Affinage

NPLOC4

Nuclear protein localization protein 4 homolog · UniProt Q8TAT6

Length
608 aa
Mass
68.1 kDa
Annotated
2026-04-29
67 papers in source corpus 35 papers cited in narrative 39 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

NPLOC4 (Npl4) is an essential cofactor of the p97/VCP AAA-ATPase that, together with UFD1, forms a heterodimeric adaptor directing p97 segregase/unfoldase activity toward K48-polyubiquitinated substrates across diverse cellular pathways including ERAD, DNA replication termination (CMG helicase disassembly), mitotic chromosome segregation (Aurora B removal), G2/M checkpoint enforcement (CDC25A degradation), NF-κB signaling (IκBα processing), and ribosome-associated quality control (PMID:10811609, PMID:11739805, PMID:28355556, PMID:24248593, PMID:11847109). Structurally, NPLOC4 uses its UBL domain to contact the p97 N-domain, its MPN domain to bind UFD1, its NZF zinc finger to recognize ubiquitin via the Ile-44 hydrophobic patch, and its C-terminal domain to confer K48-linkage selectivity for polyubiquitin chains (PMID:17491009, PMID:12644454, PMID:31836717, PMID:36087575). Cryo-EM studies reveal that NPLOC4 undergoes nucleotide-dependent seesaw conformational changes on the p97 hexamer, driven by zinc-finger–N-domain interactions, that are essential for activating p97-mediated substrate unfolding; disruption of these dynamics by the disulfiram metabolite CuET, which releases cupric ions that damage the zinc-finger motifs, kills cancer cells preferentially deficient in BRCA1/BRCA2 (PMID:33402676, PMID:31391554). UBX-domain cofactors such as FAF1, UBXN7, and FAF2 further lower the ubiquitin-chain threshold for productive NPLOC4-UFD1–mediated substrate engagement, while the newly identified cofactor VCF1 stimulates UFD1-NPL4 interactions with ubiquitin conjugates through high-affinity p97 N-domain binding (PMID:35920641, PMID:38503733).

Mechanistic history

Synthesis pass · year-by-year structured walk · 12 steps
  1. 2000 High

    Establishing that mammalian Npl4 and Ufd1 form a stable heterodimer that binds p97 in competition with p47 resolved how p97 is directed to ubiquitin-dependent pathways distinct from membrane fusion.

    Evidence Biochemical fractionation of rat liver cytosol with co-immunoprecipitation and competition assays

    PMID:10811609

    Open questions at the time
    • Substrates of the p97-Ufd1-Npl4 complex were not yet identified
    • Stoichiometry of the ternary complex was unknown
    • No structural information on the heterodimer
  2. 2001 High

    Demonstrating that the Cdc48-Ufd1-Npl4 complex acts as a ubiquitin-selective segregase for both membrane-tethered transcription factors (Spt23/Mga2) and ERAD substrates established its dual role in substrate extraction upstream of the proteasome.

    Evidence Yeast genetic epistasis, in vivo ubiquitination assays, and temperature-sensitive mutant analysis across multiple studies

    PMID:11598205 PMID:11733065 PMID:11739805

    Open questions at the time
    • The mechanism of substrate threading/unfolding was unknown
    • Whether the complex directly contacts ubiquitin or recognizes substrates indirectly was unclear
  3. 2003 High

    Solving the NZF domain structure and showing it binds ubiquitin via the Ile-44 surface, combined with reconstituted retrotranslocation assays showing dual substrate recognition by p97 and Ufd1, defined the molecular basis of ubiquitin-dependent substrate engagement.

    Evidence NMR structure of the NZF domain; in vitro retrotranslocation assay with ATPase mutagenesis and ubiquitin-binding assays

    PMID:12644454 PMID:12847084

    Open questions at the time
    • How K48-linkage selectivity is achieved was not resolved by the NZF structure alone
    • The role of ATP hydrolysis cycles in powering extraction was modeled but not directly visualized
  4. 2007 High

    Determining the EM structure of the Ufd1-Npl4 heterodimer on p97 and the NMR structure of the Npl4 UBL domain binding the p97 N-domain revealed the quaternary architecture and domain-level contacts of the ternary complex.

    Evidence Electron microscopy reconstruction and NMR chemical shift perturbation mapping of the full hexameric complex

    PMID:17202270 PMID:17491009

    Open questions at the time
    • Atomic-resolution structure of the human ternary complex was still lacking
    • How nucleotide state modulates Npl4 positioning was not yet resolved
  5. 2011 High

    Showing that Ufd1-Npl4 mediates Aurora B removal from chromosomes during mitosis extended the complex's function beyond ERAD to mitotic regulation, explaining chromosome segregation defects upon its depletion.

    Evidence siRNA knockdown in HeLa cells with immunofluorescence, Aurora B activity assays, and live-cell imaging

    PMID:21486945

    Open questions at the time
    • The ubiquitin ligase responsible for Aurora B ubiquitination in this context was not identified
    • Whether this function requires specific UBX cofactors was unknown
  6. 2012 High

    Cryo-EM visualization of nucleotide-dependent conformational changes in p97-Ufd1-Npl4 and the identification of a SUMO-interaction motif in Ufd1 broadened understanding of substrate recognition to include SUMO-ubiquitin hybrid signals.

    Evidence Cryo-EM 3D reconstruction showing nucleotide-dependent repositioning; pulldown assays and genetic epistasis in fission yeast for SUMO binding

    PMID:22232657 PMID:22730331

    Open questions at the time
    • The precise conformational trajectory during substrate processing was not resolved at atomic level
    • Whether SUMO recognition by Ufd1 is conserved in mammals was untested
  7. 2013 High

    Identifying the p97-Ufd1-Npl4 complex as essential for IκBα proteolysis in NF-κB signaling and showing that FAF1 selectively associates with the VCP-Npl4-Ufd1 complex to enhance K48-ubiquitin binding expanded the pathway repertoire and introduced the concept of accessory cofactor modulation.

    Evidence Co-immunoprecipitation, siRNA knockdown, ATPase-dead mutant analysis, and structural analysis in mammalian cells

    PMID:23293021 PMID:24248593

    Open questions at the time
    • How FAF1 allosterically stimulates ubiquitin binding without direct UBA-UBX contact was structurally unresolved
    • The full spectrum of UBX cofactors modulating the complex was unknown
  8. 2017 High

    Reconstituting p97-Npl4-Ufd1 unfoldase activity in vitro with purified components and showing that CMG disassembly requires Ufd1-Npl4 recruitment to ubiquitinated Mcm7 provided the first direct biochemical proof of the complex's unfoldase mechanism and its role in replication termination.

    Evidence Reconstituted in vitro unfoldase assay with Ub-GFP substrate; yeast in vitro CMG disassembly assay with Mcm7 K29 mutagenesis

    PMID:28355556 PMID:28512218

    Open questions at the time
    • How the ubiquitin chain is threaded through the p97 pore was not yet visualized
    • Whether branched-chain preference reflects a general or substrate-specific mechanism was unclear
  9. 2019 High

    Crystal structures of Npl4 with K48-diubiquitin defined the structural basis of K48-linkage selectivity via the CTD, and identification of NPL4 as the target of the disulfiram metabolite CuET established a pharmacologically actionable vulnerability.

    Evidence X-ray crystallography with mutational analysis; cell viability and aggregation assays in cancer cell lines

    PMID:31391554 PMID:31836717

    Open questions at the time
    • Whether CuET-induced NPL4 aggregation is reversible was unknown
    • The structural mechanism by which CuET disrupts zinc fingers was not yet shown
  10. 2021 High

    Cryo-EM of the human p97-Npl4 complex resolved three pre-hydrolysis conformational states (seesaw motion) dependent on zinc-finger–N-domain interactions, and showed that CuET disrupts these dynamics by releasing cupric ions from zinc fingers, unifying the structural and pharmacological observations.

    Evidence Cryo-EM single-particle analysis with in vitro and cell-based functional assays

    PMID:33402676

    Open questions at the time
    • Conformational states during active substrate unfolding (post-hydrolysis) were not captured
    • How seesaw motion mechanically couples to substrate threading remains unresolved
  11. 2022 High

    Multiple studies established that UBX cofactors (UBXN7, FAF1, FAF2) lower the ubiquitin-chain threshold for productive unfolding, that SUMO-ubiquitin hybrid chains accelerate processing, and that the human Ufd1-Npl4 crystal structure defines atomic contacts, collectively refining the cofactor-modulated activation model.

    Evidence Reconstituted in vitro unfolding assays with purified human components; cryo-EM of SUMO-ubiquitin substrate engagement; X-ray crystallography of human Ufd1-Npl4 at 2.7 Å

    PMID:35920641 PMID:36087575 PMID:36574706

    Open questions at the time
    • How individual UBX cofactors are selected for specific substrates in vivo is unknown
    • Whether FAF2 coiled-coil function is conserved across species was not tested
  12. 2024 High

    Discovery of VCF1 as a high-affinity p97 N-domain binder that stimulates UFD1-NPL4 ubiquitin interactions, and identification of the p97-Npl4 axis in STAT3 degradation within tumor-infiltrating Tregs, extended the functional scope to immune regulation and revealed additional cofactor layers.

    Evidence Structure-function studies with binding and degradation assays; co-IP with inhibitor treatment and mouse tumor models

    PMID:38503733 PMID:39107403

    Open questions at the time
    • Whether VCF1 is constitutive or context-specific in vivo is unclear
    • The structural basis of thonzonium bromide's disruption of p97-Npl4 is not defined

Open questions

Synthesis pass · forward-looking unresolved questions
  • Key open questions include the full conformational trajectory of Npl4 during active substrate unfolding, how cofactor selection is coordinated in vivo to direct the complex to specific substrates, and whether Npl4 zinc-finger–targeted pharmacology can be developed with selectivity over other zinc-finger proteins.
  • No atomic-resolution structure of the human p97-Npl4-Ufd1 complex engaged with a substrate mid-translocation
  • Mechanism of cofactor hierarchy and competition in living cells is undefined
  • In vivo selectivity profile of CuET and related zinc-targeting agents is incompletely characterized

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 5 GO:0098772 molecular function regulator activity 3
Localization
GO:0005783 endoplasmic reticulum 3 GO:0005634 nucleus 2 GO:0005694 chromosome 2 GO:0005829 cytosol 2
Pathway
R-HSA-392499 Metabolism of proteins 6 R-HSA-1640170 Cell Cycle 3 R-HSA-168256 Immune System 2 R-HSA-69306 DNA Replication 2 R-HSA-73894 DNA Repair 2 R-HSA-8953897 Cellular responses to stimuli 2
Partners
FAF1FAF2NS4BTRIM21UBXN7UFD1LVCF1VCP
Complex memberships
RQC complex (Cdc48-Ufd1-Npl4 with Ltn1/Rqc1 on 60S ribosome)p97-UFD1-NPL4 (VCP-UFD1L-NPLOC4)

Evidence

Reading pass · 39 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2000 Mammalian UFD1 and NPL4 form a stable binary complex (Ufd1-Npl4 heterodimer) that binds to p97 AAA-ATPase and competes with the p47 adaptor for p97 binding, directing p97 to ubiquitin-dependent cellular functions distinct from Golgi membrane fusion. Biochemical fractionation of rat liver cytosol, co-immunoprecipitation, competition assays The EMBO journal High 10811609
2001 The yeast Cdc48(UFD1/NPL4) complex acts as a ubiquitin-selective chaperone/segregase that preferentially binds ubiquitinated substrates and liberates the processed, ubiquitinated transcription factor SPT23 (p90) from its membrane-tethered unprocessed partner for nuclear targeting. Genetic epistasis in yeast, co-immunoprecipitation, in vivo ubiquitination assays Cell High 11733065
2001 HRD4/NPL4 (yeast Npl4) is required for ERAD at a step after ubiquitination of ER substrates but before their recognition by the 26S proteasome, and each subunit of the Cdc48p-Ufd1p-Npl4p complex is individually required for ERAD. Temperature-sensitive yeast mutant analysis, direct ubiquitination assays, genetic epistasis Molecular biology of the cell High 11739805
2001 The Npl4p-Ufd1p-Cdc48p complex mediates proteasome-dependent processing of the membrane-bound transcription factors Mga2p and Spt23p; mutations in NPL4, UFD1, or CDC48 block their proteolytic cleavage and abolish OLE1 expression. Yeast genetics, reporter assays, epistasis analysis Molecular biology of the cell High 11598205
2002 The yeast CDC48(UFD1/NPL4) complex functions as a segregase to mediate ERAD of OLE1 itself, liberating ubiquitylated proteins from non-modified partners; it is a constitutive component of the ERAD machinery. Yeast genetics, in vivo ubiquitination assays, ERAD substrate stability assays The EMBO journal High 11847109
2003 The p97-Ufd1-Npl4 complex drives retrotranslocation of ubiquitinated ER substrates via dual substrate recognition: the p97 D1 ATPase domain (in nucleotide-bound state) binds non-ubiquitinated polypeptide segments emerging from the ER membrane, while polyubiquitin chains (K48-linked) are synergistically recognized by both p97 and a conserved ubiquitin-binding site at the N-terminus of Ufd1; alternating ATP hydrolysis by D1 and D2 domains powers substrate extraction. In vitro retrotranslocation assay, ATPase domain mutagenesis, ubiquitin-binding assays, dominant-negative p97 constructs The Journal of cell biology High 12847084
2003 The Npl4 zinc finger (NZF) domain adopts a compact four-antiparallel beta-strand structure with a single zinc coordinated by four cysteines in two rubredoxin knuckles; it binds specifically but weakly to free ubiquitin via a conserved 13TF14 dipeptide that contacts the Ile-44 surface of ubiquitin. NMR solution structure determination, ubiquitin-binding assays The Journal of biological chemistry High 12644454
2005 The p97-Ufd1-Npl4 complex associates with ubiquitinated IP3 receptors in mammalian cells in response to hormonal stimulation and couples ubiquitinated IP3 receptors to proteasomal degradation; RNAi knockdown of p97 markedly retards IP3 receptor degradation and causes ubiquitinated IP3 receptor accumulation. Co-immunoprecipitation, RNA interference in mammalian cells, IP3 receptor degradation assays The Journal of biological chemistry High 16103111
2007 The Ufd1-Npl4 heterodimer has an elongated bilobed structure (~80×30 Å); one Ufd1-Npl4 heterodimer interacts with one p97 hexamer, emanating from the periphery of the N-D1 plane; the p97-Ufd1-Npl4 and p97-p47 complexes differ significantly in stoichiometry, symmetry, and quaternary arrangement. Electron microscopy and biophysical techniques (EM, biochemical) Proceedings of the National Academy of Sciences of the United States of America High 17202270
2007 The Npl4 ubiquitin-like (UBL) domain adopts a beta-grasp fold with a 3(10) helical insert and binds the p97 N-domain; the p97 N-domain also contacts the p97-binding region of Ufd1; NMR chemical shift perturbation mapping of the full p97-UN hexamer complex reveals an identical mode of interaction. NMR solution structure, chemical shift perturbation analysis, structural modeling The Journal of biological chemistry High 17491009
2008 Ufd1 binding to Npl4 in mammalian cells is mediated by two regions: a conserved stretch (aa 113-255) within the zf-Npl4 domain and the Npl4 homology domain (aa 263-344); within the first region, distinct subdomains mediate Ufd1 binding and regulate VCP binding separately. Npl4 deletion mutant analysis, co-immunoprecipitation in mammalian cells Experimental cell research Medium 18586029
2010 MHC class I heavy chain retrotranslocation in US2-expressing cells requires p97 ATPase but is independent of the Ufd1-Npl4 cofactor, demonstrating that p97 can employ distinct adaptor complexes for different retrotranslocation substrates. In vitro permeabilized cell retrotranslocation assay, immunodepletion of Ufd1-Npl4 The Journal of biological chemistry High 20702414
2011 In HeLa cells, Ufd1-Npl4 (as part of Cdc48/p97 complex) removes Aurora B kinase from chromosomes during prometaphase and metaphase; siRNA depletion of Ufd1-Npl4 increases Aurora B levels and activity on chromosomes, causing chromosome alignment and anaphase defects, missegregated chromosomes, and multi-lobed nuclei. siRNA knockdown in HeLa cells, immunofluorescence, Aurora B activity assays, live-cell imaging Journal of cell science High 21486945
2012 p97-Ufd1-Npl4 adopts distinct conformations relative to the p97 ring upon nucleotide addition, as revealed by cryo-EM; Ufd1-Npl4 is highly dynamic and changes position on p97 in a nucleotide-dependent manner, suggesting a model for substrate remodeling. Cryo-electron microscopy 3D reconstruction Proceedings of the National Academy of Sciences of the United States of America High 22232657
2012 The Cdc48-Ufd1-Npl4 segregase is recruited to STUbL targets via dual recognition: Ufd1 contains a SUMO interaction motif enabling SUMO binding in addition to ubiquitin binding, allowing the complex to act as a receptor for substrates modified with both SUMO and ubiquitin. Pulldown/binding assays, genetic epistasis in fission yeast, DNA repair functional assays The Journal of biological chemistry Medium 22730331
2013 FAF1 interacts specifically with VCP/p97 complexed with Npl4-Ufd1 (not with free VCP); the UBX domain of FAF1 binds VCP-Npl4-Ufd1 and the UBA domain binds K48-linked polyubiquitinated proteins; VCP association via UBX regulates ubiquitin binding to UBA without direct UBA-UBX contact, promoting ERAD. Co-immunoprecipitation, structural analysis, biochemical assays The Journal of biological chemistry High 23293021
2013 The p97-UFD1L-NPL4 complex mediates cytokine-induced IκBα proteolysis: it associates with ubiquitinated IκBα via interactions between p97 and SCF(β-TRCP) and between the polyubiquitin-binding domain of UFD1L and polyubiquitinated IκBα; p97 ATPase activity is essential; NPL4 and UFD1L are required cofactors for this NF-κB activation mechanism. Co-immunoprecipitation, siRNA knockdown, ATPase-dead mutant analysis in mammalian cells Molecular and cellular biology High 24248593
2013 NUB1L promotes proteasomal degradation of NEDD8 and neddylation by directly interacting with NEDD8 (at residue Asn-51) and with p97/VCP; in coordination with the P97-UFD1-NPL4 complex, NUB1L facilitates transfer of NEDD8 to the proteasome. Co-immunoprecipitation, in vitro binding assays, mutagenesis The Journal of biological chemistry Medium 24019527
2014 The p97-Ufd1-Npl4 complex functions in G2/M checkpoint signaling by binding CDC25A downstream of SCF-βTrCP ubiquitination and facilitating its proteasomal degradation; depletion of Ufd1-Npl4 causes G2/M checkpoint failure, persistent CDC25 activity, and propagation of DNA damage into mitosis. siRNA depletion in human cells, co-immunoprecipitation, cell cycle analysis, DNA damage assays Cell cycle Medium 24429874
2017 Wild-type p97 in complex with NPLOC4-UFD1L can unfold ubiquitinated proteins (Ub-GFP substrate with K48-linked chains) in vitro; this unfoldase activity requires ATP hydrolysis, the NPLOC4-UFD1L adaptor, and substrate ubiquitination; branched chains provide maximal stimulation; a multisystem proteinopathy (MSP) p97 mutant unfolds substrate faster, indicating gain-of-function. Reconstituted in vitro unfoldase assay with purified components, ATPase inhibitor, mutagenesis Proceedings of the National Academy of Sciences of the United States of America High 28512218
2017 In yeast, Ufd1-Npl4 recruits Cdc48 to ubiquitylated CMG helicase (ubiquitinated on Mcm7-K29) at the end of chromosome replication to drive CMG disassembly; mutation of Mcm7 K29 abolishes Ufd1-Npl4-Cdc48 recruitment and CMG disassembly. Yeast genetics, in vitro ubiquitylation and disassembly assays, mutagenesis Cell reports High 28355556
2019 Crystal structures of yeast Npl4 in complex with K48-linked diubiquitin reveal that the distal ubiquitin interacts with the C-terminal helix and the proximal ubiquitin interacts with the N-terminal loop of the Npl4 C-terminal domain (CTD); the CTD contributes to K48-linkage selectivity; Ufd1 occupies a hydrophobic groove of the Npl4 MPN domain corresponding to the catalytic groove of JAMM-family DUBs. X-ray crystallography, mutational analysis Nature communications High 31836717
2019 All seven analyzed MSP mutants of p97 exhibit tighter NPLOC4·UFD1L (UN) binding and faster substrate unfolding; cryo-EM structural analysis suggests increased UN affinity originates from decoupling of p97 nucleotide state and N-terminal domain positioning, supporting a gain-of-function model. Cryo-EM, biochemical unfolding assays, binding assays Structure High 31623962
2019 The anticancer metabolite of disulfiram, bis-(diethyldithiocarbamate)-copper complex (CuET), kills cancer cells by causing aggregation of NPL4, a subunit of the p97/VCP segregase, rather than by inhibiting ALDH; CuET-mediated cytotoxicity is preferential towards BRCA1/BRCA2-deficient cells. Cell viability assays, NPL4 aggregation assays, biochemical validation in human cancer cell lines Oncogene High 31391554
2021 Cryo-EM of the human p97-Npl4 complex reveals three Npl4 conformational states before ATP hydrolysis; Npl4 motion (seesaw conformations) results from zinc finger motifs interacting with the N-domain of p97, which is essential for p97 unfolding activity; CuET releases cupric ions under oxidative conditions that disrupt Npl4 zinc finger motifs, locking the conformational switch and inhibiting p97 function. Cryo-EM single-particle analysis, in vitro and cell-based functional assays Nature communications High 33402676
2022 Multiple UBX proteins (UBXN7, FAF1, FAF2) reduce the ubiquitin threshold of mammalian p97-UFD1-NPL4 for substrate unfolding by binding to p97-UFD1-NPL4 and stabilizing productive interactions between UFD1-NPL4 and K48-linked chains of at least five ubiquitins; FAF2 uses a previously uncharacterized coiled-coil domain for this stimulation; deleting Ubxn7 and Faf1 impairs CMG disassembly during S-phase and mitosis. Reconstituted in vitro unfolding assays with purified human components, yeast genetics, cell biology eLife High 35920641
2022 SUMO modifications on substrates enhance their unfolding by the Ufd1/Npl4/Cdc48 complex: Ufd1 interactions with SUMO on SUMO-polyubiquitin hybrid chains accelerate substrate unfolding compared to polyubiquitin alone; cryo-EM structures reveal features of Ufd1/Npl4/Cdc48 interactions with ubiquitin prior to and during unfolding. Reconstituted in vitro unfolding assays, cryo-EM single-particle analysis Proceedings of the National Academy of Sciences of the United States of America High 36574706
2022 In Saccharomyces cerevisiae, Cdc48-Ufd1-Npl4 segregase facilitates removal of polyubiquitinated, mislocalized Cse4 (CENP-A) from non-centromeric chromatin; Npl4 (the ubiquitin-binding receptor) associates with mislocalized Cse4 in a Psh1-mediated polyubiquitination-dependent manner. Yeast genetics, co-immunoprecipitation, chromatin immunoprecipitation, ChIP Nucleic acids research Medium 35234920
2022 Flavivirus nonstructural protein NS4B directly interacts with NPL4 and recruits the VCP-NPL4 complex to viral replication sites; NPL4 depletion impairs early viral genome replication; the VCP-NPL4 interaction is required (among 17 VCP cofactor mutants tested) for Japanese encephalitis virus replication and for stress granule disassembly. siRNA rescue experiments with VCP cofactor mutants, co-immunoprecipitation, viral replication assays The Journal of biological chemistry Medium 35063505
2022 Crystal structure of the human Ufd1-Npl4 (UN) heterodimer at 2.7 Å and hNpl4 alone at 3.0 Å reveal atomic details of the human UN complex; site-directed mutagenesis of hUfd1 residues at the hNpl4 interface identifies key contacts. X-ray crystallography, site-directed mutagenesis Structure High 36087575
2023 A conserved cysteine C115 at the Cdc48 N-terminal domain (NTD)-Npl4 binding interface is central to stability of the Cdc48-Npl4-Ufd1 ternary complex; binding of the Cdc48 NTD stabilizes UN assembly; C115S mutation disrupts NTD-Npl4-Ufd1 interaction and reduces cellular growth and protein quality control in yeast. Integrative structural modeling, crosslinking mass spectrometry (XL-MS), mutagenesis, yeast cell biology Structure High 37311459
2024 VCF1 (FAM104A) is a p97 cofactor that directly binds the p97 N-domain via a conserved α-helical motif with unusually high affinity, engages in joint p97 complex formation with UFD1-NPL4, and indirectly stimulates UFD1-NPL4 interactions with K48-linked ubiquitin conjugates via p97 binding, promoting p97-UFD1-NPL4-dependent proteasomal degradation. Co-immunoprecipitation, pulldown assays, structure-function studies, ubiquitin-binding assays, cell-based degradation assays Nature communications High 38503733
2024 The p97-Npl4 complex bridges STAT3 with E3 ligases PDLIM2 and PDLIM5 in tumor-infiltrating regulatory T cells, promoting STAT3 ubiquitin-mediated degradation and enabling TI-Treg cell development; pharmacological disruption of the p97-Npl4 interaction by thonzonium bromide inhibits TI-Treg cell development and boosts antitumor immunity. Co-immunoprecipitation, inhibitor treatment, mouse tumor models, T cell functional assays Nature immunology Medium 39107403
2024 VCP/p97 is recruited to non-cytosolic compartments during oxidative stress in a ubiquitin-dependent manner mediated by its adaptor NPLOC4; VCP and NPLOC4 activities maintain low levels of non-cytosolic K63-linked ubiquitin chains, supporting a cyclical ubiquitin conjugation/removal model disrupted by reactive oxygen species. Subcellular ubiquitin proteomics, fractionation, siRNA knockdown, mammalian cells bioRxiv (preprint)preprint Low
2024 NPLOC4 interacts with ERO1α and its knockdown increases ERO1α expression, disrupts mitochondria-associated membranes (MAMs), modulates the β-catenin/GSK3β pathway, enhances mitochondrial dynamics and mitophagy, and reduces ROS in cardiomyocytes. STRING prediction validated by co-immunoprecipitation, knockdown experiments in H9c2 cells and TAC mouse model International immunopharmacology Low 39332095
2025 Faf1 accelerates ubiquitin-dependent substrate processing by p97-Ufd1-Npl4 by promoting unfolding of an initiator ubiquitin and its engagement by the ATPase motor; the p97-bound C-terminal UBX domain of Faf1 anchors a long helix that braces the UT3 domain of Ufd1, stabilizing the Ufd1-Npl4 cofactor for ubiquitin unfolding. Reconstituted in vitro biochemical assays, mutagenesis, FRET-based assays, cryo-EM structure determination bioRxiv (preprint)preprint High
2025 Cryo-ET in situ imaging of polyQ aggregates shows VCP predominantly adopts an ATP-bound state, often in an active processing conformation with resolved NPLOC4-like cofactor density, near non-fibrillar polyQ intermediates; VCP couples directly to the 20S proteasome core via its C-terminal HbYX motif in a manner confirmed by cryo-EM SPA and in vitro assays. In situ cryo-ET subtomogram averaging, cryo-EM single-particle analysis, in vitro assays bioRxiv (preprint)preprint Medium
2025 Cryo-EM structure of the RQC complex shows that Cdc48-Ufd1-Npl4 is recruited by the Ltn1 E3 ubiquitin ligase to extract ubiquitylated stalled peptides from the 60S ribosome; Rqc1 bridges the 60S ribosome with ubiquitin and Ltn1, facilitating K48-linked polyubiquitin chain formation on stalled peptides. Cryo-EM structure of the budding yeast RQC complex bioRxiv (preprint)preprint Medium
2024 Trim21 E3 ubiquitin ligase interacts with UFD1, facilitates K27-linked ubiquitination of UFD1, and inhibits UFD1 incorporation into the VCP/Npl4/UFD1 complex, thereby suppressing ERAD substrate degradation and activating a proapoptotic UPR. Co-immunoprecipitation, ubiquitination assays, ERAD substrate stability assays in cancer cells Biochimica et biophysica acta. Molecular basis of disease Medium 39368714

Source papers

Stage 0 corpus · 67 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2003 Function of the p97-Ufd1-Npl4 complex in retrotranslocation from the ER to the cytosol: dual recognition of nonubiquitinated polypeptide segments and polyubiquitin chains. The Journal of cell biology 503 12847084
2000 A complex of mammalian ufd1 and npl4 links the AAA-ATPase, p97, to ubiquitin and nuclear transport pathways. The EMBO journal 384 10811609
2001 Mobilization of processed, membrane-tethered SPT23 transcription factor by CDC48(UFD1/NPL4), a ubiquitin-selective chaperone. Cell 372 11733065
2002 Role of the ubiquitin-selective CDC48(UFD1/NPL4 )chaperone (segregase) in ERAD of OLE1 and other substrates. The EMBO journal 278 11847109
2001 HRD4/NPL4 is required for the proteasomal processing of ubiquitinated ER proteins. Molecular biology of the cell 249 11739805
2017 Ubiquitin- and ATP-dependent unfoldase activity of P97/VCP•NPLOC4•UFD1L is enhanced by a mutation that causes multisystem proteinopathy. Proceedings of the National Academy of Sciences of the United States of America 153 28512218
2001 The conserved npl4 protein complex mediates proteasome-dependent membrane-bound transcription factor activation. Molecular biology of the cell 134 11598205
2002 Cdc48-Ufd1-Npl4: stuck in the middle with Ub. Current biology : CB 132 12015140
2003 Structure and ubiquitin interactions of the conserved zinc finger domain of Npl4. The Journal of biological chemistry 130 12644454
2019 Disulfiram's anti-cancer activity reflects targeting NPL4, not inhibition of aldehyde dehydrogenase. Oncogene 96 31391554
2011 Specific recognition of linear ubiquitin chains by the Npl4 zinc finger (NZF) domain of the HOIL-1L subunit of the linear ubiquitin chain assembly complex. Proceedings of the National Academy of Sciences of the United States of America 92 22139374
2021 Seesaw conformations of Npl4 in the human p97 complex and the inhibitory mechanism of a disulfiram derivative. Nature communications 87 33402676
2007 Structural insights into the p97-Ufd1-Npl4 complex. Proceedings of the National Academy of Sciences of the United States of America 80 17202270
2012 Dual recruitment of Cdc48 (p97)-Ufd1-Npl4 ubiquitin-selective segregase by small ubiquitin-like modifier protein (SUMO) and ubiquitin in SUMO-targeted ubiquitin ligase-mediated genome stability functions. The Journal of biological chemistry 75 22730331
2019 Multisystem Proteinopathy Mutations in VCP/p97 Increase NPLOC4·UFD1L Binding and Substrate Processing. Structure (London, England : 1993) 57 31623962
1996 Nuclear transport defects and nuclear envelope alterations are associated with mutation of the Saccharomyces cerevisiae NPL4 gene. Molecular biology of the cell 57 8930904
2007 Detailed structural insights into the p97-Npl4-Ufd1 interface. The Journal of biological chemistry 55 17491009
2013 Complex of Fas-associated factor 1 (FAF1) with valosin-containing protein (VCP)-Npl4-Ufd1 and polyubiquitinated proteins promotes endoplasmic reticulum-associated degradation (ERAD). The Journal of biological chemistry 53 23293021
2011 Cdc48/p97-Ufd1-Npl4 antagonizes Aurora B during chromosome segregation in HeLa cells. Journal of cell science 48 21486945
2022 Disulfiram/Copper induces antitumor activity against gastric cancer via the ROS/MAPK and NPL4 pathways. Bioengineered 45 35290151
2005 Involvement of the p97-Ufd1-Npl4 complex in the regulated endoplasmic reticulum-associated degradation of inositol 1,4,5-trisphosphate receptors. The Journal of biological chemistry 44 16103111
2012 Distinct conformations of the protein complex p97-Ufd1-Npl4 revealed by electron cryomicroscopy. Proceedings of the National Academy of Sciences of the United States of America 40 22232657
2017 Ufd1-Npl4 Recruit Cdc48 for Disassembly of Ubiquitylated CMG Helicase at the End of Chromosome Replication. Cell reports 39 28355556
2013 The p97-UFD1L-NPL4 protein complex mediates cytokine-induced IκBα proteolysis. Molecular and cellular biology 39 24248593
2019 Structural insights into ubiquitin recognition and Ufd1 interaction of Npl4. Nature communications 37 31836717
2020 Targeting the NPL4 Adaptor of p97/VCP Segregase by Disulfiram as an Emerging Cancer Vulnerability Evokes Replication Stress and DNA Damage while Silencing the ATR Pathway. Cells 36 32085572
2019 A commonly occurring genetic variant within the NPLOC4-TSPAN10-PDE6G gene cluster is associated with the risk of strabismus. Human genetics 35 31073882
2015 Proteomics of yeast telomerase identified Cdc48-Npl4-Ufd1 and Ufd4 as regulators of Est1 and telomere length. Nature communications 35 26365526
2015 Targeting of SUMO substrates to a Cdc48-Ufd1-Npl4 segregase and STUbL pathway in fission yeast. Nature communications 34 26537787
2006 Destabilization of the VCP-Ufd1-Npl4 complex is associated with decreased levels of ERAD substrates. Experimental cell research 34 16822501
2022 Anticancer effects of disulfiram in T-cell malignancies through NPL4-mediated ubiquitin-proteasome pathway. Journal of leukocyte biology 29 35363385
2010 The p97 ATPase dislocates MHC class I heavy chain in US2-expressing cells via a Ufd1-Npl4-independent mechanism. The Journal of biological chemistry 27 20702414
2020 Targeting NPL4 via drug repositioning using disulfiram for the treatment of clear cell renal cell carcinoma. PloS one 25 32667929
2016 Differential Involvement of the Npl4 Zinc Finger Domains of SHARPIN and HOIL-1L in Linear Ubiquitin Chain Assembly Complex-Mediated Cell Death Protection. Molecular and cellular biology 24 26976635
2007 The AAA-ATPase p97-Ufd1-Npl4 is required for ERAD but not for spindle disassembly in Xenopus egg extracts. Journal of cell science 24 17374636
2022 Multiple UBX proteins reduce the ubiquitin threshold of the mammalian p97-UFD1-NPL4 unfoldase. eLife 23 35920641
2013 NEDD8 ultimate buster-1 long (NUB1L) protein promotes transfer of NEDD8 to proteasome for degradation through the P97UFD1/NPL4 complex. The Journal of biological chemistry 23 24019527
2022 SUMO enhances unfolding of SUMO-polyubiquitin-modified substrates by the Ufd1/Npl4/Cdc48 complex. Proceedings of the National Academy of Sciences of the United States of America 20 36574706
2022 Flavivirus recruits the valosin-containing protein-NPL4 complex to induce stress granule disassembly for efficient viral genome replication. The Journal of biological chemistry 19 35063505
2004 The Cdc48/p97-Ufd1-Npl4 complex: its potential role in coordinating cellular morphogenesis during the M-G1 transition. Cell cycle (Georgetown, Tex.) 16 15004522
2022 Cdc48Ufd1/Npl4 segregase removes mislocalized centromeric histone H3 variant CENP-A from non-centromeric chromatin. Nucleic acids research 15 35234920
2014 The p97-Ufd1-Npl4 ATPase complex ensures robustness of the G2/M checkpoint by facilitating CDC25A degradation. Cell cycle (Georgetown, Tex.) 15 24429874
2023 Overcoming the compensatory increase in NRF2 induced by NPL4 inhibition enhances disulfiram/copper-induced oxidative stress and ferroptosis in renal cell carcinoma. European journal of pharmacology 14 37838104
2021 Disulfiram and copper combination therapy targets NPL4, cancer stem cells and extends survival in a medulloblastoma model. PloS one 14 34731160
2024 Targeting p97-Npl4 interaction inhibits tumor Treg cell development to enhance tumor immunity. Nature immunology 13 39107403
2010 The Cdc48-Ufd1-Npl4 complex is central in ubiquitin-proteasome triggered catabolite degradation of fructose-1,6-bisphosphatase. Biochemical and biophysical research communications 13 20206597
2022 The p97-Nploc4 ATPase complex plays a role in muscle atrophy during cancer and amyotrophic lateral sclerosis. Journal of cachexia, sarcopenia and muscle 12 35611892
2019 Upregulation of NPL4 promotes bladder cancer cell proliferation by inhibiting DXO destabilization of cyclin D1 mRNA. Cancer cell international 12 31164795
2016 Evaluating p97 Inhibitor Analogues for Potency against p97-p37 and p97-Npl4-Ufd1 Complexes. ChemMedChem 12 27043824
2011 Cdc48 and cofactors Npl4-Ufd1 are important for G1 progression during heat stress by maintaining cell wall integrity in Saccharomyces cerevisiae. PloS one 12 21526151
2008 Analysis of Npl4 deletion mutants in mammalian cells unravels new Ufd1-interacting motifs and suggests a regulatory role of Npl4 in ERAD. Experimental cell research 12 18586029
2017 Roles for the VCP co-factors Npl4 and Ufd1 in neuronal function in Drosophila melanogaster. Journal of genetics and genomics = Yi chuan xue bao 11 29037990
2009 Ssz1 restores endoplasmic reticulum-associated protein degradation in cells expressing defective cdc48-ufd1-npl4 complex by upregulating cdc48. Genetics 11 20038635
2022 Structural basis for the interaction between human Npl4 and Npl4-binding motif of human Ufd1. Structure (London, England : 1993) 8 36087575
2001 Cloning and characterization of the gene encoding human NPL4, a protein interacting with the ubiquitin fusion-degradation protein (UFD1L). Gene 7 11574150
2024 VCF1 is a p97/VCP cofactor promoting recognition of ubiquitylated p97-UFD1-NPL4 substrates. Nature communications 6 38503733
2024 NPLOC4 aggravates heart failure by regulating ROS and mitochondrial function. International immunopharmacology 4 39332095
2023 Identification of novel dithiocarbamate-copper complexes targeting p97/NPL4 pathway in cancer cells. European journal of medicinal chemistry 4 37690264
2024 Trim21 modulates endoplasmic reticulum-associated degradation and sensitizes cancer cells to ER stress-induced apoptosis by inhibiting VCP/Npl4/UFD1 assembly. Biochimica et biophysica acta. Molecular basis of disease 3 39368714
2023 The Cdc48 N-terminal domain has a molecular switch that mediates the Npl4-Ufd1-Cdc48 complex formation. Structure (London, England : 1993) 3 37311459
2023 Comparison of force fields to study the zinc-finger containing protein NPL4, a target for disulfiram in cancer therapy. Biochimica et biophysica acta. Proteins and proteomics 2 37230374
2025 [64Cu]Cu(DDC)2 NPs: A Novel PET Probe for Noninvasive Visualization of NPL4 Expression in Tumors In Vivo. Molecular pharmaceutics 1 39927715
2026 NPLOC4 Inhibition Remodels Tumor Microenvironment via M2-to-M1 Macrophage Reprogramming and Boosts Anti-PD-1 Response in Liver Cancer. International journal of biological sciences 0 41800259
2026 Quantum Chemical Topology Analysis of Covalent Interactions in the Hydration of F- along with the Zinc Finger of NPL4 and Its Application to the Delimitation of QM/MM Boundaries. ACS omega 0 41939387
2025 A novel feedback regulation loop of METTL11A-MAFG-NPL4 promotes bladder cancer cell proliferation and tumor progression. FASEB journal : official publication of the Federation of American Societies for Experimental Biology 0 40171788
2025 FERONIA interacts with NPL4 to regulate immunity gene mRNA nucleocytoplasmic transport in response to plant immunity. Plant science : an international journal of experimental plant biology 0 40348341
2025 NPLOC4 constructs tumor immunosuppressive microenvironment in pan-cancer and hepatocellular carcinoma. Current medicinal chemistry 0 40685720