Affinage

UBXN1

UBX domain-containing protein 1 · UniProt Q04323

Length
297 aa
Mass
33.3 kDa
Annotated
2026-06-10
23 papers in source corpus 16 papers cited in narrative 16 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

UBXN1 is a UBA-UBX domain protein that functions both as a VCP/p97 cofactor and as a linkage-selective ubiquitin reader controlling protein quality control and innate immune signaling (PMID:21135095, PMID:20351172). Its extended UBA domain confers specificity for K6-linked polyubiquitin, collapsing the two solution conformations of K6 diubiquitin into a single bound conformation (PMID:32039147); through this activity UBXN1 recognizes autoubiquitinated BRCA1 and, via additional ubiquitin-independent contacts to the BRCA1/BARD1 heterodimer, sharply represses its E3 ligase activity (PMID:20351172). As a p97 adaptor it requires both polyubiquitin binding (UBA) and p97 binding (UBX), and couples ubiquitin recognition to triage of clients: it negatively modulates ERAD by protecting polyubiquitin chains from deubiquitinases and delaying substrate degradation (PMID:21135095, PMID:27785701), directs the VCP-dependent disposal of ubiquitylated BAG6 clients prior to ER insertion (PMID:29685906), is required for aggresome formation and clearance of polyQ inclusions (PMID:33712450), and translocates with VCP to depolarized mitochondria during PRKN-dependent mitophagy to facilitate MFN2 removal (PMID:33966597). Independently of p97, UBXN1 represses translation to restrain the unfolded protein response and maintain ER proteostasis (PMID:38177917). UBXN1 also acts as a negative regulator of inflammatory and antiviral signaling: it blocks cIAP1 recruitment to TNFR1 to limit RIP1 polyubiquitination and NF-κB activation (PMID:25681446), and binds MAVS to disrupt the MAVS/TRAF3/TRAF6 signalosome and dampen RNA-virus-induced interferon responses (PMID:23545497). Consistent with its role as a signaling brake, UBXN1 abundance is suppressed at multiple levels—METTL3/YTHDF2-dependent m6A mRNA decay (PMID:34246306), PRC2-mediated H3K27 trimethylation at its promoter (PMID:33754075), and UBR5-mediated Lys11-linked ubiquitination and degradation (PMID:38240906)—each releasing NF-κB activity.

Mechanistic history

Synthesis pass · year-by-year structured walk · 13 steps
  1. 2010 High

    Established UBXN1 as a linkage-selective ubiquitin reader that suppresses an E3 ligase, defining a non-degradative function for its UBA domain.

    Evidence Biochemical pulldown, in vitro ubiquitination, and domain mapping showing UBA binding to K6-polyUb on BRCA1 plus ubiquitin-independent BRCA1/BARD1 contacts that reduce ligase activity

    PMID:20351172

    Open questions at the time
    • Cellular consequences for BRCA1-dependent DNA repair not established
    • Stoichiometry of inhibition unresolved
  2. 2010 High

    Defined UBXN1 as a bona fide p97 adaptor whose ubiquitin and p97 binding cooperate, and showed it negatively tunes ERAD by shielding chains from deubiquitination.

    Evidence In vitro p97 binding assays, ERAD substrate degradation assays, and deubiquitinase (ataxin-3) protection assays

    PMID:21135095

    Open questions at the time
    • Which ERAD substrates are physiologically affected not defined
    • Mechanism of chain protection structurally unresolved
  3. 2013 High

    Showed UBXN1 acts as a virus-induced brake on RLR/MAVS antiviral signaling, distinguishing RNA-virus-specific suppression from TLR/DNA-virus pathways.

    Evidence Reciprocal Co-IP, siRNA/overexpression, and IFN reporter assays across multiple RNA viruses

    PMID:23545497

    Open questions at the time
    • Whether ubiquitin-binding or p97 is required for MAVS regulation not addressed
    • In vivo antiviral relevance untested
  4. 2015 High

    Identified a p97-independent role for UBXN1 in restraining NF-κB by competitively blocking cIAP1 recruitment to TNFR1.

    Evidence siRNA screen, competitive Co-IP, RIP1 ubiquitination and NF-κB reporter assays, with VCP knockdown ruling out p97 dependence

    PMID:25681446

    Open questions at the time
    • Structural basis of cIAP1 competition unknown
    • Whether ubiquitin binding contributes not resolved
  5. 2016 Medium

    Distinguished UBXN1 from other UBA-UBX proteins functionally, showing it selectively delays ERAD substrate degradation and is stress-regulated.

    Evidence ERAD substrate degradation assays with multiple substrates and siRNA knockdown comparing p47 and SAKS1

    PMID:27785701

    Open questions at the time
    • Single method per substrate
    • Mechanistic basis for substrate selectivity not defined
  6. 2018 High

    Placed UBXN1 in the BAG6 triage pathway as the VCP adaptor handling ubiquitylated cytosolic clients before ER insertion, distinct from ERAD.

    Evidence Reciprocal Co-IP, KO cell lines, degradation assays, and solubility fractionation with proteotoxic stress assays

    PMID:29685906

    Open questions at the time
    • Client repertoire incompletely mapped
    • How triage versus ERAD is discriminated unknown
  7. 2020 High

    Provided the structural basis for K6-linkage selectivity, showing a C-terminally extended UBA domain enforces specificity.

    Evidence NMR with 15N-labeled synthetic diubiquitins comparing extended versus non-extended UBA constructs

    PMID:32039147

    Open questions at the time
    • Full-length protein conformation not solved
    • Cellular K6-chain ligands beyond BRCA1 not catalogued
  8. 2021 High

    Extended UBXN1's quality-control role to organelle clearance, defining it as a VCP cofactor for aggresome formation and for PRKN-dependent mitophagy.

    Evidence KO cell lines, imaging, C. elegans HD model, mitochondrial fractionation, UBX-domain-dependent PRKN Co-IP, and mitophagy flux assays

    PMID:33712450 PMID:33966597

    Open questions at the time
    • Direct ubiquitin substrates at aggresomes/mitochondria not all defined
    • Relationship between aggresome and mitophagy functions unclear
  9. 2021 Medium

    Revealed UBXN1 is a transcriptionally and post-transcriptionally suppressed NF-κB brake, via m6A-driven mRNA decay and PRC2-mediated promoter silencing.

    Evidence MeRIP/RIP and RNA stability assays (METTL3/YTHDF2); ChIRP/ChIP at the UBXN1 promoter (PRADX/PRC2/DDX5); NF-κB reporters and xenografts

    PMID:33754075 PMID:34246306

    Open questions at the time
    • Direct effect on NF-κB independent of confounding pathways not fully isolated
    • Tissue specificity of regulation unclear
  10. 2024 Medium

    Identified UBR5 as an E3 that degrades UBXN1 via Lys11-linked ubiquitination downstream of SUB1, closing a regulatory loop releasing NF-κB.

    Evidence Co-IP, Lys11-linkage ubiquitination assays, knockdown, NF-κB reporters, and in vivo tumor models

    PMID:38240906

    Open questions at the time
    • UBR5 degron on UBXN1 not mapped
    • Single-lab finding
  11. 2024 High

    Defined a p97-independent role for UBXN1 in repressing translation to restrain the UPR and maintain ER proteostasis.

    Evidence KO cells with quantitative proteomics, UPR reporters, translation assays, and p97-inhibition epistasis

    PMID:38177917

    Open questions at the time
    • Molecular mechanism of translational repression unknown
    • Direct effectors of translation control unidentified
  12. 2024 Medium

    Implicated UBXN1 as a positive regulator of noncanonical inflammasome activation through caspase-4/11 binding with unanchored polyubiquitin.

    Evidence Co-IP, KO cells and mice, inflammasome/pyroptosis assays, and USP5-based depletion of unanchored polyUb (preprint)

    PMID:bio_10.1101_2024.10.30.621131

    Open questions at the time
    • Preprint not yet peer-reviewed
    • How a negative NF-κB regulator positively drives inflammasomes mechanistically unresolved
  13. 2024 Medium

    Linked UBXN1 to mitochondrial homeostasis through interaction with prohibitin and support of HCC cell survival.

    Evidence Co-IP, KO/knockdown, apoptosis assays, and Sleeping Beauty mouse liver tumor models

    PMID:38773518

    Open questions at the time
    • Single binding method
    • Mechanism by which UBXN1 sustains PHB expression unknown

Open questions

Synthesis pass · forward-looking unresolved questions
  • How UBXN1 integrates its dual identity—p97-coupled quality-control adaptor versus p97-independent signaling/translation regulator—into a coherent regulatory logic remains unresolved.
  • No unified model linking ubiquitin-linkage selectivity to specific cellular outputs
  • Determinants of when UBXN1 engages p97 versus acts independently unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098772 molecular function regulator activity 4 GO:0060090 molecular adaptor activity 3 GO:0140096 catalytic activity, acting on a protein 2 GO:0045182 translation regulator activity 1
Localization
GO:0005783 endoplasmic reticulum 3 GO:0005739 mitochondrion 2 GO:0005829 cytosol 2
Pathway
R-HSA-392499 Metabolism of proteins 3 R-HSA-162582 Signal Transduction 2 R-HSA-168256 Immune System 2 R-HSA-9612973 Autophagy 2
Complex memberships
BAG6 complexVCP/p97-UBXN1 complex

Evidence

Reading pass · 16 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2013 UBXN1 inhibits RLR/MAVS-mediated antiviral signaling by binding to MAVS, interfering with MAVS oligomerization, and disrupting the MAVS/TRAF3/TRAF6 signalosome; UBXN1 is induced following viral infection and acts specifically on RNA-virus-induced (not TLR3, TLR4, or DNA-virus-induced) innate immune responses. Co-immunoprecipitation, siRNA knockdown, overexpression in cell lines, viral infection assays (VSV, Sendai, WNV, dengue); reporter assays for IFN induction Cell reports High 23545497
2010 UBXN1 recognizes autoubiquitinated BRCA1 through a bipartite interaction: the UBA domain binds K6-linked polyubiquitin chains on BRCA1, while C-terminal sequences bind the BRCA1/BARD1 heterodimer in a ubiquitin-independent manner; UBXN1 binding dramatically reduces the E3 ligase activity of BRCA1/BARD1. Biochemical pulldown, Co-immunoprecipitation, in vitro ubiquitination assays, domain-mapping experiments with UBA and C-terminal UBXN1 fragments Molecular and cellular biology High 20351172
2015 UBXN1 is a negative regulator of TNFα-triggered NF-κB signaling: it interacts with cIAP1 (an E3 ligase for RIP1 in the TNFR1 complex), competitively blocks cIAP1 recruitment to TNFR1, and thereby inhibits RIP1 polyubiquitination; this mechanism is independent of VCP/p97 (p97 knockdown does not affect UBXN1-mediated NF-κB inhibition). siRNA screen (51 ubiquitin-associated domain proteins), Co-immunoprecipitation, overexpression/knockdown, NF-κB reporter assays, RIP1 ubiquitination assays The Journal of biological chemistry High 25681446
2010 UBXN1 (SAKS1) acts as a p97 adaptor that negatively modulates ERAD: it requires both polyubiquitin binding (UBA domain) and p97 binding (UBX domain) to function, and polyubiquitin binding positively regulates the SAKS1–p97 association; SAKS1 also protects polyubiquitin chains from deubiquitinase activity (e.g., ataxin-3), thereby slowing ERAD substrate degradation. In vitro binding assays, ERAD substrate degradation assays, p97 interaction studies, deubiquitinase protection assays The Journal of biological chemistry High 21135095
2018 UBXN1 serves as the VCP adaptor in the BAG6 triage pathway: the VCP–UBXN1 complex recognizes ubiquitylated cytosolic proteins bound to the BAG6 complex prior to ER insertion (but not during ERAD); loss of VCP–UBXN1 causes inappropriate stabilization of ubiquitylated BAG6 clients and their accumulation in insoluble aggregates, sensitizing cells to proteotoxic stress. Co-immunoprecipitation, siRNA/KO cell lines, proteasomal degradation assays, protein aggregation/solubility fractionation, proteotoxic stress assays Molecular and cellular biology High 29685906
2021 UBXN1 (SAKS1) is a VCP/p97 cofactor required for mitophagy initiation: upon mitochondrial depolarization and in a PRKN-dependent manner, UBXN1 translocates with VCP to mitochondria; UBXN1 physically interacts with PRKN via its UBX domain; loss of UBXN1 impairs VCP and PRKN recruitment to depolarized mitochondria, reduces mitophagic flux, and leads to accumulation of MFN2 in para-mitochondrial 'blobs', indicating UBXN1 facilitates MFN2 removal from the outer mitochondrial membrane downstream of PINK1. Live-cell imaging, mitochondrial fractionation, Co-immunoprecipitation (UBX-domain-dependent PRKN interaction), siRNA/KO cell lines, mitophagy flux assays, domain-mapping (UBX deletion) Autophagy High 33966597
2021 UBXN1 is required for aggresome formation: UBXN1 is recruited to aggresomes upon proteasome inhibition; UBXN1-knockout cells cannot form aggresomes and show increased Huntingtin polyQ inclusion bodies in mammalian cells and in a C. elegans Huntington's disease model; the p97–UBXN1 complex mediates aggresome formation and clearance. KO cell lines, immunofluorescence/live imaging of aggresome formation, C. elegans genetic model, siRNA, proteasome inhibition assays Journal of cell science High 33712450
2024 UBXN1 is a negative regulator of the unfolded protein response (UPR) and ER proteostasis: loss of UBXN1 activates the UPR, upregulates ER quality-control proteins, and increases translation in both resting and ER-stressed cells; this translational repression function is independent of p97. KO cell lines, quantitative proteomics, UPR reporter assays, translation assays, epistasis with p97 inhibition EMBO reports High 38177917
2020 The extended UBA domain of UBXN1 specifically recognizes K6-linked diubiquitin: a C-terminally extended form of the UBA domain confers K6-linkage specificity, converging the two solution conformations of K6 diUb into a single conformation upon binding; the non-extended UBA domain does not show linkage preference. NMR spectroscopy with 15N-labeled synthetic diubiquitins, chemical shift perturbation, structural analysis Frontiers in chemistry High 32039147
2016 UBA-UBX proteins p47 and SAKS1 (UBXN1) have opposing roles in ERAD substrate degradation: p47 promotes degradation of α-TCR while SAKS1 delays it; SAKS1 selectively inhibits degradation of ERAD substrates without affecting cytosolic proteasomal substrates; expression of SAKS1 is reduced in cells stably expressing ERAD substrates and elevated upon ER stress. ERAD substrate degradation assays (α-TCR, α1-antitrypsin, δCD3), siRNA knockdown, pulse-chase/cycloheximide chase, stable cell lines expressing ERAD substrates Molecular and cellular biochemistry Medium 27785701
2024 UBXN1 promotes noncanonical inflammasome activation: together with unanchored K48/K63-linked polyubiquitin chains, UBXN1 binds caspase-4/11, promoting their assembly and activation; UBXN1 deficiency impairs caspase-4/11 activation, cytokine secretion, and pyroptosis in response to intracellular LPS; UBXN1-deficient mice are protected from LPS- and CLP-induced sepsis. Co-immunoprecipitation (UBXN1–caspase-4/11 interaction), KO cell lines and mice, inflammasome activation assays, recombinant USP5 depletion of unanchored polyUb, USP5 inhibitor experiments bioRxivpreprint Medium bio_10.1101_2024.10.30.621131
2024 UBR5 mediates Lys11-linked polyubiquitination and degradation of UBXN1 downstream of SUB1/PC4, thereby activating NF-κB signaling; SUB1 interacts with UBR5 and increases its protein level, leading to reduced UBXN1 and consequently elevated NF-κB activity. Co-immunoprecipitation (SUB1–UBR5 interaction), ubiquitination assays (Lys11 linkage), KO/knockdown, NF-κB reporter assays, in vivo tumor models Science China. Life sciences Medium 38240906
2021 YTHDF2 accelerates UBXN1 mRNA degradation via METTL3-mediated m6A modification, leading to reduced UBXN1 protein and consequent NF-κB activation; UBXN1 overexpression attenuates the oncogenic effect of YTHDF2 overexpression. RNA immunoprecipitation (RIP), methylated RIP (MeRIP), RNA stability assays, siRNA knockdown/overexpression, orthotopic xenograft models Journal of hematology & oncology Medium 34246306
2021 The lncRNA PRADX recruits the PRC2/DDX5 complex to the UBXN1 gene promoter, increasing H3K27 trimethylation and suppressing UBXN1 transcription, which in turn promotes NF-κB activity. ChIRP (chromatin isolation by RNA purification), ChIP, Co-IP, siRNA knockdown, H3K27me3 ChIP at UBXN1 promoter, xenograft models Theranostics Medium 33754075
2024 UBXN1 interacts with the inner mitochondrial membrane protein prohibitin (PHB) and sustains PHB expression; UBXN1 inhibition triggers mitochondrial damage and HCC cell apoptosis, indicating a role in maintaining mitochondrial homeostasis. Co-immunoprecipitation (UBXN1–PHB), KO/knockdown, apoptosis assays (TUNEL, FACS), mouse liver tumor models (Sleeping Beauty transposon) Journal of translational medicine Medium 38773518
2019 UBXN1 interacts with the TGEV coronavirus S1 spike protein and positively supports viral replication; UBXN1 knockdown reduces viral titer and S1 expression while overexpression increases viral copy number; UBXN1 negatively regulates IFN-β expression after TGEV infection. Yeast two-hybrid, GST pulldown, Co-immunoprecipitation, siRNA knockdown, overexpression, viral titer assays Veterinary research Low 31029162

Source papers

Stage 0 corpus · 23 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2021 YTHDF2 facilitates UBXN1 mRNA decay by recognizing METTL3-mediated m6A modification to activate NF-κB and promote the malignant progression of glioma. Journal of hematology & oncology 146 34246306
2013 UBXN1 interferes with Rig-I-like receptor-mediated antiviral immune response by targeting MAVS. Cell reports 58 23545497
2021 LncRNA PRADX-mediated recruitment of PRC2/DDX5 complex suppresses UBXN1 expression and activates NF-κB activity, promoting tumorigenesis. Theranostics 53 33754075
2010 The UBXN1 protein associates with autoubiquitinated forms of the BRCA1 tumor suppressor and inhibits its enzymatic function. Molecular and cellular biology 49 20351172
2016 The CRISPR/Cas9 system targeting EGFR exon 17 abrogates NF-κB activation via epigenetic modulation of UBXN1 in EGFRwt/vIII glioma cells. Cancer letters 36 27998759
2015 Ubiquitin-associated domain-containing ubiquitin regulatory X (UBX) protein UBXN1 is a negative regulator of nuclear factor κB (NF-κB) signaling. The Journal of biological chemistry 33 25681446
2021 VCP/p97 cofactor UBXN1/SAKS1 regulates mitophagy by modulating MFN2 removal from mitochondria. Autophagy 32 33966597
2010 The UBX protein SAKS1 negatively regulates endoplasmic reticulum-associated degradation and p97-dependent degradation. The Journal of biological chemistry 29 21135095
2018 The VCP-UBXN1 Complex Mediates Triage of Ubiquitylated Cytosolic Proteins Bound to the BAG6 Complex. Molecular and cellular biology 27 29685906
2021 CircMRE11A_013 binds to UBXN1 and integrates ATM activation enhancing lens epithelial cells senescence in age-related cataract. Aging 24 33508783
2021 The p97-UBXN1 complex regulates aggresome formation. Journal of cell science 19 33712450
2016 The opposite role of two UBA-UBX containing proteins, p47 and SAKS1 in the degradation of a single ERAD substrate, α-TCR. Molecular and cellular biochemistry 11 27785701
2024 UBXN1 maintains ER proteostasis and represses UPR activation by modulating translation. EMBO reports 8 38177917
2024 SUB1 promotes colorectal cancer metastasis by activating NF-κB signaling via UBR5-mediated ubiquitination of UBXN1. Science China. Life sciences 8 38240906
2025 The Oncogenic Role of UBXN1 in Gastric Cancer Is Attributed to the METTL16-Mediated m6A Methylation and Histone Modifications. Cancer medicine 5 40095756
2021 ARRDC4 and UBXN1: Novel Target Genes Correlated with Prostate Cancer Gleason Score. Cancers 5 34680357
2020 Diubiquitin-Based NMR Analysis: Interactions Between Lys6-Linked diUb and UBA Domain of UBXN1. Frontiers in chemistry 5 32039147
2019 UBXN1 interacts with the S1 protein of transmissible gastroenteritis coronavirus and plays a role in viral replication. Veterinary research 5 31029162
2024 UBXN1 promotes liver tumorigenesis by regulating mitochondrial homeostasis. Journal of translational medicine 4 38773518
2014 UBXN1 polymorphism and its expression in porcine M. longissimus dorsi are associated with water holding capacity. Molecular biology reports 3 24407602
2022 Uridine Diphosphate Glucuronosyl Transferase 2B28 (UGT2B28) Promotes Tumor Progression and Is Elevated in African American Prostate Cancer Patients. Cells 2 35954173
2026 Metabolic reprogramming-associated genomic instability drives colorectal cancer progression via the UBXN1-NF-κB axis. American journal of translational research 0 42007143
2021 UBXN1 is a strong candidate gene in regulation of pork water-holding capacity. Archives animal breeding 0 34084909

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