{"gene":"PSMC3","run_date":"2026-06-10T06:43:36","timeline":{"discoveries":[{"year":1997,"finding":"PSMC3/TBP-1 is a component of the 19S regulatory cap of the 26S proteasome, contains a heptad leucine zipper at the N-terminus and conserved ATPase/DNA-RNA helicase motifs, and localizes to the manchette of elongating rat spermatids, as well as cytoplasmic granular bodies, paraaxonemal mitochondria, and outer dense fibers of the spermatid tail.","method":"cDNA cloning, indirect immunofluorescence, immunogold electron microscopy, chromatofocusing fractionation, immunoblotting","journal":"Molecular reproduction and development","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by immunofluorescence and immunogold EM with biochemical fractionation, single lab","pmids":["9266764"],"is_preprint":false},{"year":1992,"finding":"The yeast homolog of PSMC3/TBP-1 (TBPY) encodes a protein with a leucine-zipper-like heptad repeat and helicase sequence motifs, suggesting capacity for self-dimerization or heterodimerization via the hydrophobic region.","method":"cDNA cloning, sequence analysis, secondary structure prediction","journal":"DNA and cell biology","confidence":"Low","confidence_rationale":"Tier 4 / Weak — computational/structural prediction only; dimerization not experimentally confirmed","pmids":["1388730"],"is_preprint":false},{"year":1997,"finding":"PSMC3 (TBP-1) maps to human chromosome 11p12-p13, with a probable processed pseudogene locus on chromosome 9p.","method":"Fluorescence in situ hybridization (chromosomal mapping)","journal":"Human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct chromosomal mapping by FISH, single lab","pmids":["9048938"],"is_preprint":false},{"year":1998,"finding":"Mouse PSMC3/TBP-1 protein is localized predominantly to the nuclei of spermatogonia and spermatocytes in the testis, and its mRNA is robustly expressed in testis with heterogeneous distribution across other tissues; it retains inhibitory activity on HIV Tat-mediated transactivation.","method":"Immunohistochemistry, in situ hybridization, RT-PCR, cDNA cloning","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by immunohistochemistry and in situ hybridization, single lab","pmids":["9714759"],"is_preprint":false},{"year":1997,"finding":"A novel TBP-1-interacting protein (TBPIP) was cloned; it physically interacts with PSMC3/TBP-1 and co-localizes with it in vivo. TBPIP enhances the inhibitory action of TBP-1 on HIV Tat-mediated transactivation in a synergistic manner.","method":"Yeast two-hybrid, co-immunoprecipitation, co-localization assay, in vitro transactivation assay","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid plus co-localization and functional transactivation assay, single lab","pmids":["9345291"],"is_preprint":false},{"year":2000,"finding":"Both Psmc3 and Psmc4 are essential for early embryogenesis; Psmc3-deficient mice die before implantation with defective blastocyst development, establishing a non-redundant, essential role for Psmc3 in vivo.","method":"Gene targeting (knockout mice), embryological phenotyping","journal":"Genomics","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean gene-targeted knockout with defined developmental phenotype; independently confirmed for both paralogs, single lab","pmids":["10945464"],"is_preprint":false},{"year":2007,"finding":"PSMC3/TBP-1 physically binds p14ARF and stabilizes it against proteasomal degradation; this requires an intact N-terminal 39 amino acids of ARF. In vitro, p14ARF can be degraded by the 20S proteasome in a ubiquitin-independent manner, and TBP-1 counteracts this degradation.","method":"Co-immunoprecipitation, in vitro 20S proteasome degradation assay, deletion mutagenesis, western blotting","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution assay combined with mutagenesis and co-IP; multiple orthogonal methods in one study","pmids":["17334400"],"is_preprint":false},{"year":2009,"finding":"PSMC3/TBP-1 directly binds androgen receptor (AR) and TBPIP (TBP-1-interacting protein) in vitro and in LNCaP cells. TBP-1 augments AR-mediated transcription additively with TBPIP, and both the ATPase domain and leucine zipper of TBP-1 are required for transcriptional enhancement. TBP-1 is transiently recruited to the proximal androgen response element (ARE) of the PSA gene promoter in a ligand-dependent manner.","method":"Yeast two-hybrid, co-immunoprecipitation, GST pulldown, transient transfection reporter assay, chromatin immunoprecipitation (ChIP), domain deletion mutagenesis","journal":"Endocrinology","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — multiple orthogonal methods (Co-IP, pulldown, ChIP, mutagenesis, reporter assay) in single lab","pmids":["19325002"],"is_preprint":false},{"year":2009,"finding":"During rat spermatid development, PSMC3 and RNF19a (a ubiquitin protein ligase) interact and co-localize in Golgi-derived proacrosomal vesicles, along the cytosolic side of acrosomal membranes and acroplaxome, at the acroplaxome marginal ring, and in the developing sperm head-tail coupling apparatus and tail, implicating the ubiquitin-proteasome system in acrosome biogenesis and spermatid head shaping.","method":"cDNA cloning, co-immunoprecipitation, indirect immunofluorescence, immunogold electron microscopy","journal":"Developmental dynamics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP and orthogonal direct localization by immunofluorescence and immunoEM, single lab","pmids":["19517565"],"is_preprint":false},{"year":2011,"finding":"Stable knock-down of PSMC3/TBP-1 in human fibroblasts increases cell proliferation, migration, and resistance to apoptosis. TBP-1 silencing causes activation of the Akt/PKB kinase, and TBP-1 is itself a downstream target of Akt/PKB; MDM2, a known Akt target, plays a major role in this regulatory loop, suggesting a negative feedback mechanism modulating TBP-1 levels in proliferating cells.","method":"shRNA knockdown, cell proliferation/migration/apoptosis assays, western blotting for Akt phosphorylation, co-immunoprecipitation","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional loss-of-function with defined cellular phenotypes and pathway placement, single lab","pmids":["21991300"],"is_preprint":false},{"year":2020,"finding":"A deep intronic homozygous variant in PSMC3 causes transcription of a cryptic exon, leading to impaired protein homeostasis with accumulation of ubiquitinated proteins (proteotoxic stress) in patient fibroblasts; the TCF11/Nrf1 transcriptional pathway for proteasome recovery after proteasomal inhibition is constitutively activated but cannot be further induced upon chemical proteasome inhibition. Zebrafish PSMC3 knockout reproduces inner ear development anomalies and cataracts, establishing an essential role for PSMC3/Rpt5 in inner ear, lens, and CNS development.","method":"Whole-genome sequencing, patient fibroblast functional assays (ubiquitin accumulation, proteasome activity), TCF11/Nrf1 pathway reporter assays, CRISPR zebrafish knockout with phenotypic analysis","journal":"EMBO molecular medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — patient-derived functional data, pathway analysis, and in vivo zebrafish model with defined phenotypes; replicated across human and animal models","pmids":["32500975"],"is_preprint":false},{"year":2022,"finding":"PSMC3 physically interacts with AGO2 in an RNA-independent manner via its N-terminal coiled-coil motif. PSMC3 promotes RNAi activity by stabilizing AGO2 at the post-translational level: depletion of PSMC3 increases AGO2 ubiquitination and turnover via the 26S proteasome, whereas PSMC3 facilitates the interaction between AGO2 and the deubiquitylase USP14, leading to USP14-mediated deubiquitination and stabilization of AGO2.","method":"Yeast two-hybrid screen, co-immunoprecipitation, immunofluorescence, truncation mutagenesis, RNAi/EGFP reporter assay, cycloheximide chase, ubiquitination assay, western blotting","journal":"Cellular & molecular biology letters","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — multiple orthogonal methods (Y2H, Co-IP, domain mapping, functional RNAi assay, ubiquitination assay), single lab","pmids":["36528617"],"is_preprint":false},{"year":2022,"finding":"PSMC3 forms a ternary complex with VCPIP1 (a deubiquitinating enzyme) and HBx (hepatitis B virus X protein). Purified His-tagged PSMC3 rescues HBx degradation induced by the 20S proteasome in vitro; VCPIP1 synergizes this stabilization in vivo, acting through a ubiquitin-independent pathway to stabilize HBx.","method":"74-DUB yeast two-hybrid screen, co-immunoprecipitation, in vitro proteasome degradation assay with purified proteins, ubiquitination site mutant plasmids, western blotting","journal":"Journal of virology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with purified PSMC3 plus Y2H and Co-IP; multiple orthogonal methods, single lab","pmids":["35695579"],"is_preprint":false},{"year":2023,"finding":"De novo missense variants in PSMC3 (encoding the AAA-ATPase proteasome subunit Rpt5) disrupt substrate translocation by the 26S proteasome, inducing proteotoxic stress and alterations in proteins controlling developmental and innate immune programs. PSMC3 variants in patient T cells activate a type I interferon (IFN) response mediated by the intracellular stress sensor PKR, which could be blocked by PKR inhibition. Expression of PSMC3 variants in mouse neuronal cultures alters dendrite development; deletion of the PSMC3 Drosophila ortholog Rpt5 impairs reversal learning.","method":"Patient variant analysis, structural modeling, proteomic and transcriptomic analyses of patient T cells, mouse neuronal culture dendrite morphology assay, Drosophila Rpt5 knockout behavioral assay, PKR inhibitor rescue experiment","journal":"Science translational medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal in vitro and in vivo experimental systems (human T cells, mouse neurons, Drosophila), structural modeling, and pharmacological rescue all convergently supporting mechanism","pmids":["37256937"],"is_preprint":false},{"year":2024,"finding":"PSMC3 mediates ubiquitin-dependent proteasomal degradation of NRF2 in glioblastoma cells. The small molecule procyanidin B1 binds NRF2 and promotes the interaction between PSMC3 and NRF2, facilitating ubiquitin-dependent NRF2 degradation and inducing ferroptosis through H₂O₂ accumulation.","method":"Protein-small molecule docking, surface plasmon resonance, laser confocal z-stack assay, co-immunoprecipitation, mass spectrometry, western blotting, intracranial GBM orthotopic mouse model","journal":"Phytotherapy research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus SPR for binding and in vivo tumor model, but single lab and mechanism relies partly on docking","pmids":["39293861"],"is_preprint":false}],"current_model":"PSMC3 (TBP-1/Rpt5) is an AAA-ATPase component of the 19S regulatory cap of the 26S proteasome that uses its ATPase and leucine-zipper domains to unfold and translocate ubiquitinated substrates for degradation; beyond canonical proteasome function, it directly stabilizes p14ARF and AGO2 against ubiquitin-dependent degradation (the latter via facilitating USP14-mediated deubiquitination), acts as a transcriptional co-activator of nuclear receptors including androgen receptor, is essential for early embryogenesis and inner ear/lens development in vivo, and its dysfunction induces proteotoxic stress that activates a PKR-dependent type I interferon response linked to neurodevelopmental pathology."},"narrative":{"mechanistic_narrative":"PSMC3 (TBP-1/Rpt5) is an AAA-ATPase subunit of the 19S regulatory cap of the 26S proteasome, harboring an N-terminal heptad leucine zipper and conserved ATPase motifs, and its substrate-translocation function is essential for protein homeostasis and mammalian development [PMID:9266764, PMID:10945464]. Genetic ablation of Psmc3 causes pre-implantation embryonic lethality with defective blastocyst development, and PSMC3 loss in zebrafish reproduces inner ear and lens (cataract) anomalies, establishing a non-redundant requirement in early embryogenesis and sensory/CNS organogenesis [PMID:10945464, PMID:32500975]. Beyond bulk degradation, PSMC3 acts as a positive regulator of selected substrates: it directly binds and stabilizes the tumor suppressor p14ARF against ubiquitin-independent 20S degradation through ARF's N-terminal residues [PMID:17334400], and it stabilizes AGO2 by binding it RNA-independently via its N-terminal coiled-coil and recruiting the deubiquitylase USP14 to reverse AGO2 ubiquitination, thereby promoting RNAi activity [PMID:36528617]. PSMC3 also functions as a transcriptional co-activator of the androgen receptor, where both its ATPase domain and leucine zipper are required and it is recruited ligand-dependently to the PSA promoter ARE together with the partner TBPIP [PMID:9345291, PMID:19325002]. Disease-associated PSMC3 variants impair 26S substrate translocation and trigger proteotoxic stress: a deep intronic variant constitutively activates the TCF11/Nrf1 proteasome-recovery pathway in patient fibroblasts [PMID:32500975], and de novo missense variants drive a PKR-dependent type I interferon response and alter neuronal dendrite development and learning, linking PSMC3 dysfunction to neurodevelopmental pathology [PMID:37256937].","teleology":[{"year":1997,"claim":"Establishing PSMC3/TBP-1 as a 19S proteasome cap subunit with defined sequence architecture answered what class of molecule it is and where it acts in the cell.","evidence":"cDNA cloning, immunofluorescence and immunogold EM with biochemical fractionation in rat spermatids; FISH chromosomal mapping","pmids":["9266764","9048938"],"confidence":"Medium","gaps":["ATPase/helicase motifs identified by sequence but enzymatic activity not directly assayed","functional contribution of the leucine zipper untested"]},{"year":1998,"claim":"Tissue and subcellular localization plus retention of HIV Tat-transactivation inhibition placed PSMC3 in germ-cell nuclei and hinted at a transcription-modulating activity beyond degradation.","evidence":"Immunohistochemistry, in situ hybridization, RT-PCR in mouse testis with Tat transactivation assay","pmids":["9714759"],"confidence":"Medium","gaps":["mechanism of Tat inhibition not resolved","relationship between nuclear localization and proteasome function unclear"]},{"year":1997,"claim":"Identification of TBPIP as a direct PSMC3 partner that synergizes Tat inhibition provided the first physical interactor and a functional readout.","evidence":"Yeast two-hybrid, co-immunoprecipitation, co-localization, in vitro transactivation assay","pmids":["9345291"],"confidence":"Medium","gaps":["interaction interface not mapped","physiological context of TBPIP synergy beyond Tat unknown"]},{"year":2000,"claim":"Knockout established that PSMC3 is non-redundantly essential in vivo, ruling out functional compensation by paralogs during early development.","evidence":"Gene-targeted Psmc3 knockout mice with embryological phenotyping","pmids":["10945464"],"confidence":"High","gaps":["does not separate proteasome-dependent from proteasome-independent roles in the lethal phenotype","cell-type-specific requirements not addressed"]},{"year":2007,"claim":"Demonstrating that PSMC3 binds and protects p14ARF from 20S degradation revealed a substrate-stabilizing function opposite to canonical proteolysis.","evidence":"Co-IP, in vitro 20S degradation assay, deletion mutagenesis","pmids":["17334400"],"confidence":"High","gaps":["how a proteasome subunit shields rather than feeds a substrate is mechanistically unresolved","in vivo consequences for ARF tumor-suppressor signaling not established"]},{"year":2009,"claim":"Identifying PSMC3 as a domain-dependent AR co-activator recruited to AREs defined a direct transcriptional role for the subunit at hormone-responsive promoters.","evidence":"Y2H, Co-IP, GST pulldown, reporter assay, ChIP, domain deletion in LNCaP cells","pmids":["19325002"],"confidence":"High","gaps":["whether co-activation requires assembled proteasome or free PSMC3 unknown","genome-wide AR target scope not mapped"]},{"year":2009,"claim":"Co-localization and interaction with the ligase RNF19a connected PSMC3 to ubiquitin-proteasome activity during acrosome biogenesis and spermatid head shaping.","evidence":"Co-IP, immunofluorescence, immunogold EM in rat spermatids","pmids":["19517565"],"confidence":"Medium","gaps":["functional requirement of PSMC3 in spermiogenesis not tested by loss-of-function","substrates at the acroplaxome unidentified"]},{"year":2011,"claim":"Placing PSMC3 in an Akt/MDM2 feedback loop linked its levels to proliferation, migration, and apoptosis control in fibroblasts.","evidence":"shRNA knockdown, proliferation/migration/apoptosis assays, Akt phosphorylation immunoblotting, Co-IP","pmids":["21991300"],"confidence":"Medium","gaps":["direct vs indirect regulation of PSMC3 by Akt not fully resolved","phenotypes not validated in non-fibroblast systems"]},{"year":2020,"claim":"A pathogenic deep intronic variant tied PSMC3 dysfunction to proteotoxic stress and constitutive TCF11/Nrf1 activation, and zebrafish knockout defined inner ear, lens, and CNS developmental requirements.","evidence":"Whole-genome sequencing, patient fibroblast proteasome/ubiquitin assays, Nrf1 reporter assays, CRISPR zebrafish knockout","pmids":["32500975"],"confidence":"High","gaps":["how loss of proteasome capacity yields tissue-specific developmental defects unclear","link between TCF11/Nrf1 activation and phenotype not directly tested"]},{"year":2022,"claim":"Demonstrating PSMC3-dependent stabilization of AGO2 via USP14 recruitment, and of HBx via VCPIP1, generalized PSMC3's role as a recruiter of deubiquitylases that rescue substrates from degradation.","evidence":"Y2H screens, Co-IP, domain mapping, in vitro 20S degradation with purified PSMC3, RNAi reporter, ubiquitination and cycloheximide-chase assays","pmids":["36528617","35695579"],"confidence":"High","gaps":["whether DUB recruitment occurs in the context of the assembled proteasome unknown","selectivity rules for which substrates PSMC3 stabilizes vs degrades undefined"]},{"year":2023,"claim":"Showing that de novo missense variants impair substrate translocation and trigger PKR-dependent type I interferon plus neuronal phenotypes established a causal mechanism linking proteasome dysfunction to neurodevelopmental disease.","evidence":"Patient variant analysis, structural modeling, proteomics/transcriptomics of patient T cells, mouse neuronal dendrite assays, Drosophila Rpt5 behavioral assay, PKR inhibitor rescue","pmids":["37256937"],"confidence":"High","gaps":["upstream trigger sensed by PKR not molecularly defined","translatability of PKR inhibition to patient neurodevelopment untested"]},{"year":2024,"claim":"Identifying PSMC3-mediated ubiquitin-dependent NRF2 degradation, promotable by procyanidin B1, added a context where PSMC3 drives substrate turnover and ferroptosis in glioblastoma.","evidence":"Docking, SPR, Co-IP, mass spectrometry, orthotopic GBM mouse model","pmids":["39293861"],"confidence":"Medium","gaps":["mechanism partly reliant on docking","specificity of PSMC3 for NRF2 vs general proteasome activity not isolated"]},{"year":null,"claim":"It remains unresolved what molecular determinants dictate whether PSMC3 routes a given substrate toward stabilization (via DUB recruitment) versus degradation, and how this switch is regulated across tissues.","evidence":"","pmids":[],"confidence":"Medium","gaps":["no unifying model for substrate-fate selection","structural basis of PSMC3-DUB-substrate ternary complexes unknown","in vivo balance of these activities uncharacterized"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[0,13]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[6,11,14]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[7]},{"term_id":"GO:0140313","term_label":"molecular sequestering activity","supporting_discovery_ids":[6,11,12]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[3]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[0,6,11]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[5,10]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[13]}],"complexes":["26S proteasome 19S regulatory cap"],"partners":["TBPIP","AR","AGO2","USP14","VCPIP1","HBX","RNF19A","NFE2L2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P17980","full_name":"26S proteasome regulatory subunit 6A","aliases":["26S proteasome AAA-ATPase subunit RPT5","Proteasome 26S subunit ATPase 3","Proteasome subunit P50","Tat-binding protein 1","TBP-1"],"length_aa":439,"mass_kda":49.2,"function":"Component of the 26S proteasome, a multiprotein complex involved in the ATP-dependent degradation of ubiquitinated proteins. This complex plays a key role in the maintenance of protein homeostasis by removing misfolded or damaged proteins, which could impair cellular functions, and by removing proteins whose functions are no longer required. Therefore, the proteasome participates in numerous cellular processes, including cell cycle progression, apoptosis, or DNA damage repair. PSMC3 belongs to the heterohexameric ring of AAA (ATPases associated with diverse cellular activities) proteins that unfolds ubiquitinated target proteins that are concurrently translocated into a proteolytic chamber and degraded into peptides","subcellular_location":"Cytoplasm; Nucleus","url":"https://www.uniprot.org/uniprotkb/P17980/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/PSMC3","classification":"Common 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POLYNEUROPATHY; DCIDP","url":"https://www.omim.org/entry/619354"},{"mim_id":"614324","title":"OVARIAN DYSGENESIS 3; ODG3","url":"https://www.omim.org/entry/614324"},{"mim_id":"611176","title":"JNK/MAPK8-ASSOCIATED MEMBRANE PROTEIN; JKAMP","url":"https://www.omim.org/entry/611176"},{"mim_id":"608665","title":"PSMC3-INTERACTING PROTEIN; PSMC3IP","url":"https://www.omim.org/entry/608665"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Cytosol","reliability":"Approved"},{"location":"Nuclear bodies","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PSMC3"},"hgnc":{"alias_symbol":["TBP1","TBP-1","RPT5"],"prev_symbol":[]},"alphafold":{"accession":"P17980","domains":[{"cath_id":"2.40.50.140","chopping":"86-101_117-162","consensus_level":"high","plddt":81.879,"start":86,"end":162},{"cath_id":"3.40.50.300","chopping":"171-352","consensus_level":"high","plddt":82.9915,"start":171,"end":352},{"cath_id":"1.10.8.60","chopping":"358-432","consensus_level":"high","plddt":89.1784,"start":358,"end":432},{"cath_id":"1.20.5","chopping":"24-80","consensus_level":"high","plddt":83.0104,"start":24,"end":80}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P17980","model_url":"https://alphafold.ebi.ac.uk/files/AF-P17980-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P17980-F1-predicted_aligned_error_v6.png","plddt_mean":80.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PSMC3","jax_strain_url":"https://www.jax.org/strain/search?query=PSMC3"},"sequence":{"accession":"P17980","fasta_url":"https://rest.uniprot.org/uniprotkb/P17980.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P17980/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P17980"}},"corpus_meta":[{"pmid":"15779989","id":"PMC_15779989","title":"Specificity 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dimerization not experimentally confirmed\",\n      \"pmids\": [\"1388730\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"PSMC3 (TBP-1) maps to human chromosome 11p12-p13, with a probable processed pseudogene locus on chromosome 9p.\",\n      \"method\": \"Fluorescence in situ hybridization (chromosomal mapping)\",\n      \"journal\": \"Human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct chromosomal mapping by FISH, single lab\",\n      \"pmids\": [\"9048938\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Mouse PSMC3/TBP-1 protein is localized predominantly to the nuclei of spermatogonia and spermatocytes in the testis, and its mRNA is robustly expressed in testis with heterogeneous distribution across other tissues; it retains inhibitory activity on HIV Tat-mediated transactivation.\",\n      \"method\": \"Immunohistochemistry, in situ hybridization, RT-PCR, cDNA cloning\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization by immunohistochemistry and in situ hybridization, single lab\",\n      \"pmids\": [\"9714759\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"A novel TBP-1-interacting protein (TBPIP) was cloned; it physically interacts with PSMC3/TBP-1 and co-localizes with it in vivo. TBPIP enhances the inhibitory action of TBP-1 on HIV Tat-mediated transactivation in a synergistic manner.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, co-localization assay, in vitro transactivation assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid plus co-localization and functional transactivation assay, single lab\",\n      \"pmids\": [\"9345291\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Both Psmc3 and Psmc4 are essential for early embryogenesis; Psmc3-deficient mice die before implantation with defective blastocyst development, establishing a non-redundant, essential role for Psmc3 in vivo.\",\n      \"method\": \"Gene targeting (knockout mice), embryological phenotyping\",\n      \"journal\": \"Genomics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean gene-targeted knockout with defined developmental phenotype; independently confirmed for both paralogs, single lab\",\n      \"pmids\": [\"10945464\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"PSMC3/TBP-1 physically binds p14ARF and stabilizes it against proteasomal degradation; this requires an intact N-terminal 39 amino acids of ARF. In vitro, p14ARF can be degraded by the 20S proteasome in a ubiquitin-independent manner, and TBP-1 counteracts this degradation.\",\n      \"method\": \"Co-immunoprecipitation, in vitro 20S proteasome degradation assay, deletion mutagenesis, western blotting\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution assay combined with mutagenesis and co-IP; multiple orthogonal methods in one study\",\n      \"pmids\": [\"17334400\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"PSMC3/TBP-1 directly binds androgen receptor (AR) and TBPIP (TBP-1-interacting protein) in vitro and in LNCaP cells. TBP-1 augments AR-mediated transcription additively with TBPIP, and both the ATPase domain and leucine zipper of TBP-1 are required for transcriptional enhancement. TBP-1 is transiently recruited to the proximal androgen response element (ARE) of the PSA gene promoter in a ligand-dependent manner.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, GST pulldown, transient transfection reporter assay, chromatin immunoprecipitation (ChIP), domain deletion mutagenesis\",\n      \"journal\": \"Endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — multiple orthogonal methods (Co-IP, pulldown, ChIP, mutagenesis, reporter assay) in single lab\",\n      \"pmids\": [\"19325002\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"During rat spermatid development, PSMC3 and RNF19a (a ubiquitin protein ligase) interact and co-localize in Golgi-derived proacrosomal vesicles, along the cytosolic side of acrosomal membranes and acroplaxome, at the acroplaxome marginal ring, and in the developing sperm head-tail coupling apparatus and tail, implicating the ubiquitin-proteasome system in acrosome biogenesis and spermatid head shaping.\",\n      \"method\": \"cDNA cloning, co-immunoprecipitation, indirect immunofluorescence, immunogold electron microscopy\",\n      \"journal\": \"Developmental dynamics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP and orthogonal direct localization by immunofluorescence and immunoEM, single lab\",\n      \"pmids\": [\"19517565\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Stable knock-down of PSMC3/TBP-1 in human fibroblasts increases cell proliferation, migration, and resistance to apoptosis. TBP-1 silencing causes activation of the Akt/PKB kinase, and TBP-1 is itself a downstream target of Akt/PKB; MDM2, a known Akt target, plays a major role in this regulatory loop, suggesting a negative feedback mechanism modulating TBP-1 levels in proliferating cells.\",\n      \"method\": \"shRNA knockdown, cell proliferation/migration/apoptosis assays, western blotting for Akt phosphorylation, co-immunoprecipitation\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional loss-of-function with defined cellular phenotypes and pathway placement, single lab\",\n      \"pmids\": [\"21991300\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"A deep intronic homozygous variant in PSMC3 causes transcription of a cryptic exon, leading to impaired protein homeostasis with accumulation of ubiquitinated proteins (proteotoxic stress) in patient fibroblasts; the TCF11/Nrf1 transcriptional pathway for proteasome recovery after proteasomal inhibition is constitutively activated but cannot be further induced upon chemical proteasome inhibition. Zebrafish PSMC3 knockout reproduces inner ear development anomalies and cataracts, establishing an essential role for PSMC3/Rpt5 in inner ear, lens, and CNS development.\",\n      \"method\": \"Whole-genome sequencing, patient fibroblast functional assays (ubiquitin accumulation, proteasome activity), TCF11/Nrf1 pathway reporter assays, CRISPR zebrafish knockout with phenotypic analysis\",\n      \"journal\": \"EMBO molecular medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — patient-derived functional data, pathway analysis, and in vivo zebrafish model with defined phenotypes; replicated across human and animal models\",\n      \"pmids\": [\"32500975\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"PSMC3 physically interacts with AGO2 in an RNA-independent manner via its N-terminal coiled-coil motif. PSMC3 promotes RNAi activity by stabilizing AGO2 at the post-translational level: depletion of PSMC3 increases AGO2 ubiquitination and turnover via the 26S proteasome, whereas PSMC3 facilitates the interaction between AGO2 and the deubiquitylase USP14, leading to USP14-mediated deubiquitination and stabilization of AGO2.\",\n      \"method\": \"Yeast two-hybrid screen, co-immunoprecipitation, immunofluorescence, truncation mutagenesis, RNAi/EGFP reporter assay, cycloheximide chase, ubiquitination assay, western blotting\",\n      \"journal\": \"Cellular & molecular biology letters\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — multiple orthogonal methods (Y2H, Co-IP, domain mapping, functional RNAi assay, ubiquitination assay), single lab\",\n      \"pmids\": [\"36528617\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"PSMC3 forms a ternary complex with VCPIP1 (a deubiquitinating enzyme) and HBx (hepatitis B virus X protein). Purified His-tagged PSMC3 rescues HBx degradation induced by the 20S proteasome in vitro; VCPIP1 synergizes this stabilization in vivo, acting through a ubiquitin-independent pathway to stabilize HBx.\",\n      \"method\": \"74-DUB yeast two-hybrid screen, co-immunoprecipitation, in vitro proteasome degradation assay with purified proteins, ubiquitination site mutant plasmids, western blotting\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with purified PSMC3 plus Y2H and Co-IP; multiple orthogonal methods, single lab\",\n      \"pmids\": [\"35695579\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"De novo missense variants in PSMC3 (encoding the AAA-ATPase proteasome subunit Rpt5) disrupt substrate translocation by the 26S proteasome, inducing proteotoxic stress and alterations in proteins controlling developmental and innate immune programs. PSMC3 variants in patient T cells activate a type I interferon (IFN) response mediated by the intracellular stress sensor PKR, which could be blocked by PKR inhibition. Expression of PSMC3 variants in mouse neuronal cultures alters dendrite development; deletion of the PSMC3 Drosophila ortholog Rpt5 impairs reversal learning.\",\n      \"method\": \"Patient variant analysis, structural modeling, proteomic and transcriptomic analyses of patient T cells, mouse neuronal culture dendrite morphology assay, Drosophila Rpt5 knockout behavioral assay, PKR inhibitor rescue experiment\",\n      \"journal\": \"Science translational medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal in vitro and in vivo experimental systems (human T cells, mouse neurons, Drosophila), structural modeling, and pharmacological rescue all convergently supporting mechanism\",\n      \"pmids\": [\"37256937\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"PSMC3 mediates ubiquitin-dependent proteasomal degradation of NRF2 in glioblastoma cells. The small molecule procyanidin B1 binds NRF2 and promotes the interaction between PSMC3 and NRF2, facilitating ubiquitin-dependent NRF2 degradation and inducing ferroptosis through H₂O₂ accumulation.\",\n      \"method\": \"Protein-small molecule docking, surface plasmon resonance, laser confocal z-stack assay, co-immunoprecipitation, mass spectrometry, western blotting, intracranial GBM orthotopic mouse model\",\n      \"journal\": \"Phytotherapy research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus SPR for binding and in vivo tumor model, but single lab and mechanism relies partly on docking\",\n      \"pmids\": [\"39293861\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PSMC3 (TBP-1/Rpt5) is an AAA-ATPase component of the 19S regulatory cap of the 26S proteasome that uses its ATPase and leucine-zipper domains to unfold and translocate ubiquitinated substrates for degradation; beyond canonical proteasome function, it directly stabilizes p14ARF and AGO2 against ubiquitin-dependent degradation (the latter via facilitating USP14-mediated deubiquitination), acts as a transcriptional co-activator of nuclear receptors including androgen receptor, is essential for early embryogenesis and inner ear/lens development in vivo, and its dysfunction induces proteotoxic stress that activates a PKR-dependent type I interferon response linked to neurodevelopmental pathology.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PSMC3 (TBP-1/Rpt5) is an AAA-ATPase subunit of the 19S regulatory cap of the 26S proteasome, harboring an N-terminal heptad leucine zipper and conserved ATPase motifs, and its substrate-translocation function is essential for protein homeostasis and mammalian development [#0, #5]. Genetic ablation of Psmc3 causes pre-implantation embryonic lethality with defective blastocyst development, and PSMC3 loss in zebrafish reproduces inner ear and lens (cataract) anomalies, establishing a non-redundant requirement in early embryogenesis and sensory/CNS organogenesis [#5, #10]. Beyond bulk degradation, PSMC3 acts as a positive regulator of selected substrates: it directly binds and stabilizes the tumor suppressor p14ARF against ubiquitin-independent 20S degradation through ARF's N-terminal residues [#6], and it stabilizes AGO2 by binding it RNA-independently via its N-terminal coiled-coil and recruiting the deubiquitylase USP14 to reverse AGO2 ubiquitination, thereby promoting RNAi activity [#11]. PSMC3 also functions as a transcriptional co-activator of the androgen receptor, where both its ATPase domain and leucine zipper are required and it is recruited ligand-dependently to the PSA promoter ARE together with the partner TBPIP [#4, #7]. Disease-associated PSMC3 variants impair 26S substrate translocation and trigger proteotoxic stress: a deep intronic variant constitutively activates the TCF11/Nrf1 proteasome-recovery pathway in patient fibroblasts [#10], and de novo missense variants drive a PKR-dependent type I interferon response and alter neuronal dendrite development and learning, linking PSMC3 dysfunction to neurodevelopmental pathology [#13].\",\n  \"teleology\": [\n    {\n      \"year\": 1997,\n      \"claim\": \"Establishing PSMC3/TBP-1 as a 19S proteasome cap subunit with defined sequence architecture answered what class of molecule it is and where it acts in the cell.\",\n      \"evidence\": \"cDNA cloning, immunofluorescence and immunogold EM with biochemical fractionation in rat spermatids; FISH chromosomal mapping\",\n      \"pmids\": [\"9266764\", \"9048938\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"ATPase/helicase motifs identified by sequence but enzymatic activity not directly assayed\", \"functional contribution of the leucine zipper untested\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Tissue and subcellular localization plus retention of HIV Tat-transactivation inhibition placed PSMC3 in germ-cell nuclei and hinted at a transcription-modulating activity beyond degradation.\",\n      \"evidence\": \"Immunohistochemistry, in situ hybridization, RT-PCR in mouse testis with Tat transactivation assay\",\n      \"pmids\": [\"9714759\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"mechanism of Tat inhibition not resolved\", \"relationship between nuclear localization and proteasome function unclear\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Identification of TBPIP as a direct PSMC3 partner that synergizes Tat inhibition provided the first physical interactor and a functional readout.\",\n      \"evidence\": \"Yeast two-hybrid, co-immunoprecipitation, co-localization, in vitro transactivation assay\",\n      \"pmids\": [\"9345291\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"interaction interface not mapped\", \"physiological context of TBPIP synergy beyond Tat unknown\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Knockout established that PSMC3 is non-redundantly essential in vivo, ruling out functional compensation by paralogs during early development.\",\n      \"evidence\": \"Gene-targeted Psmc3 knockout mice with embryological phenotyping\",\n      \"pmids\": [\"10945464\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"does not separate proteasome-dependent from proteasome-independent roles in the lethal phenotype\", \"cell-type-specific requirements not addressed\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Demonstrating that PSMC3 binds and protects p14ARF from 20S degradation revealed a substrate-stabilizing function opposite to canonical proteolysis.\",\n      \"evidence\": \"Co-IP, in vitro 20S degradation assay, deletion mutagenesis\",\n      \"pmids\": [\"17334400\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"how a proteasome subunit shields rather than feeds a substrate is mechanistically unresolved\", \"in vivo consequences for ARF tumor-suppressor signaling not established\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Identifying PSMC3 as a domain-dependent AR co-activator recruited to AREs defined a direct transcriptional role for the subunit at hormone-responsive promoters.\",\n      \"evidence\": \"Y2H, Co-IP, GST pulldown, reporter assay, ChIP, domain deletion in LNCaP cells\",\n      \"pmids\": [\"19325002\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"whether co-activation requires assembled proteasome or free PSMC3 unknown\", \"genome-wide AR target scope not mapped\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Co-localization and interaction with the ligase RNF19a connected PSMC3 to ubiquitin-proteasome activity during acrosome biogenesis and spermatid head shaping.\",\n      \"evidence\": \"Co-IP, immunofluorescence, immunogold EM in rat spermatids\",\n      \"pmids\": [\"19517565\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"functional requirement of PSMC3 in spermiogenesis not tested by loss-of-function\", \"substrates at the acroplaxome unidentified\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Placing PSMC3 in an Akt/MDM2 feedback loop linked its levels to proliferation, migration, and apoptosis control in fibroblasts.\",\n      \"evidence\": \"shRNA knockdown, proliferation/migration/apoptosis assays, Akt phosphorylation immunoblotting, Co-IP\",\n      \"pmids\": [\"21991300\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"direct vs indirect regulation of PSMC3 by Akt not fully resolved\", \"phenotypes not validated in non-fibroblast systems\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"A pathogenic deep intronic variant tied PSMC3 dysfunction to proteotoxic stress and constitutive TCF11/Nrf1 activation, and zebrafish knockout defined inner ear, lens, and CNS developmental requirements.\",\n      \"evidence\": \"Whole-genome sequencing, patient fibroblast proteasome/ubiquitin assays, Nrf1 reporter assays, CRISPR zebrafish knockout\",\n      \"pmids\": [\"32500975\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"how loss of proteasome capacity yields tissue-specific developmental defects unclear\", \"link between TCF11/Nrf1 activation and phenotype not directly tested\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrating PSMC3-dependent stabilization of AGO2 via USP14 recruitment, and of HBx via VCPIP1, generalized PSMC3's role as a recruiter of deubiquitylases that rescue substrates from degradation.\",\n      \"evidence\": \"Y2H screens, Co-IP, domain mapping, in vitro 20S degradation with purified PSMC3, RNAi reporter, ubiquitination and cycloheximide-chase assays\",\n      \"pmids\": [\"36528617\", \"35695579\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"whether DUB recruitment occurs in the context of the assembled proteasome unknown\", \"selectivity rules for which substrates PSMC3 stabilizes vs degrades undefined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Showing that de novo missense variants impair substrate translocation and trigger PKR-dependent type I interferon plus neuronal phenotypes established a causal mechanism linking proteasome dysfunction to neurodevelopmental disease.\",\n      \"evidence\": \"Patient variant analysis, structural modeling, proteomics/transcriptomics of patient T cells, mouse neuronal dendrite assays, Drosophila Rpt5 behavioral assay, PKR inhibitor rescue\",\n      \"pmids\": [\"37256937\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"upstream trigger sensed by PKR not molecularly defined\", \"translatability of PKR inhibition to patient neurodevelopment untested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identifying PSMC3-mediated ubiquitin-dependent NRF2 degradation, promotable by procyanidin B1, added a context where PSMC3 drives substrate turnover and ferroptosis in glioblastoma.\",\n      \"evidence\": \"Docking, SPR, Co-IP, mass spectrometry, orthotopic GBM mouse model\",\n      \"pmids\": [\"39293861\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"mechanism partly reliant on docking\", \"specificity of PSMC3 for NRF2 vs general proteasome activity not isolated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved what molecular determinants dictate whether PSMC3 routes a given substrate toward stabilization (via DUB recruitment) versus degradation, and how this switch is regulated across tissues.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"no unifying model for substrate-fate selection\", \"structural basis of PSMC3-DUB-substrate ternary complexes unknown\", \"in vivo balance of these activities uncharacterized\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [0, 13]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [6, 11, 14]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"GO:0140313\", \"supporting_discovery_ids\": [6, 11, 12]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 6, 11]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [5, 10]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [13]}\n    ],\n    \"complexes\": [\"26S proteasome 19S regulatory cap\"],\n    \"partners\": [\"TBPIP\", \"AR\", \"AGO2\", \"USP14\", \"VCPIP1\", \"HBx\", \"RNF19A\", \"NFE2L2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}