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Showing PSMD8 — RPN12 is a alias.

PSMD8

26S proteasome non-ATPase regulatory subunit 8 · UniProt P48556

Length
350 aa
Mass
39.6 kDa
Annotated
2026-06-10
43 papers in source corpus 8 papers cited in narrative 9 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

PSMD8 (Rpn12/Nin1p) is an essential subunit of the 19S regulatory particle of the 26S proteasome that links the regulatory particle to ubiquitin-dependent substrate recognition and proteolysis (PMID:7621825). The protein adopts a PCI-domain fold whose surface site mediates recruitment of the ubiquitin receptor Rpn10 to the 19S lid; mutation of this surface impairs Rpn10 binding in vitro and reduces Rpn10 incorporation into proteasomes in vivo (PMID:22906049). Structurally, PSMD8 directly engages the UIM of Rpn10 with an affinity comparable to Lys48-linked diubiquitin, allowing it to compete with ubiquitin for the Rpn10 receptor and thereby modulate substrate engagement (PMID:20739285). This recruitment is functionally tied to polyubiquitin substrate recognition, as the polyubiquitin-binding activity of the Rpn10 ortholog becomes essential when PSMD8 function is compromised (PMID:10809753), and PSMD8 also functionally cooperates with the base ATPase Rpt1 (PMID:10503546). Through its role in proteasome-dependent proteolysis, PSMD8 acts upstream of Cdc28/Cdk1 activation in cell cycle progression (PMID:7621825), and a null mutant studied in C. elegans further reveals a non-catalytic role independent of bulk proteasome proteolytic activity, affecting germline sex determination and nuclear localization of the meiotic kinase WEE-1.3 (PMID:32767462). In human cancer cells, PSMD8 directly interacts with and stabilizes the ferroptosis suppressor SLC7A11 in cooperation with USP14, suppressing ferroptosis and modulating cisplatin sensitivity in bladder cancer (PMID:41403840).

Mechanistic history

Synthesis pass · year-by-year structured walk · 9 steps
  1. 1995 High

    Established that PSMD8/Nin1p is a bona fide component of the 26S proteasome required for ubiquitin-dependent proteolysis, defining the molecular machine in which the protein operates.

    Evidence Glycerol density gradient co-sedimentation with the 26S peak and polyubiquitin accumulation in nin1-1 mutants in yeast

    PMID:7621825

    Open questions at the time
    • Did not resolve which subparticle (base vs lid) the protein belongs to
    • No direct binding partners within the complex identified
  2. 1995 Medium

    Connected proteasome function via PSMD8 to cell cycle control by placing it upstream of Cdc28/Cdk1 activation.

    Evidence Synthetic lethality with cdc28 alleles and failure to activate Cdc28 histone H1 kinase activity in yeast

    PMID:7621825

    Open questions at the time
    • Specific proteolytic substrate linking PSMD8 to Cdc28 activation not identified
    • Genetic interaction does not establish direct physical mechanism
  3. 1999 Medium

    Positioned PSMD8 in a functional relationship with the 19S base ATPase Rpt1, hinting at coordination between lid and base activities.

    Evidence Synthetic lethality of rpn12-1 with rpt1-2 in double-mutant analysis in yeast

    PMID:10503546

    Open questions at the time
    • Single method (genetic) without biochemical demonstration of physical contact
    • Mechanism of Rpt1 cooperation unresolved
  4. 2000 High

    Demonstrated functional cooperation between PSMD8/Rpn12 and the ubiquitin receptor Rpn10 in polyubiquitin substrate recognition.

    Evidence In vitro binding of Mts3 to Pus1 and genetic synthetic lethality/overexpression rescue requiring Pus1 polyubiquitin-binding activity in fission yeast

    PMID:10809753

    Open questions at the time
    • Structural basis of the interaction not yet defined
    • Whether interaction modulates or competes with ubiquitin binding unclear at this stage
  5. 2010 High

    Defined the biophysical nature of the PSMD8–Rpn10 interaction, showing it targets the Rpn10 UIM and can compete with ubiquitin.

    Evidence Crystal structure of Rpn10 vWA domain and NMR characterization of the UIM–Rpn12 interaction with affinity measurement in S. pombe

    PMID:20739285

    Open questions at the time
    • Functional consequence of ubiquitin competition in vivo not measured
    • Did not define the PSMD8 surface mediating the contact
  6. 2012 High

    Identified the PCI-domain structural basis by which PSMD8 recruits Rpn10 into the 19S lid.

    Evidence Crystal structure of Rpn12, surface-site mutagenesis, in vitro binding and in vivo Rpn10 incorporation assays in yeast

    PMID:22906049

    Open questions at the time
    • Dynamics of Rpn10 incorporation during proteasome assembly not resolved
    • Conservation of the surface site in human PSMD8 not tested
  7. 2020 Medium

    Revealed a proteasome-independent, non-catalytic role for PSMD8 in germline development and kinase localization, expanding its functions beyond bulk proteolysis.

    Evidence rpn-12 null mutant analysis, RNAi epistasis with tra-1, proteasome activity assays, and WEE-1.3 localization imaging in C. elegans

    PMID:32767462

    Open questions at the time
    • Molecular mechanism for the non-catalytic effect on WEE-1.3 unknown
    • Whether this role generalizes beyond the worm germline untested
  8. 2020 Low

    Provided NMR structural framework defining PSMD8 domain architecture (N-terminal TPR-like and C-terminal WH domains).

    Evidence NMR backbone resonance assignment of S. cerevisiae Rpn12

    PMID:32072453

    Open questions at the time
    • Assignments alone without functional validation of interactions in the same study
    • No interaction mapping derived from the assignments
  9. 2025 Medium

    Extended PSMD8 function to human cancer biology, showing it stabilizes the ferroptosis suppressor SLC7A11 and modulates chemosensitivity.

    Evidence Co-IP, knockdown with ferroptosis/apoptosis assays, and protein stability assays in bladder cancer cells; USP14 cooperation shown

    PMID:41403840

    Open questions at the time
    • Single Co-IP-based study without reciprocal structural validation
    • Mechanism by which PSMD8 stabilizes SLC7A11 (proteasomal vs non-proteasomal) not resolved
    • Whether this is independent of canonical proteasome assembly role unclear

Open questions

Synthesis pass · forward-looking unresolved questions
  • How PSMD8's canonical proteasome-assembly/Rpn10-recruitment role mechanistically relates to its emerging non-catalytic substrate-stabilizing functions remains unresolved.
  • No structural model of human PSMD8 bound to SLC7A11
  • Whether SLC7A11 stabilization requires intact 26S proteasome unknown
  • Direct ubiquitin-receptor recruitment role in human cells untested

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 3 GO:0005198 structural molecule activity 2
Pathway
R-HSA-392499 Metabolism of proteins 2 R-HSA-1640170 Cell Cycle 1
Partners
PSMC2PSMD4SLC7A11USP14
Complex memberships
19S regulatory particle (lid)26S proteasome

Evidence

Reading pass · 9 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1995 Nin1p (yeast ortholog of PSMD8/p31) is a component of the 26S proteasome complex, as demonstrated by co-sedimentation with the 26S proteasome peak in glycerol density gradients after ATP-Mg2+ preincubation, and nin1-1 mutant cells accumulate polyubiquitinated proteins at restrictive temperatures, indicating a role in proteasome-dependent proteolysis. Glycerol density gradient fractionation, polyubiquitin accumulation assay, genetic analysis of cell cycle progression The EMBO journal High 7621825
1995 Loss of Nin1p function causes synthetic lethality with certain cdc28 alleles and failure to activate Cdc28p (Cdk1) histone H1 kinase activity after release from G1 or S-phase arrest, placing Nin1p/PSMD8 upstream of Cdc28p activation via proteasome-dependent proteolysis. Genetic epistasis (synthetic lethality screen), histone H1 kinase activity assay The EMBO journal Medium 7621825
2000 Fission yeast Mts3 (Rpn12/PSMD8 ortholog) physically binds Pus1 (Rpn10) in vitro, and the polyubiquitin-binding activity of Pus1 is essential for cell viability when Mts3 function is compromised (synthetic lethality of Δpus1 with mts3-1); overexpression of wild-type but not polyubiquitin-binding-deficient Pus1 rescues mts3-1, indicating functional cooperation between Rpn12 and Rpn10 in polyubiquitin substrate recognition. In vitro binding assay, genetic epistasis (synthetic lethality, overexpression rescue) The Journal of biological chemistry High 10809753
1999 Genetic epistasis in yeast demonstrates that rpn12-1 (nin1-1) is synthetically lethal with rpt1-2, a mutation in the ATPase subunit Rpt1, placing Rpn12 in a functionally interacting relationship with the Rpt1 ATPase of the 19S base subparticle. Synthetic lethality screen, double-mutant analysis Molecular & general genetics : MGG Medium 10503546
2010 S. pombe Rpn12 (PSMD8 ortholog) directly binds the UIM of Rpn10 in vitro with affinity comparable to Lys48-linked diubiquitin, as shown by NMR and crystallography, demonstrating that Rpn12 can compete with ubiquitin for Rpn10 UIM binding and thus potentially modulate Rpn10's activity as a proteasomal ubiquitin receptor. Crystal structure of Rpn10 vWA domain, NMR characterization of UIM–Rpn12 interaction, binding affinity measurement The Journal of biological chemistry High 20739285
2012 Crystal structure of Rpn12 (PSMD8 ortholog) reveals a PCI-domain fold; mutagenesis of residues at a surface site impairs Rpn12 binding to Rpn10 in vitro and reduces Rpn10 incorporation into proteasomes in vivo, identifying the structural basis for Rpn12-mediated recruitment of the ubiquitin receptor Rpn10 to the 19S lid. Crystal structure determination, site-directed mutagenesis, in vitro binding assay, in vivo proteasome subunit incorporation assay The Biochemical journal High 22906049
2020 In C. elegans, RPN-12 (PSMD8 ortholog) null mutants lack sperm (feminized germline) without major loss of proteasome proteolytic activity; this phenotype is suppressed by downregulation of TRA-1, placing RPN-12 in the hermaphrodite germline sex determination pathway; RPN-12 loss also causes nuclear accumulation of meiotic kinase WEE-1.3 that is not reproduced by chemical proteasome inhibition, indicating a proteasome-independent or non-catalytic role for this subunit in WEE-1.3 localization. Null mutant analysis (rpn-12(av93)), RNAi epistasis, proteasome activity assay, protein localization imaging Developmental dynamics Medium 32767462
2020 Backbone NMR resonance assignments of S. cerevisiae Rpn12 (PSMD8 ortholog) confirm it contains an N-terminal TPR-like domain and C-terminal WH domain, providing structural framework for understanding its interactions with other 19S subunits. NMR backbone resonance assignment Biomolecular NMR assignments Low 32072453
2025 Human PSMD8 directly interacts with and stabilizes SLC7A11 (a ferroptosis suppressor), negatively regulating ferroptosis but not apoptosis in bladder cancer cells; USP14 cooperates with PSMD8 to enhance SLC7A11 protein abundance; reduction of PSMD8 sensitizes bladder cancer cells to cisplatin. Co-immunoprecipitation (direct interaction), knockdown experiments with ferroptosis/apoptosis assays, protein stability assays iScience Medium 41403840

Source papers

Stage 0 corpus · 43 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2001 Solution conditions can promote formation of either amyloid protofilaments or mature fibrils from the HypF N-terminal domain. Protein science : a publication of the Protein Society 117 11714922
2002 HypF, a carbamoyl phosphate-converting enzyme involved in [NiFe] hydrogenase maturation. The Journal of biological chemistry 93 12377778
1995 Nin1p, a regulatory subunit of the 26S proteasome, is necessary for activation of Cdc28p kinase of Saccharomyces cerevisiae. The EMBO journal 89 7621825
2004 Monitoring the process of HypF fibrillization and liposome permeabilization by protofibrils. Journal of molecular biology 87 15111058
2000 Analysis of a gene encoding Rpn10 of the fission yeast proteasome reveals that the polyubiquitin-binding site of this subunit is essential when Rpn12/Mts3 activity is compromised. The Journal of biological chemistry 71 10809753
2005 Amyloid formation from HypF-N under conditions in which the protein is initially in its native state. Journal of molecular biology 65 15740744
2010 Structure of Rpn10 and its interactions with polyubiquitin chains and the proteasome subunit Rpn12. The Journal of biological chemistry 58 20739285
2004 Analysis of the transcarbamoylation-dehydration reaction catalyzed by the hydrogenase maturation proteins HypF and HypE. European journal of biochemistry 56 15291820
2002 Crystal structure and anion binding in the prokaryotic hydrogenase maturation factor HypF acylphosphatase-like domain. Journal of molecular biology 56 12206761
1996 Analysis of the hydA locus of Escherichia coli: two genes (hydN and hypF) involved in formate and hydrogen metabolism. Archives of microbiology 48 8661925
2008 Conformational properties of the aggregation precursor state of HypF-N. Journal of molecular biology 41 18466920
2006 Natively folded HypF-N and its early amyloid aggregates interact with phospholipid monolayers and destabilize supported phospholipid bilayers. Biophysical journal 38 16997875
2004 Patterns of cell death triggered in two different cell lines by HypF-N prefibrillar aggregates. FASEB journal : official publication of the Federation of American Societies for Experimental Biology 37 15604358
2012 Structural basis for the reaction mechanism of S-carbamoylation of HypE by HypF in the maturation of [NiFe]-hydrogenases. The Journal of biological chemistry 33 22740694
2013 Amyloid-β oligomer synaptotoxicity is mimicked by oligomers of the model protein HypF-N. Neurobiology of aging 30 23601807
2007 Structure of [NiFe] hydrogenase maturation protein HypE from Escherichia coli and its interaction with HypF. Journal of bacteriology 30 18065529
2011 Structure of hydrogenase maturation protein HypF with reaction intermediates shows two active sites. Structure (London, England : 1993) 28 22153500
2018 Structural differences between toxic and nontoxic HypF-N oligomers. Chemical communications (Cambridge, England) 27 30020284
1998 Rhodobacter capsulatus HypF is involved in regulation of hydrogenase synthesis through the HupUV proteins. European journal of biochemistry 26 9492269
2011 Downregulation of NIN/RPN12 binding protein inhibit the growth of human hepatocellular carcinoma cells. Molecular biology reports 23 21573803
2016 Interaction of toxic and non-toxic HypF-N oligomers with lipid bilayers investigated at high resolution with atomic force microscopy. Oncotarget 22 27391440
2012 Structural and functional characterization of Rpn12 identifies residues required for Rpn10 proteasome incorporation. The Biochemical journal 19 22906049
2012 Salt anions promote the conversion of HypF-N into amyloid-like oligomers and modulate the structure of the oligomers and the monomeric precursor state. Journal of molecular biology 19 23041425
2012 siRNA mediated silencing of NIN1/RPN12 binding protein 1 homolog inhibits proliferation and growth of breast cancer cells. Asian Pacific journal of cancer prevention : APJCP 16 22901129
2012 Glycosaminoglycans (GAGs) suppress the toxicity of HypF-N prefibrillar aggregates. Journal of molecular biology 15 22326346
2009 Conformational properties of unfolded HypF-N. The journal of physical chemistry. B 15 19928868
2020 Toxic oligomers of the amyloidogenic HypF-N protein form pores in mitochondrial membranes. Scientific reports 12 33082392
2012 Structure of the [NiFe]-hydrogenase maturation protein HypF from Thermococcus kodakarensis KOD1. Acta crystallographica. Section F, Structural biology and crystallization communications 10 23027738
2011 The induction of α-helical structure in partially unfolded HypF-N does not affect its aggregation propensity. Protein engineering, design & selection : PEDS 10 21518735
2006 Differing molecular mechanisms appear to underlie early toxicity of prefibrillar HypF-N aggregates to different cell types. The FEBS journal 10 16649997
2020 The Caenorhabditis elegans proteasome subunit RPN-12 is required for hermaphrodite germline sex determination and oocyte quality. Developmental dynamics : an official publication of the American Association of Anatomists 8 32767462
1999 Genetic evidence for interaction between components of the yeast 26S proteasome: combination of a mutation in RPN12 (a lid component gene) with mutations in RPT1 (an ATPase gene) causes synthetic lethality. Molecular & general genetics : MGG 8 10503546
1997 The sequences of hypF, hypC and hypD complete the hyp gene cluster required for hydrogenase activity in Bradyrhizobium japonicum. Gene 8 9358044
2018 Toxic HypF-N Oligomers Selectively Bind the Plasma Membrane to Impair Cell Adhesion Capability. Biophysical journal 7 29590593
2014 Evaluation of NIN/RPN12 binding protein inhibits proliferation and growth in human renal cancer cells. Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine 6 25420906
2017 Retracted: siRNA Mediated Silencing of NIN1/RPN12 Binding Protein 1 Homolog Inhibits Proliferation and Growth of Breast Cancer Cells. Asian Pacific journal of cancer prevention : APJCP 5 29127950
2002 Crystallization and preliminary X-ray characterization of the acylphosphatase-like domain from the Escherichia coli hydrogenase maturation factor HypF. Acta crystallographica. Section D, Biological crystallography 5 11856843
2013 Effect of osmolytes on the fibrillation of HypF-N. Biochimie 3 23911865
2024 Protein profile changes during priming explants to embryogenic response in Coffea canephora: identification of the RPN12 proteasome subunit involved in the protein degradation. PeerJ 2 39544425
2009 Proteomic analysis of cells exposed to prefibrillar aggregates of HypF-N. Biochimica et biophysica acta 2 19409514
2018 Backbone NMR assignments of HypF-N under conditions generating toxic and non-toxic oligomers. Biomolecular NMR assignments 1 29786756
2025 PSMD8 cooperates with USP14 to promote bladder cancer progression by inhibiting ferroptosis. iScience 0 41403840
2020 Backbone 1H, 13C and 15N resonance assignments of the proteasome lid subunit Rpn12 from Saccharomyces cerevisiae. Biomolecular NMR assignments 0 32072453

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