pages 3-3, jackson2024nativemassspectrometry pages 1-2, yong2024developmentofpeptide pages 7-8, OpenTargets Search: -DDA1) 2018, Cell Discovery, https://doi.org/10.1038/s41421-018-0064-8; 2024, Nature Communications, https://doi.org/10.1038/s41467-024-50584-7; 2024, bioRxiv, https://doi.org/10.1101/2023.02.03.526954; 2024, Biochemistry, https://doi.org/10.1021/acs.biochem.4c00044; OpenTargets platform context (OpenTargets Search: -DDA1)

Table: This table summarizes the strongest available functional annotation evidence for human DDA1 (UniProt Q9BW61), emphasizing experimentally supported complex membership, structural mechanism, TC-NER function, and translational relevance. It consolidates recent and foundational quantitative findings useful for downstream gene/protein annotation.

Key primary sources (with URLs and publication dates)

  • Pick et al., 2007-07. Molecular and Cellular Biology. β€œMammalian DET1 regulates Cul4A activity and forms stable complexes with E2 ubiquitin-conjugating enzymes.” https://doi.org/10.1128/mcb.02432-06 (pick2007mammaliandet1regulates pages 1-2)
  • Shabek et al., 2018-12. Cell Discovery. β€œStructural insights into DDA1 function as a core component of the CRL4-DDB1 ubiquitin ligase.” https://doi.org/10.1038/s41421-018-0064-8 (shabek2018structuralinsightsinto pages 1-3)
  • Pines et al., 2023-10 (preprint). Research Square. β€œDDA1, a novel factor in transcription-coupled repair, modulates CRL4CSA dynamics at DNA damage-stalled RNA polymerase II.” https://doi.org/10.21203/rs.3.rs-3385435/v1 (pines2023dda1anovel pages 5-7)
  • Schiffmacher et al., 2024-07. Nature Communications. β€œThe small CRL4CSA ubiquitin ligase component DDA1 regulates transcription-coupled repair dynamics.” https://doi.org/10.1038/s41467-024-50584-7 (schiffmacher2024thesmallcrl4csa pages 1-2)
  • Yong et al., 2024-05. Biochemistry. β€œDevelopment of Peptide Displacement Assays to Screen for Antagonists of DDB1 Interactions.” https://doi.org/10.1021/acs.biochem.4c00044 (yong2024developmentofpeptide pages 1-2)
  • Jackson & Beveridge, 2024-06 (preprint). bioRxiv. β€œNative Mass Spectrometry of Complexes Formed by Molecular Glues Reveals Stoichiometric Rearrangement of E3 Ligases.” https://doi.org/10.1101/2023.02.03.526954 (jackson2024nativemassspectrometry pages 1-2)

Figures extracted from primary literature

  • Cryo-EM structure/model and ubiquitination assay panels from Schiffmacher et al. (schiffmacher2024thesmallcrl4csa media 97e65fd6, schiffmacher2024thesmallcrl4csa media ae42f398, schiffmacher2024thesmallcrl4csa media 9d6dd208).

References

  1. (shabek2018structuralinsightsinto pages 1-3): Nitzan Shabek, James Ruble, Claire J. Waston, Kenneth C. Garbutt, Thomas R. Hinds, Ti Li, and Ning Zheng. Structural insights into dda1 function as a core component of the crl4-ddb1 ubiquitin ligase. Cell Discovery, Dec 2018. URL: https://doi.org/10.1038/s41421-018-0064-8, doi:10.1038/s41421-018-0064-8. This article has 39 citations and is from a peer-reviewed journal.

  2. (pick2007mammaliandet1regulates pages 1-2): Elah Pick, On-Sun Lau, Tomohiko Tsuge, Suchithra Menon, Yingchun Tong, Naoshi Dohmae, Scott M. Plafker, Xing Wang Deng, and Ning Wei. Mammalian det1 regulates cul4a activity and forms stable complexes with e2 ubiquitin-conjugating enzymes. Jul 2007. URL: https://doi.org/10.1128/mcb.02432-06, doi:10.1128/mcb.02432-06. This article has 72 citations and is from a domain leading peer-reviewed journal.

  3. (schiffmacher2024thesmallcrl4csa pages 1-2): Diana A. Llerena Schiffmacher, Shun-Hsiao Lee, Katarzyna W. Kliza, Arjan F. Theil, Masaki Akita, Angela Helfricht, Karel Bezstarosti, Camila Gonzalo-Hansen, Haico van Attikum, Matty Verlaan-de Vries, Alfred C. O. Vertegaal, Jan H. J. Hoeijmakers, Jurgen A. Marteijn, Hannes Lans, Jeroen A. A. Demmers, Michiel Vermeulen, Titia K. Sixma, Tomoo Ogi, Wim Vermeulen, and Alex Pines. The small crl4csa ubiquitin ligase component dda1 regulates transcription-coupled repair dynamics. Nature Communications, Jul 2024. URL: https://doi.org/10.1038/s41467-024-50584-7, doi:10.1038/s41467-024-50584-7. This article has 17 citations and is from a highest quality peer-reviewed journal.

  4. (schiffmacher2024thesmallcrl4csa pages 3-3): Diana A. Llerena Schiffmacher, Shun-Hsiao Lee, Katarzyna W. Kliza, Arjan F. Theil, Masaki Akita, Angela Helfricht, Karel Bezstarosti, Camila Gonzalo-Hansen, Haico van Attikum, Matty Verlaan-de Vries, Alfred C. O. Vertegaal, Jan H. J. Hoeijmakers, Jurgen A. Marteijn, Hannes Lans, Jeroen A. A. Demmers, Michiel Vermeulen, Titia K. Sixma, Tomoo Ogi, Wim Vermeulen, and Alex Pines. The small crl4csa ubiquitin ligase component dda1 regulates transcription-coupled repair dynamics. Nature Communications, Jul 2024. URL: https://doi.org/10.1038/s41467-024-50584-7, doi:10.1038/s41467-024-50584-7. This article has 17 citations and is from a highest quality peer-reviewed journal.

  5. (shabek2018structuralinsightsinto pages 3-4): Nitzan Shabek, James Ruble, Claire J. Waston, Kenneth C. Garbutt, Thomas R. Hinds, Ti Li, and Ning Zheng. Structural insights into dda1 function as a core component of the crl4-ddb1 ubiquitin ligase. Cell Discovery, Dec 2018. URL: https://doi.org/10.1038/s41421-018-0064-8, doi:10.1038/s41421-018-0064-8. This article has 39 citations and is from a peer-reviewed journal.

  6. (ruble2019crl3andcrl4a pages 36-40): J Ruble. Crl3 and crl4 are functionally diverse ubiquitination complexes that regulate fundamental cell processes from human dna damage repair to plant pathogen …. Unknown journal, 2019.

  7. (pines2023dda1anovel pages 5-7): Alex Pines, Diana Llerena Schiffmacher, Shun-Hsiao Lee, Katarzyna Kliza, Arjan Theil, Masaki Akita, Angela Helfricht, Karel Bezstarosti, Camila Gonzalo-Hansen, Haico van Attikum, Matty Verlaan-de Vries, Alfred Vertegaal, Jan Hoeijmakers, Jurgen Marteijn, Hannes Lans, Jeroen Demmers, Michiel Vermeulen, Titia Sixma, Tomoo Ogi, and Wim Vermeulen. Dda1, a novel factor in transcription-coupled repair, modulates crl4csa dynamics at dna damage-stalled rna polymerase ii. Research Square, Oct 2023. URL: https://doi.org/10.21203/rs.3.rs-3385435/v1, doi:10.21203/rs.3.rs-3385435/v1. This article has 4 citations.

  8. (schiffmacher2024thesmallcrl4csa media 97e65fd6): Diana A. Llerena Schiffmacher, Shun-Hsiao Lee, Katarzyna W. Kliza, Arjan F. Theil, Masaki Akita, Angela Helfricht, Karel Bezstarosti, Camila Gonzalo-Hansen, Haico van Attikum, Matty Verlaan-de Vries, Alfred C. O. Vertegaal, Jan H. J. Hoeijmakers, Jurgen A. Marteijn, Hannes Lans, Jeroen A. A. Demmers, Michiel Vermeulen, Titia K. Sixma, Tomoo Ogi, Wim Vermeulen, and Alex Pines. The small crl4csa ubiquitin ligase component dda1 regulates transcription-coupled repair dynamics. Nature Communications, Jul 2024. URL: https://doi.org/10.1038/s41467-024-50584-7, doi:10.1038/s41467-024-50584-7. This article has 17 citations and is from a highest quality peer-reviewed journal.

  9. (schiffmacher2024thesmallcrl4csa media ae42f398): Diana A. Llerena Schiffmacher, Shun-Hsiao Lee, Katarzyna W. Kliza, Arjan F. Theil, Masaki Akita, Angela Helfricht, Karel Bezstarosti, Camila Gonzalo-Hansen, Haico van Attikum, Matty Verlaan-de Vries, Alfred C. O. Vertegaal, Jan H. J. Hoeijmakers, Jurgen A. Marteijn, Hannes Lans, Jeroen A. A. Demmers, Michiel Vermeulen, Titia K. Sixma, Tomoo Ogi, Wim Vermeulen, and Alex Pines. The small crl4csa ubiquitin ligase component dda1 regulates transcription-coupled repair dynamics. Nature Communications, Jul 2024. URL: https://doi.org/10.1038/s41467-024-50584-7, doi:10.1038/s41467-024-50584-7. This article has 17 citations and is from a highest quality peer-reviewed journal.

  10. (schiffmacher2024thesmallcrl4csa media 9d6dd208): Diana A. Llerena Schiffmacher, Shun-Hsiao Lee, Katarzyna W. Kliza, Arjan F. Theil, Masaki Akita, Angela Helfricht, Karel Bezstarosti, Camila Gonzalo-Hansen, Haico van Attikum, Matty Verlaan-de Vries, Alfred C. O. Vertegaal, Jan H. J. Hoeijmakers, Jurgen A. Marteijn, Hannes Lans, Jeroen A. A. Demmers, Michiel Vermeulen, Titia K. Sixma, Tomoo Ogi, Wim Vermeulen, and Alex Pines. The small crl4csa ubiquitin ligase component dda1 regulates transcription-coupled repair dynamics. Nature Communications, Jul 2024. URL: https://doi.org/10.1038/s41467-024-50584-7, doi:10.1038/s41467-024-50584-7. This article has 17 citations and is from a highest quality peer-reviewed journal.

  11. (schiffmacher2024thesmallcrl4csa pages 14-15): Diana A. Llerena Schiffmacher, Shun-Hsiao Lee, Katarzyna W. Kliza, Arjan F. Theil, Masaki Akita, Angela Helfricht, Karel Bezstarosti, Camila Gonzalo-Hansen, Haico van Attikum, Matty Verlaan-de Vries, Alfred C. O. Vertegaal, Jan H. J. Hoeijmakers, Jurgen A. Marteijn, Hannes Lans, Jeroen A. A. Demmers, Michiel Vermeulen, Titia K. Sixma, Tomoo Ogi, Wim Vermeulen, and Alex Pines. The small crl4csa ubiquitin ligase component dda1 regulates transcription-coupled repair dynamics. Nature Communications, Jul 2024. URL: https://doi.org/10.1038/s41467-024-50584-7, doi:10.1038/s41467-024-50584-7. This article has 17 citations and is from a highest quality peer-reviewed journal.

  12. (yong2024developmentofpeptide pages 7-8): Darren Yong, Shabbir Ahmad, Mark F. Mabanglo, Levon Halabelian, Matthieu Schapira, Suzanne Ackloo, Sumera Perveen, Pegah Ghiabi, and Masoud Vedadi. Development of peptide displacement assays to screen for antagonists of ddb1 interactions. Biochemistry, 63:1297-1306, May 2024. URL: https://doi.org/10.1021/acs.biochem.4c00044, doi:10.1021/acs.biochem.4c00044. This article has 4 citations and is from a peer-reviewed journal.

  13. (yong2024developmentofpeptide pages 1-2): Darren Yong, Shabbir Ahmad, Mark F. Mabanglo, Levon Halabelian, Matthieu Schapira, Suzanne Ackloo, Sumera Perveen, Pegah Ghiabi, and Masoud Vedadi. Development of peptide displacement assays to screen for antagonists of ddb1 interactions. Biochemistry, 63:1297-1306, May 2024. URL: https://doi.org/10.1021/acs.biochem.4c00044, doi:10.1021/acs.biochem.4c00044. This article has 4 citations and is from a peer-reviewed journal.

  14. (jackson2024nativemassspectrometry pages 1-2): Cara Jackson and Rebecca Beveridge. Native mass spectrometry of complexes formed by molecular glues reveals stoichiometric rearrangement of e3 ligases. bioRxiv, Jun 2024. URL: https://doi.org/10.1101/2023.02.03.526954, doi:10.1101/2023.02.03.526954. This article has 15 citations.

  15. (OpenTargets Search: -DDA1): Open Targets Query (-DDA1, 5 results). Buniello, A. et al. (2025). Open Targets Platform: facilitating therapeutic hypotheses building in drug discovery. Nucleic Acids Research.

  16. (pines2023dda1anovel pages 1-5): Alex Pines, Diana Llerena Schiffmacher, Shun-Hsiao Lee, Katarzyna Kliza, Arjan Theil, Masaki Akita, Angela Helfricht, Karel Bezstarosti, Camila Gonzalo-Hansen, Haico van Attikum, Matty Verlaan-de Vries, Alfred Vertegaal, Jan Hoeijmakers, Jurgen Marteijn, Hannes Lans, Jeroen Demmers, Michiel Vermeulen, Titia Sixma, Tomoo Ogi, and Wim Vermeulen. Dda1, a novel factor in transcription-coupled repair, modulates crl4csa dynamics at dna damage-stalled rna polymerase ii. Research Square, Oct 2023. URL: https://doi.org/10.21203/rs.3.rs-3385435/v1, doi:10.21203/rs.3.rs-3385435/v1. This article has 4 citations.

Artifacts

Citations

  1. shabek2018structuralinsightsinto pages 3-4
  2. shabek2018structuralinsightsinto pages 1-3
  3. yong2024developmentofpeptide pages 7-8
  4. yong2024developmentofpeptide pages 1-2
  5. jackson2024nativemassspectrometry pages 1-2
  6. https://doi.org/10.1038/s41421-018-0064-8;
  7. https://doi.org/10.1128/mcb.02432-06
  8. https://doi.org/10.1128/mcb.02432-06;
  9. https://doi.org/10.21203/rs.3.rs-3385435/v1;
  10. https://doi.org/10.1038/s41467-024-50584-7;
  11. https://doi.org/10.1101/2023.02.03.526954
  12. https://doi.org/10.1038/s41467-024-50584-7
  13. https://doi.org/10.1101/2023.02.03.526954;
  14. https://doi.org/10.1021/acs.biochem.4c00044
  15. https://doi.org/10.1021/acs.biochem.4c00044;
  16. https://doi.org/10.1038/s41421-018-0064-8
  17. https://doi.org/10.21203/rs.3.rs-3385435/v1
  18. https://doi.org/10.1038/s41421-018-0064-8,
  19. https://doi.org/10.1128/mcb.02432-06,
  20. https://doi.org/10.1038/s41467-024-50584-7,
  21. https://doi.org/10.21203/rs.3.rs-3385435/v1,
  22. https://doi.org/10.1021/acs.biochem.4c00044,
  23. https://doi.org/10.1101/2023.02.03.526954,

πŸ“š Additional Documentation

Pn Notes

(DDA1-pn-notes.md)

DDA1 PN Consistency Notes

  • Generated: 2026-06-18
  • Project: PROTEOSTASIS
  • Scope: PN consistency rereview against local AIGR review and available deep-research artifacts
  • UniProt: Q9BW61
  • AIGR review status: COMPLETE
  • Review batch: proteostasis-batch-2026-06-13
  • Batch change status: added

Source Files Checked

Deep Research Files

AIGR Review Snapshot

  • Description: DDA1 (DET1- and DDB1-associated protein 1) is a small, evolutionarily conserved subunit shared by numerous CUL4-RING (CRL4) E3 ubiquitin ligase complexes. It is an integral, core component of DCX/CRL4 complexes built on a core of DDB1, cullin-4 (CUL4A or CUL4B) and RBX1, where it functions as a scaffolding subunit that wraps around DDB1 and the substrate receptor (DCAF) to stabilize the assembled ligase and promote efficient, processive substrate ubiquitination. DDA1 is not itself a substrate receptor and does not provide the catalytic RING; rather it acts as an accessory/stabilizing module that rigidifies the complex and positions the substrate for ubiquitin transfer. It engages DDB1 with high affinity (Kd in the low-nanomolar range) through a conserved extreme N-terminal segment (approximately the first 28 residues) that docks into a groove on the BPA beta-propeller of DDB1, anchoring DDA1 within the assembled ligase. It has been structurally and biochemically characterized as part of the DDB1-DCAF15-DDA1 ligase that mediates aryl-sulfonamide (indisulam/E7820)-induced neosubstrate degradation of the splicing factor RBM39 (and its paralog RBM23), and it is also part of the DDD core complex (DET1-DDA1-DDB1) that recruits UBE2E-family E2 enzymes. DDA1 is additionally an integral, structurally resolved component of the CRL4(CSA) ligase, where it modestly stabilizes the CSA-DDB1 module and helps coordinate the ubiquitination dynamics that drive transcription-coupled nucleotide excision repair at RNA polymerase II stalled on DNA lesions. Through its presence across many CRL4 complexes DDA1 broadly supports CUL4-dependent protein polyubiquitination and proteasomal degradation, with downstream consequences for diverse substrates and pathways. It localizes to the nucleus where most CRL4 complexes act.
  • Existing/core annotation action counts: ACCEPT: 14; KEEP_AS_NON_CORE: 8

PN Consistency Summary

  • Consistency: Consistent on biology β€” deep research, review and PN all describe DDA1 as a small shared CRL4 subunit that stabilizes the DDB1-DCAF assembly (not a receptor, not catalytic). Slight MF-vocabulary divergence: review assigns molecular_function GO:0005198 (structural molecule activity) with contributes_to GO:0061630, whereas PN maps the node to GO:0160072 (scaffold activity). No biological contradiction; both capture a non-catalytic structural/scaffolding role.
  • PN story / NEW pressure: PN projects GO:0160072 (scaffold) as new_to_goa β€” confirmed absent from DDA1 GOA (goa.tsv has no MF scaffold/adaptor term). GO:0160072 is real (OLS: brings together a ubiquitin ligase and a ligase-substrate adaptor). DDA1 stabilizes/positions the DCAF receptor and the ligase, so a scaffold-class MF is defensible, though GO:0160072's exact definition (bridging ligase + adaptor) is a tighter fit for DDB1 than for the small accessory DDA1. Verdict: defensible ADD, but borderline β€” DDA1 is better described as a stabilizing/structural subunit than as the bridging scaffold itself.
  • Evidence alignment: PN ref 17452440 = Pick et al. 2007 (DDD/DET1-DDA1-DDB1, UBE2E recruitment); the review cites this framework via PMID:16949367 and the falcon synthesis (Shabek 2018 structure, Schiffmacher 2024 CRL4(CSA)/TC-NER). Strong structural evidence (PMID:30564455, 31686031) underpins the stabilizing role. No conflict.
  • Verdict: Consistent; GO:0160072 (scaffold) is a defensible-but-borderline add vs the review's GO:0005198. Recommended edits: [YAML] optionally add GO:0160072 to DDA1 core MF (or reconcile GO:0005198 vs GO:0160072) to align the review with the PN scaffold projection.

Full Consistency Review

  • UniProt: Q9BW61 Β· batch: proteostasis-batch-2026-06-13 Β· review status: COMPLETE
  • PN placement: UPS|E3 ubiquitin and UBL ligases|Cul4A/Cul4B receptor scaffold ; PN-node mapping: group "Cul4A/Cul4B receptor scaffold"=mapped, ok_for_propagation, GO:0160072 (ubiquitin ligase complex scaffold activity); projected goa_status=new_to_goa.
  • Consistency: Consistent on biology β€” deep research, review and PN all describe DDA1 as a small shared CRL4 subunit that stabilizes the DDB1-DCAF assembly (not a receptor, not catalytic). Slight MF-vocabulary divergence: review assigns molecular_function GO:0005198 (structural molecule activity) with contributes_to GO:0061630, whereas PN maps the node to GO:0160072 (scaffold activity). No biological contradiction; both capture a non-catalytic structural/scaffolding role.
  • PN story / NEW pressure: PN projects GO:0160072 (scaffold) as new_to_goa β€” confirmed absent from DDA1 GOA (goa.tsv has no MF scaffold/adaptor term). GO:0160072 is real (OLS: brings together a ubiquitin ligase and a ligase-substrate adaptor). DDA1 stabilizes/positions the DCAF receptor and the ligase, so a scaffold-class MF is defensible, though GO:0160072's exact definition (bridging ligase + adaptor) is a tighter fit for DDB1 than for the small accessory DDA1. Verdict: defensible ADD, but borderline β€” DDA1 is better described as a stabilizing/structural subunit than as the bridging scaffold itself.
  • Mapping strategy: Node correctly distinguishes DDA1 ("receptor scaffold") from the substrate receptors (GO:1990756) and from catalysis β€” a good distinction. Status/scope appropriate. The review's GO:0005198 is arguably the more conservative MF; GO:0160072 leans into the scaffold framing.
  • Evidence alignment: PN ref 17452440 = Pick et al. 2007 (DDD/DET1-DDA1-DDB1, UBE2E recruitment); the review cites this framework via PMID:16949367 and the falcon synthesis (Shabek 2018 structure, Schiffmacher 2024 CRL4(CSA)/TC-NER). Strong structural evidence (PMID:30564455, 31686031) underpins the stabilizing role. No conflict.
  • Verdict: Consistent; GO:0160072 (scaffold) is a defensible-but-borderline add vs the review's GO:0005198. Recommended edits: [YAML] optionally add GO:0160072 to DDA1 core MF (or reconcile GO:0005198 vs GO:0160072) to align the review with the PN scaffold projection.

PN Dossier Context

  • review_batch: proteostasis-batch-2026-06-13
  • review_yaml: genes/human/DDA1/DDA1-ai-review.yaml
  • PN workbook rows: 1

PN row 1: Ubiquitin Proteasome System | E3 ubiquitin and UBL ligases | Cul4A/Cul4B receptor scaffold

  • UniProt: Q9BW61
  • In branches: UPS
  • Signature domains: (none)
  • Auxiliary domains: (none)
  • PN references (titles):
    • 17452440
  • PN-node mapping records (path + ancestors):
    • [group] Ubiquitin Proteasome System|E3 ubiquitin and UBL ligases|Cul4A/Cul4B receptor scaffold
      status=mapped scope=ok_for_propagation_to_go GO=[GO:0160072 ubiquitin ligase complex scaffold activity]
      rationale: This PN group captures cullin or cullin-associated scaffold roles in ubiquitin ligase complexes. The shared GO molecular-function target is ubiquitin ligase complex scaffold activity.
    • [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.

Projected GO annotations (1)

  • GO:0160072 ubiquitin ligase complex scaffold activity | scope=ok_for_propagation_to_go | goa_status=new_to_goa | from=Ubiquitin Proteasome System|E3 ubiquitin and UBL ligases|Cul4A/Cul4B receptor scaffold

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.

πŸ“„ View Raw YAML

id: Q9BW61
gene_symbol: DDA1
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: >-
  DDA1 (DET1- and DDB1-associated protein 1) is a small, evolutionarily conserved
  subunit shared by numerous CUL4-RING (CRL4) E3 ubiquitin ligase complexes. It is
  an integral, core component of DCX/CRL4 complexes built on a core of DDB1,
  cullin-4 (CUL4A or CUL4B) and RBX1, where it functions as a scaffolding subunit
  that wraps around DDB1 and the substrate receptor (DCAF) to stabilize the
  assembled ligase and promote efficient, processive substrate ubiquitination.
  DDA1 is not itself a substrate receptor and does not provide the catalytic RING;
  rather it acts as an accessory/stabilizing module that rigidifies the complex and
  positions the substrate for ubiquitin transfer. It engages DDB1 with high affinity
  (Kd in the low-nanomolar range) through a conserved extreme N-terminal segment
  (approximately the first 28 residues) that docks into a groove on the BPA
  beta-propeller of DDB1, anchoring DDA1 within the assembled ligase. It has been
  structurally and biochemically characterized as part of the DDB1-DCAF15-DDA1
  ligase that mediates aryl-sulfonamide (indisulam/E7820)-induced neosubstrate
  degradation of the splicing factor RBM39 (and its paralog RBM23), and it is also
  part of the DDD core complex (DET1-DDA1-DDB1) that recruits UBE2E-family E2
  enzymes. DDA1 is additionally an integral, structurally resolved component of the
  CRL4(CSA) ligase, where it modestly stabilizes the CSA-DDB1 module and helps
  coordinate the ubiquitination dynamics that drive transcription-coupled
  nucleotide excision repair at RNA polymerase II stalled on DNA lesions. Through
  its presence across many CRL4 complexes DDA1 broadly supports CUL4-dependent
  protein polyubiquitination and proteasomal degradation, with downstream
  consequences for diverse substrates and pathways. It localizes to the nucleus
  where most CRL4 complexes act.
existing_annotations:
- term:
    id: GO:0080008
    label: Cul4-RING E3 ubiquitin ligase complex
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: part_of
  review:
    summary: Phylogenetic assignment of DDA1 as part of a CUL4-RING E3 ubiquitin ligase complex, its core role as a shared stabilizing subunit.
    action: ACCEPT
    reason: Core complex membership; DDA1 is an integral component of numerous DCX/CRL4 ligases; supported experimentally and conserved.
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes
- term:
    id: GO:0032434
    label: regulation of proteasomal ubiquitin-dependent protein catabolic process
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: involved_in
  review:
    summary: InterPro-based assignment of involvement in regulating proteasomal ubiquitin-dependent protein catabolism, consistent with DDA1 enhancing CRL4-mediated substrate degradation.
    action: ACCEPT
    reason: Correct; as a stabilizing subunit DDA1 promotes efficient CRL4-mediated ubiquitination and subsequent proteasomal degradation of substrates.
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: which mediate the ubiquitination and subsequent proteasomal degradation of target proteins
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:20562859
  qualifier: enables
  review:
    summary: Interaction with DDB1 (Q16531) from an autophagy-system interactome study. Bare protein binding is uninformative.
    action: KEEP_AS_NON_CORE
    reason: Real DDB1 interaction (core complex partner) but bare protein binding is uninformative; captured by complex membership.
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: which consist of a core of DDB1, cullin-4 (CUL4A or CUL4B), DDA1 and RBX1
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:25416956
  qualifier: enables
  review:
    summary: Interactions (Q6RW13, Q96DZ9/DCAF15) from a proteome-scale interactome study. Bare protein binding is uninformative.
    action: KEEP_AS_NON_CORE
    reason: High-throughput interactions including DCAF15 (a CRL4 substrate receptor DDA1 stabilizes), but bare protein binding is uninformative.
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: Component of the DCX(DCAF15) complex, also named CLR4(DCAF15) complex, composed of DCAF15, DDB1, cullin-4 (CUL4A or CUL4B), DDA1 and RBX1
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:30564455
  qualifier: enables
  review:
    summary: Interaction with DDB1 (Q16531) from the structural study of DDA1 as a core component of CRL4-DDB1. The DDB1 contact is mediated by a conserved N-terminal segment binding the DDB1 BPA propeller with low-nanomolar affinity. Bare protein binding is uninformative.
    action: KEEP_AS_NON_CORE
    reason: Real, functionally central DDB1 interaction underpinning DDA1's scaffolding role, but bare protein binding is uninformative; captured by complex membership. The specific structural mechanism (N-terminal anchor on the DDB1 BPA propeller) is recorded in the falcon findings.
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: acts as a scaffolding subunit required to stabilize the complex
    - reference_id: file:human/DDA1/DDA1-deep-research-falcon.md
      supporting_text: Shabek et al. mapped DDB1 binding to a conserved **N-terminal 28-aa segment** (DDA1-NT), solved the **DDB1–DDA1-NT crystal structure at ~3.1 Γ…**, and localized binding to a groove on the **BPA propeller** of DDB1
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  qualifier: enables
  review:
    summary: Interactions (Q8IZV5, Q96DZ9-2/DCAF15 isoform, Q96KN3) from a binary interactome reference map. Bare protein binding is uninformative.
    action: KEEP_AS_NON_CORE
    reason: High-throughput interactome; bare protein binding is uninformative.
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32814053
  qualifier: enables
  review:
    summary: Interaction (O60260-5, PARK2/parkin isoform) from a neurodegeneration interactome study. Bare protein binding is uninformative.
    action: KEEP_AS_NON_CORE
    reason: High-throughput interactome; bare protein binding is uninformative and not a core function.
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:35271311
  qualifier: enables
  review:
    summary: Interaction with DDB1 (Q16531) from the OpenCell endogenous-tagging interactome. Bare protein binding is uninformative.
    action: KEEP_AS_NON_CORE
    reason: Real DDB1 interaction but bare protein binding is uninformative; captured by complex membership.
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: which consist of a core of DDB1, cullin-4 (CUL4A or CUL4B), DDA1 and RBX1
- term:
    id: GO:0016567
    label: protein ubiquitination
  evidence_type: IEA
  original_reference_id: GO_REF:0000041
  qualifier: involved_in
  review:
    summary: UniPathway-derived general protein-ubiquitination process, consistent with DDA1's role in CRL4-mediated ubiquitination.
    action: ACCEPT
    reason: Correct; DDA1 contributes to CRL4-mediated protein ubiquitination as a stabilizing subunit.
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: 'PATHWAY: Protein modification; protein ubiquitination.'
- term:
    id: GO:0031464
    label: Cul4A-RING E3 ubiquitin ligase complex
  evidence_type: IPI
  original_reference_id: PMID:31693891
  qualifier: part_of
  review:
    summary: Physical-interaction (ComplexPortal) evidence that DDA1 is part of the CUL4A-RING (CRL4A-DCAF15) ligase complex. Core complex membership.
    action: ACCEPT
    reason: Core complex membership with experimental support; DDA1 is part of CRL4(DCAF15).
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: composed of DCAF15, DDB1, cullin-4 (CUL4A or CUL4B), DDA1 and RBX1
- term:
    id: GO:0031465
    label: Cul4B-RING E3 ubiquitin ligase complex
  evidence_type: NAS
  original_reference_id: PMID:31452512
  qualifier: part_of
  review:
    summary: Author statement (ComplexPortal) that DDA1 is part of the CUL4B-RING (CRL4B-DCAF15) ligase complex. Core complex membership.
    action: ACCEPT
    reason: Core complex membership; DDA1 is a shared subunit of CUL4A- and CUL4B-based CRL4(DCAF15) ligases.
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: composed of DCAF15, DDB1, cullin-4 (CUL4A or CUL4B), DDA1 and RBX1
- term:
    id: GO:0032814
    label: regulation of natural killer cell activation
  evidence_type: NAS
  original_reference_id: PMID:31452512
  qualifier: involved_in
  review:
    summary: Author statement linking the CRL4-DCAF15 ligase (of which DDA1 is the stabilizing subunit) to regulation of NK-cell-mediated immune surveillance; DCAF15 disruption sensitizes cancer cells to NK clearance.
    action: KEEP_AS_NON_CORE
    reason: A real but indirect, context-specific role mediated through the DCAF15 substrate receptor; peripheral to DDA1's core CRL4-stabilizing function.
    supported_by:
    - reference_id: PMID:31452512
      supporting_text: the ubiquitin ligase substrate adaptor DCAF15 strongly sensitized cancer cells to NK-mediated clearance
- term:
    id: GO:0000209
    label: protein polyubiquitination
  evidence_type: IMP
  original_reference_id: PMID:31686031
  qualifier: involved_in
  review:
    summary: Mutant-phenotype evidence that DDA1, within the DDB1-DCAF15-DDA1 core ligase, supports polyubiquitination (E7820-mediated RBM39 degradation). Core process role.
    action: ACCEPT
    reason: Supported; the DDB1-DCAF15-DDA1 ligase polyubiquitinates RBM39, with DDA1 stabilizing the DCAF15 fold.
    supported_by:
    - reference_id: PMID:31686031
      supporting_text: We show that DCAF15 adopts a new fold stabilized by DDA1
- term:
    id: GO:0080008
    label: Cul4-RING E3 ubiquitin ligase complex
  evidence_type: IDA
  original_reference_id: PMID:28302793
  qualifier: part_of
  review:
    summary: Direct evidence that DDA1 is part of a CUL4-RING (CRL4-DCAF15) E3 ligase complex mediating RBM39 degradation. Core complex membership.
    action: ACCEPT
    reason: Core complex membership with direct support.
    supported_by:
    - reference_id: PMID:28302793
      supporting_text: indisulam promotes the recruitment of RBM39 (RNA binding motif protein 39) to the CUL4-DCAF15 E3 ubiquitin ligase
- term:
    id: GO:0080008
    label: Cul4-RING E3 ubiquitin ligase complex
  evidence_type: IDA
  original_reference_id: PMID:31686031
  qualifier: part_of
  review:
    summary: Direct (cryo-EM) evidence that DDA1 is part of the DDB1-DCAF15-DDA1 core CRL4 ligase complex. Core complex membership.
    action: ACCEPT
    reason: Core complex membership with direct structural support.
    supported_by:
    - reference_id: PMID:31686031
      supporting_text: the cryo-EM structure of the DDB1-DCAF15-DDA1 core ligase complex bound to RBM39
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:16949367
  qualifier: enables
  review:
    summary: Interactions with DDB1, CUL4A and CUL4B from the DCAF-family study; establishes DDA1 association with the CUL4-DDB1 core. Bare protein binding is uninformative.
    action: KEEP_AS_NON_CORE
    reason: Real core-complex interactions but bare protein binding is uninformative; captured by complex membership.
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: which consist of a core of DDB1, cullin-4 (CUL4A or CUL4B), DDA1 and RBX1
- term:
    id: GO:0080008
    label: Cul4-RING E3 ubiquitin ligase complex
  evidence_type: IDA
  original_reference_id: PMID:16949367
  qualifier: part_of
  review:
    summary: Direct evidence (DCAF-family study) that DDA1 is part of a CUL4-RING E3 ligase complex. Core complex membership.
    action: ACCEPT
    reason: Core complex membership with direct support.
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-8952638
  qualifier: located_in
  review:
    summary: Reactome curation of DDA1 nucleoplasmic localization within a CRL4 neddylation reaction. Consistent with the nuclear site of CRL4 action.
    action: ACCEPT
    reason: Correct localization; CRL4 complexes containing DDA1 act in the nucleus.
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-8952639
  qualifier: located_in
  review:
    summary: Reactome curation of DDA1 nucleoplasmic localization within a CRL4 neddylation reaction.
    action: ACCEPT
    reason: Correct localization; redundant with the other nucleoplasm annotations.
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-8955245
  qualifier: located_in
  review:
    summary: Reactome curation of DDA1 nucleoplasmic localization within a CRL4 regulation reaction (CAND1 binds CRL4).
    action: ACCEPT
    reason: Correct localization; redundant with the other nucleoplasm annotations.
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-8955285
  qualifier: located_in
  review:
    summary: Reactome curation of DDA1 nucleoplasmic localization within a CRL4 regulation reaction (COMMDs displace CAND1).
    action: ACCEPT
    reason: Correct localization; redundant with the other nucleoplasm annotations.
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-8956045
  qualifier: located_in
  review:
    summary: Reactome curation of DDA1 nucleoplasmic localization within a CRL4 regulation reaction (COP9 signalosome deneddylates CRL4).
    action: ACCEPT
    reason: Correct localization; redundant with the other nucleoplasm annotations.
    supported_by:
    - reference_id: file:human/DDA1/DDA1-uniprot.txt
      supporting_text: Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes
references:
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO
    terms
  findings: []
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000041
  title: Gene Ontology annotation based on UniPathway vocabulary mapping
  findings: []
- id: PMID:16949367
  title: A family of diverse Cul4-Ddb1-interacting proteins includes Cdt2, which is
    required for S phase destruction of the replication factor Cdt1.
  findings:
  - statement: Defines the family of DDB1- and CUL4-associated factors (DCAFs); DDA1 associates with the CUL4-DDB1 core.
    reference_section_type: ABSTRACT
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: Establishes the DCAF/CUL4-DDB1 framework within which DDA1 acts; source of complex-membership and DDB1/CUL4 interaction annotations.
- id: PMID:20562859
  title: Network organization of the human autophagy system.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: Autophagy-system interactome; source of a DDB1 interaction annotation.
- id: PMID:25416956
  title: A proteome-scale map of the human interactome network.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: Proteome-scale interactome; source of high-throughput protein binding annotations (incl. DCAF15).
- id: PMID:28302793
  title: Anticancer sulfonamides target splicing by inducing RBM39 degradation via
    recruitment to DCAF15.
  findings:
  - statement: Indisulam recruits RBM39 to the CUL4-DCAF15 E3 ligase (containing DDA1) for polyubiquitination and proteasomal degradation.
    reference_section_type: ABSTRACT
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Establishes the CRL4-DCAF15 (with DDA1) sulfonamide-induced RBM39 degradation; source of complex-membership annotation.
- id: PMID:30564455
  title: Structural insights into DDA1 function as a core component of the CRL4-DDB1
    ubiquitin ligase.
  findings:
  - statement: Structural characterization of DDA1 as a core scaffolding/stabilizing component of the CRL4-DDB1 ubiquitin ligase.
    reference_section_type: TITLE
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Full text available; the principal structural study defining DDA1's core scaffolding role in CRL4-DDB1; source of a DDB1 interaction annotation.
- id: PMID:31452512
  title: Systematic identification of cancer cell vulnerabilities to natural killer
    cell-mediated immune surveillance.
  findings:
  - statement: DCAF15 (the substrate receptor of a CRL4 complex containing DDA1) disruption sensitizes cancer cells to NK-mediated clearance; cohesin members are endogenous DCAF15 substrates.
    reference_section_type: ABSTRACT
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: Full text available; source of CUL4B-RING complex membership (NAS) and the peripheral NK-cell-regulation (NAS) annotations, both mediated via DCAF15.
- id: PMID:31686031
  title: Structural complementarity facilitates E7820-mediated degradation of RBM39
    by DCAF15.
  findings:
  - statement: Cryo-EM structure of the DDB1-DCAF15-DDA1 core ligase bound to RBM39; DCAF15 adopts a new fold stabilized by DDA1.
    reference_section_type: ABSTRACT
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Full text available; directly demonstrates DDA1 stabilizing the DCAF15 fold within the CRL4 core; source of polyubiquitination (IMP) and complex-membership (IDA) annotations.
- id: PMID:31693891
  title: Aryl Sulfonamides Degrade RBM39 and RBM23 by Recruitment to CRL4-DCAF15.
  findings:
  - statement: Aryl sulfonamides recruit RBM39 and its paralog RBM23 to the CRL4-DCAF15 ligase (containing DDA1) for ubiquitination and degradation.
    reference_section_type: ABSTRACT
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Full text available; source of CUL4A-RING complex membership (IPI/ComplexPortal) annotation.
- id: PMID:32296183
  title: A reference map of the human binary protein interactome.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: Binary interactome reference map; source of high-throughput protein binding annotations (incl. DCAF15 isoform).
- id: PMID:32814053
  title: Interactome Mapping Provides a Network of Neurodegenerative Disease Proteins
    and Uncovers Widespread Protein Aggregation in Affected Brains.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: Neurodegeneration interactome; source of a high-throughput protein binding annotation.
- id: PMID:35271311
  title: 'OpenCell: Endogenous tagging for the cartography of human cellular organization.'
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: Full text available; OpenCell endogenous-tagging interactome; source of a DDB1 interaction annotation.
- id: file:human/DDA1/DDA1-deep-research-falcon.md
  title: Falcon deep research report for human DDA1
  findings:
  - statement: DDA1 binds DDB1 with high affinity through a conserved extreme N-terminal segment (~first 28 residues) that docks into a groove on the BPA beta-propeller of DDB1, defining its anchoring mechanism within CRL4 ligases.
    supporting_text: Shabek et al. mapped DDB1 binding to a conserved **N-terminal 28-aa segment** (DDA1-NT), solved the **DDB1–DDA1-NT crystal structure at ~3.1 Γ…**, and localized binding to a groove on the **BPA propeller** of DDB1
  - statement: DDA1 is best supported as a small structural/regulatory subunit of DDB1-CUL4 ligases rather than an enzyme, modulating ligase architecture and ubiquitination output in a context-dependent manner.
    supporting_text: 'DDA1 is not an enzyme** (no independent catalytic reaction is described). Instead, it is best supported as a **small structural/regulatory subunit** of certain DDB1–CUL4 E3 ligase assemblies that can modulate ligase architecture and ubiquitination output in a **context-dependent** manner'
  - statement: DDA1 is an integral component of CRL4(CSA) that coordinates ubiquitination dynamics during transcription-coupled nucleotide excision repair (TC-NER) and is required for efficient repair turnover/progression.
    supporting_text: DDA1 was identified as a **CSA interactor** by single-step complex isolation/MS and shown by cryo-EM to be an **integral CRL4CSA component**; functionally, DDA1 was concluded to **coordinate ubiquitination dynamics during TC-NER** and be **required for efficient turnover/progression** of the repair process
  - statement: DDA1 provides a modest but reproducible thermal stabilization of the CSA-DDB1 module, with stabilization driven mainly by DDA1-DDB1 contacts.
    supporting_text: DDA1 provided a modest, reproducible **~1 Β°C** thermal stabilization of CSA–DDB1 measured by nanoDSF, and truncation removing a CSA-interacting helix had a similar stabilization, implying stabilization is driven mainly by **DDA1–DDB1** contacts
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Falcon synthesis (Shabek 2018 Cell Discovery, Pick 2007 MCB, Schiffmacher 2024 Nat Commun, Pines 2023) of DDA1 as a small DDB1-anchored CRL4 stabilizing subunit and a TC-NER CRL4(CSA) component; the N-terminal DDB1-binding mechanism and the new CRL4(CSA)/TC-NER role are consistent with the UniProt record and existing structural annotations. Citations are author-year/DOI rather than PMIDs.
- id: Reactome:R-HSA-8952638
  title: AcM-UBE2M transfers NEDD8 to CRL4 E3 ubiquitin ligase complex
  findings: []
- id: Reactome:R-HSA-8952639
  title: NEDD8:AcM-UBE2M binds CRL4 E3 ubiquitin ligase complex
  findings: []
- id: Reactome:R-HSA-8955245
  title: CAND1 binds CRL4 E3 ubiquitin ligase in the nucleus
  findings: []
- id: Reactome:R-HSA-8955285
  title: COMMDs displace CAND1 from CRL4 E3 ubiquitin ligase complex
  findings: []
- id: Reactome:R-HSA-8956045
  title: COP9 signalosome deneddylates nuclear CRL4 E3 ubiquitin ligase complex
  findings: []
core_functions:
- description: Shared core scaffolding/stabilizing subunit of CUL4-RING (CRL4/DCX) E3 ubiquitin ligase complexes (DDB1-CUL4A/CUL4B-RBX1 with a DCAF receptor), where DDA1 rigidifies the assembly and the substrate receptor fold to promote efficient CRL4-mediated polyubiquitination and proteasomal degradation of substrates. DDA1 is neither the substrate receptor nor the catalytic RING.
  molecular_function:
    id: GO:0005198
    label: structural molecule activity
  contributes_to_molecular_function:
    id: GO:0061630
    label: ubiquitin protein ligase activity
  locations:
  - id: GO:0005654
    label: nucleoplasm
  supported_by:
  - reference_id: file:human/DDA1/DDA1-uniprot.txt
    supporting_text: acts as a scaffolding subunit required to stabilize the complex
  - reference_id: PMID:31686031
    supporting_text: We show that DCAF15 adopts a new fold stabilized by DDA1
  - reference_id: file:human/DDA1/DDA1-deep-research-falcon.md
    supporting_text: Shabek et al. mapped DDB1 binding to a conserved **N-terminal 28-aa segment** (DDA1-NT), solved the **DDB1–DDA1-NT crystal structure at ~3.1 Γ…**, and localized binding to a groove on the **BPA propeller** of DDB1
  in_complex:
    id: GO:0080008
    label: Cul4-RING E3 ubiquitin ligase complex
  directly_involved_in:
  - id: GO:0000209
    label: protein polyubiquitination
- description: As an integral component of the CRL4(CSA) ligase, DDA1 coordinates the ubiquitination dynamics that drive transcription-coupled nucleotide excision repair at RNA polymerase II stalled on DNA lesions, modestly stabilizing the CSA-DDB1 module and supporting efficient repair turnover/progression.
  molecular_function:
    id: GO:0005198
    label: structural molecule activity
  contributes_to_molecular_function:
    id: GO:0061630
    label: ubiquitin protein ligase activity
  locations:
  - id: GO:0005654
    label: nucleoplasm
  supported_by:
  - reference_id: file:human/DDA1/DDA1-deep-research-falcon.md
    supporting_text: DDA1 was identified as a **CSA interactor** by single-step complex isolation/MS and shown by cryo-EM to be an **integral CRL4CSA component**; functionally, DDA1 was concluded to **coordinate ubiquitination dynamics during TC-NER** and be **required for efficient turnover/progression** of the repair process
  in_complex:
    id: GO:0080008
    label: Cul4-RING E3 ubiquitin ligase complex
  directly_involved_in:
  - id: GO:0006283
    label: transcription-coupled nucleotide-excision repair
proposed_new_terms: []
suggested_questions:
- question: Across the full repertoire of CRL4 complexes, which substrate receptors (DCAFs) depend most strongly on DDA1 for assembly/activity, and is DDA1 dispensable for some?
- question: Does DDA1 contribute only to complex stability and substrate positioning, or does it also influence ubiquitin-chain processivity, linkage type, or neddylation/deneddylation dynamics of CRL4 ligases?
- question: In CRL4(CSA)-dependent transcription-coupled repair, does DDA1 act primarily by stabilizing the CSA-DDB1 module, by tuning the residence time/ubiquitination progression on lesion-stalled RNA polymerase II, or both, and which TC-NER substrates (e.g., CSB, UVSSA, RNAPII) depend on DDA1 for timely turnover?
suggested_experiments:
- description: Compare RBM39 (and endogenous substrate) ubiquitination kinetics in reconstituted DDB1-CUL4-RBX1-DCAF complexes with and without DDA1, measuring effects on substrate affinity, ubiquitin-transfer rate, and processivity.
- description: Perform quantitative proteomics of DDA1-knockout versus wild-type cells to define which CRL4 substrate pools are stabilized, distinguishing DDA1-dependent from DDA1-independent CRL4 functions.
- description: In DDA1-depleted cells, measure TC-NER kinetics (e.g., recovery of RNA synthesis after UV, RNAPII clearance from lesions, and ubiquitination of CSB/UVSSA) to test whether DDA1 is required for efficient CRL4(CSA)-driven repair progression, and reconstitute CRL4(CSA) in vitro +/- DDA1 to dissect its effect on ubiquitination dynamics.