{"gene":"PSME3IP1","run_date":"2026-06-10T06:43:36","timeline":{"discoveries":[{"year":2018,"finding":"PIP30/FAM192A (PSME3IP1) directly binds PA28γ (REGγ) via its C-terminal end, and this interaction is stabilized by casein kinase 2 (CK2) phosphorylation of PIP30. PIP30 binds to both free and 20S proteasome-associated PA28γ, increases PA28γ association with the 20S proteasome in cells, alters PA28γ-dependent peptide degradation by the 20S proteasome in vitro, and negatively controls PA28γ localization to Cajal bodies by inhibiting its association with coilin.","method":"Direct binding assays, co-immunoprecipitation, in vitro peptide degradation assay, phosphorylation assays with CK2, fluorescence microscopy for Cajal body localization","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — multiple orthogonal methods including direct binding assays, in vitro functional assay, co-IP, and cellular localization experiments in a single focused study","pmids":["29934401"],"is_preprint":false},{"year":2020,"finding":"NIP30 (PSME3IP1) acts as an inhibitor of the REGγ-proteasome by binding to REGγ via an evolutionarily conserved serine-rich domain that undergoes 4-serine phosphorylation. CDC25A phosphatase regulates NIP30 phosphorylation status, and phosphorylated NIP30 modulates REGγ activity during the cell cycle and after DNA damage, controlling REGγ-mediated degradation of the target protein p21 in vivo.","method":"Co-immunoprecipitation, site-directed mutagenesis of serine residues, phosphomimetic/phosphodead mutant assays, in vivo validation using p53-/- and p53/REGγ double-knockout mice, cell proliferation and chemosensitivity assays","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal co-IP, mutagenesis of phosphorylation sites, in vivo genetic rescue with double-KO mice, multiple orthogonal methods","pmids":["32764536"],"is_preprint":false},{"year":2022,"finding":"Human FAM192A (PSME3IP1) functions as a step II spliceosomal factor during exon ligation: cryo-EM structures of pre-C*-I and pre-C*-II spliceosomal complexes show FAM192A contacts the duplex between U2 snRNA and the branch site in both intermediate complexes.","method":"Cryo-EM structural analysis of human spliceosomal complexes at 3.6 Å resolution","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Moderate — high-resolution cryo-EM structure with defined molecular contacts, single study but structural tier 1 method","pmids":["35705093"],"is_preprint":false},{"year":2023,"finding":"Fyv6, the yeast homolog of human FAM192A (PSME3IP1), functions as a second-step splicing factor: deletion of FYV6 causes genetic interactions with essential splicing factors Prp8, Prp16, and Prp22, accumulation of first-step splicing products in vitro, impaired exon ligation, and altered 3' splice site selection in vivo.","method":"Genetic deletion, in vivo reporter splicing assays, in vitro splicing assay with whole-cell extracts, genetic interaction analysis","journal":"RNA (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 2 / Strong — biochemical in vitro splicing assays combined with multiple genetic epistasis experiments and in vivo reporter assays; published peer-reviewed study","pmids":["37625852"],"is_preprint":false},{"year":2024,"finding":"Fyv6 (yeast homolog of FAM192A/PSME3IP1) is the only second-step spliceosomal factor that contacts the Prp22 ATPase, and its binding is mutually exclusive with that of the first-step factor Yju2. Loss of Fyv6 activates non-consensus, branch point-proximal 3' splice sites transcriptome-wide, and structure-guided domain dissection identified functional domains required for these activities.","method":"Cryo-EM structure of yeast product complex spliceosome at 2.3 Å, RNA-seq transcriptome analysis, genetic suppressor screen, structure-guided mutagenesis","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 / Strong — high-resolution cryo-EM structure combined with transcriptomics, genetics, and mutagenesis in a single integrated study","pmids":["39688371"],"is_preprint":false},{"year":2024,"finding":"NIP30 (PSME3IP1) participates in a NIP30/REGγ/TRAF6 regulatory axis in osteoclasts: dephosphorylation of NIP30 by CKII inhibition activates REGγ-20S proteasome-mediated ubiquitin-independent degradation of TRAF6, suppressing osteoclast activity.","method":"Conditional knockout mice (BMM-specific REGγ KO and Traf6 KO), CKII inhibitor (TTP22) treatment, in vitro and in vivo bone loss assays, proteomics","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo genetic rescue with double-KO mice is strong, but the mechanistic detail about NIP30 phosphorylation in this context relies on a single study with limited biochemical dissection of NIP30 itself","pmids":["39536082"],"is_preprint":false},{"year":2012,"finding":"NIP30 (PSME3IP1) selectively interacts with HTLV-1 accessory protein p30 but not with the related HTLV-2 protein p28, as validated by immunoblot following affinity-tag purification and mass spectrometry.","method":"Affinity-tag purification, mass spectrometry, immunoblot validation","journal":"Retrovirology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single co-purification/immunoblot validation, no functional follow-up on NIP30 itself","pmids":["22876852"],"is_preprint":false},{"year":2015,"finding":"GFP-tagged Nip30 (mouse ortholog of PSME3IP1) localizes to the nucleus in C2C12 muscle cells, as shown by direct fluorescence imaging.","method":"GFP-fusion protein transfection and fluorescence microscopy in C2C12 cells","journal":"Gene","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single localization experiment without functional consequence established","pmids":["26497270"],"is_preprint":false}],"current_model":"PSME3IP1 (also known as NIP30/PIP30/FAM192A) functions dually: (1) as a direct regulator of the nuclear PA28γ (REGγ)-20S proteasome, binding PA28γ via its C-terminal serine-rich domain in a CK2 phosphorylation-dependent manner to modulate PA28γ-dependent proteasomal peptide degradation and Cajal body localization, with the phosphorylation state controlled by CDC25A during the cell cycle and DNA damage response; and (2) as a second-step spliceosomal factor (ortholog of yeast Fyv6) that contacts the U2 snRNA–branch site duplex and the Prp22 ATPase in spliceosomal C* complexes, promoting exon ligation and favoring consensus, branch point-distal 3' splice site usage through mutually exclusive exchange with the first-step factor Yju2."},"narrative":{"mechanistic_narrative":"PSME3IP1 (NIP30/PIP30/FAM192A) is a bifunctional nuclear protein operating in two distinct machineries: the nuclear PA28γ (REGγ)–20S proteasome and the spliceosome [PMID:29934401, PMID:35705093]. As a proteasome regulator, it binds PA28γ directly through its C-terminal serine-rich domain in a manner stabilized by CK2 phosphorylation of four conserved serines, thereby increasing PA28γ association with the 20S proteasome, altering PA28γ-dependent peptide degradation, and inhibiting PA28γ recruitment to Cajal bodies by blocking its association with coilin [PMID:29934401, PMID:32764536]. This phosphorylation switch is controlled by the phosphatase CDC25A, coupling PSME3IP1 activity to the cell cycle and DNA damage response and tuning REGγ-mediated, ubiquitin-independent degradation of substrates such as p21 [PMID:32764536]. The same CK2-dependent phosphoswitch operates in osteoclasts, where dephosphorylated NIP30 promotes REGγ-20S degradation of TRAF6 to suppress osteoclast activity [PMID:39536082]. In its second role, PSME3IP1 acts as a second-step (exon-ligation) spliceosomal factor: it contacts the U2 snRNA–branch site duplex in C* intermediate complexes [PMID:35705093] and, as established for its yeast ortholog Fyv6, uniquely contacts the Prp22 ATPase in a manner mutually exclusive with the first-step factor Yju2, promoting exon ligation and favoring consensus, branch point-distal 3' splice site usage [PMID:37625852, PMID:39688371].","teleology":[{"year":2018,"claim":"Established PSME3IP1 as a direct, phosphorylation-dependent binding partner and modulator of the PA28γ-20S proteasome, defining its first molecular function.","evidence":"Direct binding, co-IP, in vitro peptide degradation, CK2 phosphorylation assays, and Cajal body localization imaging","pmids":["29934401"],"confidence":"High","gaps":["Did not define the upstream regulator of the phosphorylation state","Physiological substrate consequences of altered PA28γ activity not addressed"]},{"year":2020,"claim":"Identified the conserved serine-rich domain and its 4-serine phosphorylation as the functional switch, placing PSME3IP1 under CDC25A control during cell cycle and DNA damage and linking it to REGγ-mediated p21 degradation in vivo.","evidence":"Reciprocal co-IP, serine mutagenesis, phosphomimetic/phosphodead mutants, and p53−/− and p53/REGγ double-KO mice","pmids":["32764536"],"confidence":"High","gaps":["Structural basis of the NIP30-REGγ interface not resolved","Full substrate repertoire beyond p21 not mapped"]},{"year":2022,"claim":"Revealed an unanticipated second function by showing FAM192A is a structural component of exon-ligation-stage spliceosomes, contacting the U2 snRNA-branch site duplex.","evidence":"Cryo-EM of human pre-C*-I and pre-C*-II complexes at 3.6 Å","pmids":["35705093"],"confidence":"High","gaps":["Did not establish functional consequence of the contact for splicing outcome","Connection between proteasome and spliceosome roles unaddressed"]},{"year":2023,"claim":"Provided functional and genetic proof via the yeast ortholog Fyv6 that the protein is required for exon ligation and proper 3' splice site selection.","evidence":"FYV6 deletion, genetic interactions with Prp8/Prp16/Prp22, in vitro splicing and in vivo reporter assays","pmids":["37625852"],"confidence":"High","gaps":["Direct human FAM192A functional splicing assays not performed","Mechanism of 3' splice site discrimination not yet structurally defined"]},{"year":2024,"claim":"Defined the structural mechanism: Fyv6 uniquely contacts the Prp22 ATPase mutually exclusively with the first-step factor Yju2, enforcing consensus, branch point-distal 3' splice site usage transcriptome-wide.","evidence":"2.3 Å cryo-EM of yeast product complex, RNA-seq, suppressor screen, structure-guided mutagenesis","pmids":["39688371"],"confidence":"High","gaps":["Human FAM192A-Prp22 contact not directly demonstrated","How the same protein partitions between spliceosomal and proteasomal pools is unknown"]},{"year":2024,"claim":"Extended the proteasome-regulatory axis to a physiological context, showing the CK2-dependent NIP30 phosphoswitch governs REGγ-20S degradation of TRAF6 to control osteoclast activity.","evidence":"BMM-specific REGγ and Traf6 conditional KO mice, CKII inhibitor (TTP22), bone loss assays, proteomics","pmids":["39536082"],"confidence":"Medium","gaps":["Biochemical dissection of NIP30 phosphorylation in this context is limited to one study","Direct demonstration that NIP30 bridges REGγ to TRAF6 is incomplete"]},{"year":null,"claim":"How a single protein is partitioned and regulated between its nuclear proteasome-regulatory and spliceosomal functions, and whether these activities are mechanistically coupled, remains unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No study integrates the proteasome and spliceosome roles","Determinants of pool allocation unknown","Human splicing function shown only structurally, inferred functionally from yeast"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1,5]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[2,3,4]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[2,4]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,7]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[0,1,5]},{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[2,3,4]}],"complexes":["PA28γ (REGγ)-20S proteasome","spliceosome C* complex"],"partners":["PSME3","CSNK2","CDC25A","PRPF22","TRAF6","COIL"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9GZU8","full_name":"PSME3-interacting protein","aliases":["NEFA-interacting nuclear protein NIP30","PA28G-interacting protein"],"length_aa":254,"mass_kda":28.9,"function":"Promotes the association of the proteasome activator complex subunit PSME3 with the 20S proteasome and regulates its activity. Inhibits PSME3-mediated degradation of some proteasome substrates, probably by affecting their diffusion rate into the catalytic chamber of the proteasome. Also inhibits the interaction of PSME3 with COIL, inhibits accumulation of PSME3 in Cajal bodies and positively regulates the number of Cajal bodies in the nucleus","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q9GZU8/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PSME3IP1","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/PSME3IP1","total_profiled":1310},"omim":[],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Vesicles","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PSME3IP1"},"hgnc":{"alias_symbol":["NIP30","PIP30"],"prev_symbol":["C16orf94","FAM192A"]},"alphafold":{"accession":"Q9GZU8","domains":[{"cath_id":"-","chopping":"1-49","consensus_level":"medium","plddt":64.4178,"start":1,"end":49},{"cath_id":"1.20.5","chopping":"52-79","consensus_level":"medium","plddt":89.1571,"start":52,"end":79},{"cath_id":"1.20.5","chopping":"82-123","consensus_level":"medium","plddt":93.6821,"start":82,"end":123}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9GZU8","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9GZU8-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9GZU8-F1-predicted_aligned_error_v6.png","plddt_mean":67.81},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PSME3IP1","jax_strain_url":"https://www.jax.org/strain/search?query=PSME3IP1"},"sequence":{"accession":"Q9GZU8","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9GZU8.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9GZU8/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9GZU8"}},"corpus_meta":[{"pmid":"29934401","id":"PMC_29934401","title":"PIP30/FAM192A is a novel regulator of the nuclear proteasome activator PA28γ.","date":"2018","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/29934401","citation_count":36,"is_preprint":false},{"pmid":"35705093","id":"PMC_35705093","title":"Mechanism of exon ligation by human spliceosome.","date":"2022","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/35705093","citation_count":32,"is_preprint":false},{"pmid":"32764536","id":"PMC_32764536","title":"The REGγ inhibitor NIP30 increases sensitivity to chemotherapy in p53-deficient tumor cells.","date":"2020","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/32764536","citation_count":16,"is_preprint":false},{"pmid":"22876852","id":"PMC_22876852","title":"Comparative host protein interactions with HTLV-1 p30 and HTLV-2 p28: insights into difference in pathobiology of human retroviruses.","date":"2012","source":"Retrovirology","url":"https://pubmed.ncbi.nlm.nih.gov/22876852","citation_count":15,"is_preprint":false},{"pmid":"26497270","id":"PMC_26497270","title":"Isolation, expression analysis and characterization of NEFA-interacting nuclear protein 30 and RING finger and SPRY domain containing 1 in skeletal muscle.","date":"2015","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/26497270","citation_count":12,"is_preprint":false},{"pmid":"30581282","id":"PMC_30581282","title":"Intravitreal bevacizumab upregulates transthyretin in experimental branch retinal vein occlusion.","date":"2018","source":"Molecular vision","url":"https://pubmed.ncbi.nlm.nih.gov/30581282","citation_count":9,"is_preprint":false},{"pmid":"37625852","id":"PMC_37625852","title":"Biochemical and genetic evidence supports Fyv6 as a second-step splicing factor in Saccharomyces cerevisiae.","date":"2023","source":"RNA (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/37625852","citation_count":7,"is_preprint":false},{"pmid":"39536082","id":"PMC_39536082","title":"REGγ is essential to maintain bone homeostasis by degrading TRAF6, preventing osteoporosis.","date":"2024","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/39536082","citation_count":6,"is_preprint":false},{"pmid":"39688371","id":"PMC_39688371","title":"Control of 3' splice site selection by the yeast splicing factor Fyv6.","date":"2024","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/39688371","citation_count":6,"is_preprint":false},{"pmid":"41213311","id":"PMC_41213311","title":"Integrative multi-omics machine learning reveals novel driver genes associations in lung adenocarcinoma.","date":"2025","source":"Biochimica et biophysica acta. Proteins and proteomics","url":"https://pubmed.ncbi.nlm.nih.gov/41213311","citation_count":3,"is_preprint":false},{"pmid":"38273182","id":"PMC_38273182","title":"Genome-Related Mechanisms Contributing to Differences in Alzheimer's Disease Incidence Between White and Black Older US Adults.","date":"2024","source":"Journal of racial and ethnic health disparities","url":"https://pubmed.ncbi.nlm.nih.gov/38273182","citation_count":1,"is_preprint":false},{"pmid":"36778415","id":"PMC_36778415","title":"Biochemical and Genetic Evidence Supports Fyv6 as a Second-Step Splicing Factor in Saccharomyces cerevisiae.","date":"2023","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/36778415","citation_count":0,"is_preprint":false},{"pmid":"38746449","id":"PMC_38746449","title":"Control of 3' splice site selection by the yeast splicing factor Fyv6.","date":"2024","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/38746449","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8657,"output_tokens":2254,"usd":0.029891,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9258,"output_tokens":2540,"usd":0.054895,"stage2_stop_reason":"end_turn"},"total_usd":0.084786,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2018,\n      \"finding\": \"PIP30/FAM192A (PSME3IP1) directly binds PA28γ (REGγ) via its C-terminal end, and this interaction is stabilized by casein kinase 2 (CK2) phosphorylation of PIP30. PIP30 binds to both free and 20S proteasome-associated PA28γ, increases PA28γ association with the 20S proteasome in cells, alters PA28γ-dependent peptide degradation by the 20S proteasome in vitro, and negatively controls PA28γ localization to Cajal bodies by inhibiting its association with coilin.\",\n      \"method\": \"Direct binding assays, co-immunoprecipitation, in vitro peptide degradation assay, phosphorylation assays with CK2, fluorescence microscopy for Cajal body localization\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — multiple orthogonal methods including direct binding assays, in vitro functional assay, co-IP, and cellular localization experiments in a single focused study\",\n      \"pmids\": [\"29934401\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"NIP30 (PSME3IP1) acts as an inhibitor of the REGγ-proteasome by binding to REGγ via an evolutionarily conserved serine-rich domain that undergoes 4-serine phosphorylation. CDC25A phosphatase regulates NIP30 phosphorylation status, and phosphorylated NIP30 modulates REGγ activity during the cell cycle and after DNA damage, controlling REGγ-mediated degradation of the target protein p21 in vivo.\",\n      \"method\": \"Co-immunoprecipitation, site-directed mutagenesis of serine residues, phosphomimetic/phosphodead mutant assays, in vivo validation using p53-/- and p53/REGγ double-knockout mice, cell proliferation and chemosensitivity assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal co-IP, mutagenesis of phosphorylation sites, in vivo genetic rescue with double-KO mice, multiple orthogonal methods\",\n      \"pmids\": [\"32764536\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Human FAM192A (PSME3IP1) functions as a step II spliceosomal factor during exon ligation: cryo-EM structures of pre-C*-I and pre-C*-II spliceosomal complexes show FAM192A contacts the duplex between U2 snRNA and the branch site in both intermediate complexes.\",\n      \"method\": \"Cryo-EM structural analysis of human spliceosomal complexes at 3.6 Å resolution\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — high-resolution cryo-EM structure with defined molecular contacts, single study but structural tier 1 method\",\n      \"pmids\": [\"35705093\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Fyv6, the yeast homolog of human FAM192A (PSME3IP1), functions as a second-step splicing factor: deletion of FYV6 causes genetic interactions with essential splicing factors Prp8, Prp16, and Prp22, accumulation of first-step splicing products in vitro, impaired exon ligation, and altered 3' splice site selection in vivo.\",\n      \"method\": \"Genetic deletion, in vivo reporter splicing assays, in vitro splicing assay with whole-cell extracts, genetic interaction analysis\",\n      \"journal\": \"RNA (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — biochemical in vitro splicing assays combined with multiple genetic epistasis experiments and in vivo reporter assays; published peer-reviewed study\",\n      \"pmids\": [\"37625852\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Fyv6 (yeast homolog of FAM192A/PSME3IP1) is the only second-step spliceosomal factor that contacts the Prp22 ATPase, and its binding is mutually exclusive with that of the first-step factor Yju2. Loss of Fyv6 activates non-consensus, branch point-proximal 3' splice sites transcriptome-wide, and structure-guided domain dissection identified functional domains required for these activities.\",\n      \"method\": \"Cryo-EM structure of yeast product complex spliceosome at 2.3 Å, RNA-seq transcriptome analysis, genetic suppressor screen, structure-guided mutagenesis\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — high-resolution cryo-EM structure combined with transcriptomics, genetics, and mutagenesis in a single integrated study\",\n      \"pmids\": [\"39688371\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"NIP30 (PSME3IP1) participates in a NIP30/REGγ/TRAF6 regulatory axis in osteoclasts: dephosphorylation of NIP30 by CKII inhibition activates REGγ-20S proteasome-mediated ubiquitin-independent degradation of TRAF6, suppressing osteoclast activity.\",\n      \"method\": \"Conditional knockout mice (BMM-specific REGγ KO and Traf6 KO), CKII inhibitor (TTP22) treatment, in vitro and in vivo bone loss assays, proteomics\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo genetic rescue with double-KO mice is strong, but the mechanistic detail about NIP30 phosphorylation in this context relies on a single study with limited biochemical dissection of NIP30 itself\",\n      \"pmids\": [\"39536082\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"NIP30 (PSME3IP1) selectively interacts with HTLV-1 accessory protein p30 but not with the related HTLV-2 protein p28, as validated by immunoblot following affinity-tag purification and mass spectrometry.\",\n      \"method\": \"Affinity-tag purification, mass spectrometry, immunoblot validation\",\n      \"journal\": \"Retrovirology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single co-purification/immunoblot validation, no functional follow-up on NIP30 itself\",\n      \"pmids\": [\"22876852\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"GFP-tagged Nip30 (mouse ortholog of PSME3IP1) localizes to the nucleus in C2C12 muscle cells, as shown by direct fluorescence imaging.\",\n      \"method\": \"GFP-fusion protein transfection and fluorescence microscopy in C2C12 cells\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single localization experiment without functional consequence established\",\n      \"pmids\": [\"26497270\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PSME3IP1 (also known as NIP30/PIP30/FAM192A) functions dually: (1) as a direct regulator of the nuclear PA28γ (REGγ)-20S proteasome, binding PA28γ via its C-terminal serine-rich domain in a CK2 phosphorylation-dependent manner to modulate PA28γ-dependent proteasomal peptide degradation and Cajal body localization, with the phosphorylation state controlled by CDC25A during the cell cycle and DNA damage response; and (2) as a second-step spliceosomal factor (ortholog of yeast Fyv6) that contacts the U2 snRNA–branch site duplex and the Prp22 ATPase in spliceosomal C* complexes, promoting exon ligation and favoring consensus, branch point-distal 3' splice site usage through mutually exclusive exchange with the first-step factor Yju2.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PSME3IP1 (NIP30/PIP30/FAM192A) is a bifunctional nuclear protein operating in two distinct machineries: the nuclear PA28γ (REGγ)–20S proteasome and the spliceosome [#0, #2]. As a proteasome regulator, it binds PA28γ directly through its C-terminal serine-rich domain in a manner stabilized by CK2 phosphorylation of four conserved serines, thereby increasing PA28γ association with the 20S proteasome, altering PA28γ-dependent peptide degradation, and inhibiting PA28γ recruitment to Cajal bodies by blocking its association with coilin [#0, #1]. This phosphorylation switch is controlled by the phosphatase CDC25A, coupling PSME3IP1 activity to the cell cycle and DNA damage response and tuning REGγ-mediated, ubiquitin-independent degradation of substrates such as p21 [#1]. The same CK2-dependent phosphoswitch operates in osteoclasts, where dephosphorylated NIP30 promotes REGγ-20S degradation of TRAF6 to suppress osteoclast activity [#5]. In its second role, PSME3IP1 acts as a second-step (exon-ligation) spliceosomal factor: it contacts the U2 snRNA–branch site duplex in C* intermediate complexes [#2] and, as established for its yeast ortholog Fyv6, uniquely contacts the Prp22 ATPase in a manner mutually exclusive with the first-step factor Yju2, promoting exon ligation and favoring consensus, branch point-distal 3' splice site usage [#3, #4].\",\n  \"teleology\": [\n    {\n      \"year\": 2018,\n      \"claim\": \"Established PSME3IP1 as a direct, phosphorylation-dependent binding partner and modulator of the PA28γ-20S proteasome, defining its first molecular function.\",\n      \"evidence\": \"Direct binding, co-IP, in vitro peptide degradation, CK2 phosphorylation assays, and Cajal body localization imaging\",\n      \"pmids\": [\"29934401\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the upstream regulator of the phosphorylation state\", \"Physiological substrate consequences of altered PA28γ activity not addressed\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identified the conserved serine-rich domain and its 4-serine phosphorylation as the functional switch, placing PSME3IP1 under CDC25A control during cell cycle and DNA damage and linking it to REGγ-mediated p21 degradation in vivo.\",\n      \"evidence\": \"Reciprocal co-IP, serine mutagenesis, phosphomimetic/phosphodead mutants, and p53−/− and p53/REGγ double-KO mice\",\n      \"pmids\": [\"32764536\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the NIP30-REGγ interface not resolved\", \"Full substrate repertoire beyond p21 not mapped\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Revealed an unanticipated second function by showing FAM192A is a structural component of exon-ligation-stage spliceosomes, contacting the U2 snRNA-branch site duplex.\",\n      \"evidence\": \"Cryo-EM of human pre-C*-I and pre-C*-II complexes at 3.6 Å\",\n      \"pmids\": [\"35705093\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish functional consequence of the contact for splicing outcome\", \"Connection between proteasome and spliceosome roles unaddressed\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Provided functional and genetic proof via the yeast ortholog Fyv6 that the protein is required for exon ligation and proper 3' splice site selection.\",\n      \"evidence\": \"FYV6 deletion, genetic interactions with Prp8/Prp16/Prp22, in vitro splicing and in vivo reporter assays\",\n      \"pmids\": [\"37625852\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct human FAM192A functional splicing assays not performed\", \"Mechanism of 3' splice site discrimination not yet structurally defined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defined the structural mechanism: Fyv6 uniquely contacts the Prp22 ATPase mutually exclusively with the first-step factor Yju2, enforcing consensus, branch point-distal 3' splice site usage transcriptome-wide.\",\n      \"evidence\": \"2.3 Å cryo-EM of yeast product complex, RNA-seq, suppressor screen, structure-guided mutagenesis\",\n      \"pmids\": [\"39688371\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Human FAM192A-Prp22 contact not directly demonstrated\", \"How the same protein partitions between spliceosomal and proteasomal pools is unknown\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Extended the proteasome-regulatory axis to a physiological context, showing the CK2-dependent NIP30 phosphoswitch governs REGγ-20S degradation of TRAF6 to control osteoclast activity.\",\n      \"evidence\": \"BMM-specific REGγ and Traf6 conditional KO mice, CKII inhibitor (TTP22), bone loss assays, proteomics\",\n      \"pmids\": [\"39536082\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Biochemical dissection of NIP30 phosphorylation in this context is limited to one study\", \"Direct demonstration that NIP30 bridges REGγ to TRAF6 is incomplete\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How a single protein is partitioned and regulated between its nuclear proteasome-regulatory and spliceosomal functions, and whether these activities are mechanistically coupled, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No study integrates the proteasome and spliceosome roles\", \"Determinants of pool allocation unknown\", \"Human splicing function shown only structurally, inferred functionally from yeast\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1, 5]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [2, 3, 4]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [2, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 7]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 1, 5]},\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [2, 3, 4]}\n    ],\n    \"complexes\": [\"PA28γ (REGγ)-20S proteasome\", \"spliceosome C* complex\"],\n    \"partners\": [\"PSME3\", \"CSNK2\", \"CDC25A\", \"PRPF22\", \"TRAF6\", \"COIL\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}