{"gene":"POLR3C","run_date":"2026-04-28T19:45:44","timeline":{"discoveries":[{"year":1997,"finding":"Human RPC32 (POLR3C), RPC39, and RPC62 form a stable subcomplex that is specific to RNA Pol III. This subcomplex dissociates from the Pol III core under partial denaturing/high-salt conditions. The core lacking the subcomplex can perform elongation and termination on a tailed template but cannot perform promoter-dependent transcription initiation; specific initiation is restored by adding back the natural or recombinant RPC32/RPC39/RPC62 subcomplex. RPC39 within the subcomplex physically interacts with hTBP and hTFIIIB90, suggesting the subcomplex directs Pol III binding to the TFIIIB–DNA complex.","method":"Immunopurification, sucrose gradient sedimentation, reconstituted in vitro transcription assays with recombinant subcomplex, direct binding assays","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 1 — reconstituted in vitro transcription with defined subcomplex plus mutagenesis/binding assays; foundational study","pmids":["9171375"],"is_preprint":false},{"year":1999,"finding":"The TFIIIC90 subunit of human TFIIIC interacts directly with the RPC39 (POLR3D) and RPC62 (POLR3F) subunits of the Pol III initiation-specific subcomplex that contains POLR3C (RPC32), providing a physical link between TFIIIC and the Pol III holoenzyme during preinitiation complex assembly.","method":"Immunodepletion, immunoprecipitation, in vitro interaction assays","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2 — reciprocal Co-IP/pulldown with functional context; interaction mapped to subcomplex containing POLR3C","pmids":["10523658"],"is_preprint":false},{"year":2001,"finding":"Plakophilin 2, a dual-location desmosomal/nuclear protein, is present in the Pol III holoenzyme but not the core complex, and it co-immunoselects with other Pol III subunits and TFIIIB. Because the holoenzyme but not the core contains the RPC32/RPC39/RPC62 subcomplex (which includes POLR3C), this association places plakophilin 2 in a nuclear particle containing the POLR3C-containing subcomplex.","method":"Co-immunoprecipitation, in vitro binding assay with RPC155, sucrose gradient co-sedimentation","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2/3 — Co-IP and in vitro binding; POLR3C-containing holoenzyme implicated by context","pmids":["11416169"],"is_preprint":false},{"year":2015,"finding":"Crystal structure of the human RPC62–RPC32β (POLR3F–POLR3C) complex was solved. RPC32β (POLR3C) uses a core-interacting domain to associate with the extended winged-helix 1 and 2 (eWH1/2) domains and the coiled-coil domain of RPC62. POLR3C acts as a molecular bridge between the RPC62 domains. Fitting the complex into Pol III EM density indicates that POLR3C has a bi-functional role: contacting the largest Pol III subunit and exposing solvent-facing residues for additional interactions.","method":"X-ray crystallography, fitting into EM density","journal":"Journal of structural biology","confidence":"High","confidence_rationale":"Tier 1 — crystal structure with functional domain mapping","pmids":["26394183"],"is_preprint":false},{"year":2017,"finding":"Heterozygous missense mutations in POLR3C confer increased susceptibility to severe varicella zoster virus (VZV) infection. Leukocytes from a patient with a POLR3C mutation showed impaired IFN induction in response to synthetic DNA and VZV-derived DNA, defective IFN production upon VZV infection, and reduced control of VZV replication. These phenotypes were rescued by transduction with the wild-type POLR3C allele, establishing that POLR3C is required for the RNA Pol III-dependent DNA-sensing pathway that triggers innate IFN responses.","method":"Patient leukocyte functional assays (IFN induction, viral replication), lentiviral rescue with WT allele","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 — loss-of-function in primary human cells with defined phenotype and allele-specific rescue","pmids":["28783042"],"is_preprint":false},{"year":2021,"finding":"Cryo-EM structures of human RNA Pol III (2.8–3.3 Å) in unbound and transcribing states resolved the heterotrimer subcomplex containing POLR3C (RPC32). An iron-sulfur cluster was identified that tethers the heterotrimer subcomplex (including POLR3C) to the Pol III core, an element absent in yeast Pol III. The structures enabled mapping of disease-related mutations within POLR3C and the wider complex.","method":"Cryo-electron microscopy, structural modelling","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 — near-atomic resolution cryo-EM structures with functional annotation of subunit contacts","pmids":["33558764"],"is_preprint":false},{"year":2024,"finding":"In trypanosomatid parasites (T. brucei and L. major), the C82 subunit (ortholog of human POLR3C) localizes to the nucleus, binds Pol III-dependent genes (tRNA, 5S rRNA loci), and forms a stable subcomplex with the C34 ortholog. Knock-down by RNAi significantly reduced tRNA and 5S rRNA levels and caused cell death in procyclic T. brucei. Tandem affinity purifications identified C34 and genus-specific putative regulators as interacting partners, but no C31 ortholog was detected, indicating divergence from the canonical three-subunit subcomplex.","method":"Chromatin immunoprecipitation, RNA interference knockdown, tandem affinity purification–mass spectrometry, immunofluorescence localization","journal":"Parasitology","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal methods in a divergent ortholog; functional conservation of POLR3C-like subunit confirmed by RNAi phenotype and rescue","pmids":["39523652"],"is_preprint":false}],"current_model":"POLR3C (RPC32) is a subunit of the RNA Pol III-specific heterotrimer (RPC32/RPC39/RPC62) that is required for promoter-dependent transcription initiation; it acts as a structural bridge within the heterotrimer by contacting RPC62 through its eWH and coiled-coil domains, and the heterotrimer is tethered to the Pol III core via an iron-sulfur cluster; additionally, POLR3C is essential for the Pol III-dependent cytosolic DNA-sensing pathway that drives innate interferon responses against viral pathogens such as VZV."},"narrative":{"teleology":[{"year":1997,"claim":"Establishing that POLR3C resides in a Pol III-specific subcomplex required for promoter-dependent initiation resolved how Pol III distinguishes initiation from elongation at a subunit level.","evidence":"Immunopurification and reconstituted in vitro transcription with recombinant RPC32/RPC39/RPC62 subcomplex in human cell-free systems","pmids":["9171375"],"confidence":"High","gaps":["Structural basis of how the subcomplex contacts the Pol III core was unknown","Individual contributions of RPC32 versus RPC39/RPC62 to initiation were not separated"]},{"year":1999,"claim":"Demonstrating that TFIIIC90 contacts RPC39 and RPC62 within the POLR3C-containing subcomplex provided a physical mechanism linking TFIIIC recognition of internal promoter elements to Pol III recruitment.","evidence":"Immunodepletion, reciprocal immunoprecipitation, and in vitro interaction assays","pmids":["10523658"],"confidence":"Medium","gaps":["Whether POLR3C itself makes direct contacts with TFIIIC was not tested","Stoichiometry of the TFIIIC–subcomplex interaction was not determined"]},{"year":2015,"claim":"Solving the crystal structure of the RPC62–POLR3C binary complex revealed that POLR3C bridges multiple domains of RPC62 and exposes solvent-facing residues, defining its architectural role within the heterotrimer.","evidence":"X-ray crystallography of human RPC62–RPC32β complex fitted into Pol III EM density","pmids":["26394183"],"confidence":"High","gaps":["The structure lacked the third subunit RPC39, leaving the complete heterotrimer architecture unresolved","Functional validation of solvent-exposed interaction surfaces was not performed"]},{"year":2017,"claim":"Identifying heterozygous POLR3C mutations in patients with severe VZV infection, and rescuing the IFN-induction defect with wild-type allele, established a non-canonical role for Pol III-dependent DNA sensing in antiviral innate immunity.","evidence":"Primary patient leukocyte functional assays measuring IFN induction and viral replication, with lentiviral rescue","pmids":["28783042"],"confidence":"High","gaps":["Whether the immune phenotype reflects a specific POLR3C function beyond its role in the heterotrimer is unknown","Genotype–phenotype correlation across additional POLR3C variants remains unexplored"]},{"year":2021,"claim":"Near-atomic cryo-EM structures of human Pol III revealed a human-specific iron-sulfur cluster that tethers the POLR3C-containing heterotrimer to the core, explaining a key structural divergence from yeast Pol III.","evidence":"Cryo-EM at 2.8–3.3 Å resolution of unbound and transcribing human Pol III","pmids":["33558764"],"confidence":"High","gaps":["Functional consequences of disrupting the iron-sulfur cluster have not been tested","How disease mutations mapped onto the structure alter initiation kinetics is unknown"]},{"year":2024,"claim":"Functional conservation of the POLR3C ortholog in trypanosomatids confirmed its essential role in Pol III transcription across deeply divergent eukaryotes, while revealing lineage-specific differences such as the absence of a C31 ortholog.","evidence":"ChIP, RNAi knockdown, tandem affinity purification–mass spectrometry, and immunofluorescence in T. brucei and L. major","pmids":["39523652"],"confidence":"Medium","gaps":["Degree to which parasite-specific interactors are functionally equivalent to human heterotrimer components is unknown","Cross-species complementation has not been attempted"]},{"year":null,"claim":"The mechanism by which POLR3C specifically contributes to cytosolic DNA sensing — whether via a moonlighting function or solely through its role in the Pol III heterotrimer — and the structural basis of disease-causing mutations' effects on initiation kinetics remain unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No separation-of-function mutants distinguish POLR3C's transcription-initiation role from its innate immunity role","No kinetic or single-molecule studies on heterotrimer–promoter engagement exist","The functional significance of the iron-sulfur cluster for initiation versus complex stability has not been dissected"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[0,3,5]},{"term_id":"GO:0140223","term_label":"general transcription initiation factor activity","supporting_discovery_ids":[0,1]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[6]},{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[3,5]}],"pathway":[{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,1,3,5,6]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[4]}],"complexes":["RNA Pol III holoenzyme","RPC32/RPC39/RPC62 heterotrimer"],"partners":["POLR3F","POLR3D","POLR3A","PKP2"],"other_free_text":[]},"mechanistic_narrative":"POLR3C (RPC32) is a dedicated subunit of the RNA polymerase III initiation-specific heterotrimer (RPC32/RPC39/RPC62) that is essential for promoter-dependent transcription of tRNA, 5S rRNA, and other Pol III gene classes. The heterotrimer dissociates from the Pol III core under denaturing conditions and, when added back, restores specific transcription initiation, with RPC39 bridging TFIIIB and TFIIIC to direct the polymerase to promoters [PMID:9171375, PMID:10523658]. Structurally, POLR3C acts as a molecular bridge within the heterotrimer by contacting the eWH and coiled-coil domains of RPC62, and the subcomplex is tethered to the Pol III core via a human-specific iron-sulfur cluster [PMID:26394183, PMID:33558764]. Heterozygous loss-of-function mutations in POLR3C cause impaired RNA Pol III-dependent cytosolic DNA sensing with defective interferon induction, conferring susceptibility to severe varicella zoster virus infection [PMID:28783042]."},"prefetch_data":{"uniprot":{"accession":"Q9BUI4","full_name":"DNA-directed RNA polymerase III subunit RPC3","aliases":["DNA-directed RNA polymerase III subunit C","RNA polymerase III 62 kDa subunit","RPC62"],"length_aa":534,"mass_kda":60.6,"function":"DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates (PubMed:20413673, PubMed:33558764, PubMed:33558766, PubMed:34675218, PubMed:35637192). Specific peripheric component of RNA polymerase III (Pol III) which synthesizes small non-coding RNAs including 5S rRNA, snRNAs, tRNAs and miRNAs from at least 500 distinct genomic loci (PubMed:20413673, PubMed:33558764, PubMed:33558766, PubMed:35637192). Part of POLR3C/RPC3-POLR3F/RPC6-POLR3G/RPC7 heterotrimer, coordinates the dynamics of Pol III stalk and clamp modules during the transition from apo to elongation state (PubMed:33558764, PubMed:33558766). Pol III plays a key role in sensing and limiting infection by intracellular bacteria and DNA viruses. Acts as a nuclear and cytosolic DNA sensor involved in innate immune response. Can sense non-self dsDNA that serves as template for transcription into dsRNA. The non-self RNA polymerase III transcripts, such as Epstein-Barr virus-encoded RNAs (EBERs) induce type I interferon and NF-kappa-B through the RIG-I pathway (PubMed:19609254, PubMed:19631370). Preferentially binds single-stranded DNA (ssDNA) in a sequence-independent manner (PubMed:21358628)","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q9BUI4/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/POLR3C","classification":"Common Essential","n_dependent_lines":1155,"n_total_lines":1208,"dependency_fraction":0.9561258278145696},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000186141","cell_line_id":"CID000711","localizations":[{"compartment":"nucleoplasm","grade":3}],"interactors":[{"gene":"POLR1C","stoichiometry":10.0},{"gene":"POLR1D","stoichiometry":10.0},{"gene":"POLR2F","stoichiometry":10.0},{"gene":"POLR2H","stoichiometry":10.0},{"gene":"POLR2K","stoichiometry":10.0},{"gene":"POLR3A","stoichiometry":10.0},{"gene":"POLR3B","stoichiometry":10.0},{"gene":"POLR3H","stoichiometry":10.0},{"gene":"POLR3F","stoichiometry":10.0},{"gene":"POLR3G","stoichiometry":10.0}],"url":"https://opencell.sf.czbiohub.org/target/CID000711","total_profiled":1310},"omim":[{"mim_id":"617456","title":"POLYMERASE III, RNA, SUBUNIT G; POLR3G","url":"https://www.omim.org/entry/617456"},{"mim_id":"617454","title":"POLYMERASE III, RNA, SUBUNIT C; POLR3C","url":"https://www.omim.org/entry/617454"},{"mim_id":"614258","title":"POLYMERASE III, RNA, SUBUNIT A; POLR3A","url":"https://www.omim.org/entry/614258"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Nucleoplasm","reliability":"Enhanced"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/POLR3C"},"hgnc":{"alias_symbol":["RPC62","RPC3","C82"],"prev_symbol":[]},"alphafold":{"accession":"Q9BUI4","domains":[{"cath_id":"1.10.10.10","chopping":"2-78","consensus_level":"high","plddt":94.6065,"start":2,"end":78},{"cath_id":"1.10.10.10","chopping":"86-164_183-201_232-237","consensus_level":"medium","plddt":92.1298,"start":86,"end":237},{"cath_id":"1.10.10.10","chopping":"241-336","consensus_level":"high","plddt":92.8897,"start":241,"end":336},{"cath_id":"1.10.10.10","chopping":"340-426","consensus_level":"medium","plddt":93.5274,"start":340,"end":426},{"cath_id":"1.10.287","chopping":"436-474_487-531","consensus_level":"high","plddt":92.7145,"start":436,"end":531}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BUI4","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BUI4-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BUI4-F1-predicted_aligned_error_v6.png","plddt_mean":89.06},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=POLR3C","jax_strain_url":"https://www.jax.org/strain/search?query=POLR3C"},"sequence":{"accession":"Q9BUI4","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9BUI4.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9BUI4/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BUI4"}},"corpus_meta":[{"pmid":"19403166","id":"PMC_19403166","title":"The 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abundances.","date":"2015","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/26496610","citation_count":1015,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"25416956","id":"PMC_25416956","title":"A proteome-scale map of the human interactome network.","date":"2014","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/25416956","citation_count":977,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"32296183","id":"PMC_32296183","title":"A reference map of the human binary protein interactome.","date":"2020","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/32296183","citation_count":849,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"19609254","id":"PMC_19609254","title":"RIG-I-dependent sensing of poly(dA:dT) through the induction of an RNA polymerase III-transcribed RNA intermediate.","date":"2009","source":"Nature immunology","url":"https://pubmed.ncbi.nlm.nih.gov/19609254","citation_count":712,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"33961781","id":"PMC_33961781","title":"Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.","date":"2021","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/33961781","citation_count":705,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"22939629","id":"PMC_22939629","title":"A census of human soluble protein complexes.","date":"2012","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/22939629","citation_count":689,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"21873635","id":"PMC_21873635","title":"Phylogenetic-based propagation of functional annotations within the Gene Ontology consortium.","date":"2011","source":"Briefings in 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N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/35271311","citation_count":432,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"16344560","id":"PMC_16344560","title":"Diversification of transcriptional modulation: large-scale identification and characterization of putative alternative promoters of human genes.","date":"2005","source":"Genome research","url":"https://pubmed.ncbi.nlm.nih.gov/16344560","citation_count":409,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"26344197","id":"PMC_26344197","title":"Panorama of ancient metazoan macromolecular complexes.","date":"2015","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/26344197","citation_count":407,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"17643375","id":"PMC_17643375","title":"Systematic analysis of the protein interaction network for the human transcription machinery reveals the identity of the 7SK capping enzyme.","date":"2007","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/17643375","citation_count":367,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"34079125","id":"PMC_34079125","title":"A proximity-dependent biotinylation map of a human cell.","date":"2021","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/34079125","citation_count":339,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"29568061","id":"PMC_29568061","title":"An AP-MS- and BioID-compatible MAC-tag enables comprehensive mapping of protein interactions and subcellular localizations.","date":"2018","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/29568061","citation_count":201,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"32416067","id":"PMC_32416067","title":"Synthetic Lethal and Resistance Interactions with BET Bromodomain Inhibitors in Triple-Negative Breast Cancer.","date":"2020","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/32416067","citation_count":159,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"30415952","id":"PMC_30415952","title":"MYC Protein Interactome Profiling Reveals Functionally Distinct Regions that Cooperate to Drive Tumorigenesis.","date":"2018","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/30415952","citation_count":152,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"30554943","id":"PMC_30554943","title":"Interactome Rewiring Following Pharmacological Targeting of BET Bromodomains.","date":"2018","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/30554943","citation_count":136,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"9171375","id":"PMC_9171375","title":"Three human RNA polymerase III-specific subunits form a subcomplex with a selective function in specific transcription initiation.","date":"1997","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/9171375","citation_count":132,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"21832049","id":"PMC_21832049","title":"Interactions of pathological hallmark proteins: tubulin polymerization promoting protein/p25, beta-amyloid, and alpha-synuclein.","date":"2011","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21832049","citation_count":131,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"28783042","id":"PMC_28783042","title":"Inborn errors in RNA polymerase III underlie severe varicella zoster virus infections.","date":"2017","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/28783042","citation_count":126,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"18029348","id":"PMC_18029348","title":"Toward a confocal subcellular atlas of the human proteome.","date":"2007","source":"Molecular & cellular proteomics : MCP","url":"https://pubmed.ncbi.nlm.nih.gov/18029348","citation_count":114,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"30021884","id":"PMC_30021884","title":"Histone Interaction Landscapes Visualized by Crosslinking Mass Spectrometry in Intact Cell Nuclei.","date":"2018","source":"Molecular & cellular proteomics : MCP","url":"https://pubmed.ncbi.nlm.nih.gov/30021884","citation_count":101,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"11416169","id":"PMC_11416169","title":"Nuclear particles containing RNA polymerase III complexes associated with the junctional plaque protein plakophilin 2.","date":"2001","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/11416169","citation_count":98,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"10523658","id":"PMC_10523658","title":"The TFIIIC90 subunit of TFIIIC interacts with multiple components of the RNA polymerase III machinery and contains a histone-specific acetyltransferase activity.","date":"1999","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/10523658","citation_count":86,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"33558764","id":"PMC_33558764","title":"Cryo-EM structures of human RNA polymerase III in its unbound and transcribing states.","date":"2021","source":"Nature structural & molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/33558764","citation_count":80,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"35652658","id":"PMC_35652658","title":"SARS-CoV-2 N Protein Antagonizes Stress Granule Assembly and IFN Production by Interacting with G3BPs to Facilitate Viral Replication.","date":"2022","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/35652658","citation_count":75,"is_preprint":false,"source_track":"gene2pubmed"}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":16434,"output_tokens":1051,"usd":0.032533},"stage2":{"model":"claude-opus-4-6","input_tokens":3921,"output_tokens":2306,"usd":0.115882},"total_usd":0.320347,"stage1_batch_id":"msgbatch_01SUR8NDzVrNmyszWyJeCct7","stage2_batch_id":"msgbatch_01G7Yfutko3cDWzejrwH5AMx","note":"batch pricing = 50% of standard","round2_stage1":{"model":"claude-sonnet-4-6","input_tokens":28221,"output_tokens":2052,"usd":0.057722},"round2_rules_fired":"R3","round2_stage2":{"model":"claude-opus-4-6","input_tokens":5578,"output_tokens":1930,"usd":0.11421}},"stage1_raw":"Looking at the corpus, I need to identify papers about POLR3C (RNA Polymerase III subunit C, also known as RPC32 or RPC62 region). \n\nThe gene POLR3C encodes RPC62, a subunit of RNA Polymerase III. Let me scan the abstracts:\n\n- Paper [14] (PMID: 26394183) describes the structural analysis of human RPC32β-RPC62 complex, which is directly relevant to POLR3C (RPC62).\n- Paper [27] (PMID: 39523652) describes the C82 subunit of RNA Polymerase III in trypanosomatids - this could be an ortholog study.\n\nAll other papers are clearly about Gd@C82 nanoparticles, fullerenes, DNA adducts, Wnt inhibitor C-82, or bacteriochlorophyll - none of these are related to POLR3C.\n\nPaper [14] is directly about RPC62 (POLR3C) and RPC32β interaction, with crystal structure data.\nPaper [27] is about C82 subunit in Trypanosoma/Leishmania - these are trypanosomatid parasites, not typical model organisms for mammalian gene function. However, the functional context (RNAP III subunit) is consistent with the mammalian gene.\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2015,\n      \"finding\": \"Crystal structure of the human RPC62–RPC32β complex revealed that RPC32β associates with the extended winged helix 1 and 2 (eWH1/2) and coiled-coil domains of RPC62, functioning as a molecular bridge between RPC62 domains. A core-interacting domain of RPC32β sufficient for the interaction with RPC62 was identified, and fitting of the complex into EM data suggested a bi-functional role for RPC32 through interactions with the largest Pol III subunit and through solvent-exposed residues.\",\n      \"method\": \"X-ray crystallography of recombinant RPC62–RPC32β core domain complex, fitting into EM density map\",\n      \"journal\": \"Journal of structural biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure with domain mapping and EM fitting providing structural validation\",\n      \"pmids\": [\"26394183\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In trypanosomatid orthologs of POLR3C (C82 subunit), C82 localizes to the nucleus, binds RNAP III-dependent genes (tRNA and 5S rRNA loci), and is essential for tRNA and 5S rRNA production; knockdown by RNAi causes death of procyclic T. brucei. Tandem affinity purification identified C34 as a conserved C82-interacting partner (consistent with mammalian RPC62/RPC32/RPC39 subcomplex), though the C31 ortholog was absent in trypanosomatids. The four eWH domains and coiled-coil motif of C82 are conserved in these organisms.\",\n      \"method\": \"RNAi knockdown with RT-qPCR readout of tRNA/5S rRNA levels; tandem affinity purification/mass spectrometry; chromatin immunoprecipitation; nuclear localization by microscopy\",\n      \"journal\": \"Parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (RNAi + TAP-MS + ChIP + localization) in trypanosomatid ortholog; single study\",\n      \"pmids\": [\"39523652\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"POLR3C (RPC62) is a subunit of the RNA Polymerase III holoenzyme that forms a stable subcomplex with RPC32 and RPC39; structurally, RPC32β acts as a molecular bridge across RPC62's eWH and coiled-coil domains, and the subcomplex is required for promoter-specific transcription initiation to produce essential non-coding RNAs including tRNAs and 5S rRNA.\"\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1997,\n      \"finding\": \"Human RPC32 (POLR3C), RPC39, and RPC62 form a stable subcomplex that is specific to RNA Pol III. This subcomplex dissociates from the Pol III core under partial denaturing/high-salt conditions. The core lacking the subcomplex can perform elongation and termination on a tailed template but cannot perform promoter-dependent transcription initiation; specific initiation is restored by adding back the natural or recombinant RPC32/RPC39/RPC62 subcomplex. RPC39 within the subcomplex physically interacts with hTBP and hTFIIIB90, suggesting the subcomplex directs Pol III binding to the TFIIIB–DNA complex.\",\n      \"method\": \"Immunopurification, sucrose gradient sedimentation, reconstituted in vitro transcription assays with recombinant subcomplex, direct binding assays\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro transcription with defined subcomplex plus mutagenesis/binding assays; foundational study\",\n      \"pmids\": [\"9171375\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"The TFIIIC90 subunit of human TFIIIC interacts directly with the RPC39 (POLR3D) and RPC62 (POLR3F) subunits of the Pol III initiation-specific subcomplex that contains POLR3C (RPC32), providing a physical link between TFIIIC and the Pol III holoenzyme during preinitiation complex assembly.\",\n      \"method\": \"Immunodepletion, immunoprecipitation, in vitro interaction assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP/pulldown with functional context; interaction mapped to subcomplex containing POLR3C\",\n      \"pmids\": [\"10523658\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Plakophilin 2, a dual-location desmosomal/nuclear protein, is present in the Pol III holoenzyme but not the core complex, and it co-immunoselects with other Pol III subunits and TFIIIB. Because the holoenzyme but not the core contains the RPC32/RPC39/RPC62 subcomplex (which includes POLR3C), this association places plakophilin 2 in a nuclear particle containing the POLR3C-containing subcomplex.\",\n      \"method\": \"Co-immunoprecipitation, in vitro binding assay with RPC155, sucrose gradient co-sedimentation\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2/3 — Co-IP and in vitro binding; POLR3C-containing holoenzyme implicated by context\",\n      \"pmids\": [\"11416169\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Crystal structure of the human RPC62–RPC32β (POLR3F–POLR3C) complex was solved. RPC32β (POLR3C) uses a core-interacting domain to associate with the extended winged-helix 1 and 2 (eWH1/2) domains and the coiled-coil domain of RPC62. POLR3C acts as a molecular bridge between the RPC62 domains. Fitting the complex into Pol III EM density indicates that POLR3C has a bi-functional role: contacting the largest Pol III subunit and exposing solvent-facing residues for additional interactions.\",\n      \"method\": \"X-ray crystallography, fitting into EM density\",\n      \"journal\": \"Journal of structural biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure with functional domain mapping\",\n      \"pmids\": [\"26394183\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Heterozygous missense mutations in POLR3C confer increased susceptibility to severe varicella zoster virus (VZV) infection. Leukocytes from a patient with a POLR3C mutation showed impaired IFN induction in response to synthetic DNA and VZV-derived DNA, defective IFN production upon VZV infection, and reduced control of VZV replication. These phenotypes were rescued by transduction with the wild-type POLR3C allele, establishing that POLR3C is required for the RNA Pol III-dependent DNA-sensing pathway that triggers innate IFN responses.\",\n      \"method\": \"Patient leukocyte functional assays (IFN induction, viral replication), lentiviral rescue with WT allele\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — loss-of-function in primary human cells with defined phenotype and allele-specific rescue\",\n      \"pmids\": [\"28783042\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Cryo-EM structures of human RNA Pol III (2.8–3.3 Å) in unbound and transcribing states resolved the heterotrimer subcomplex containing POLR3C (RPC32). An iron-sulfur cluster was identified that tethers the heterotrimer subcomplex (including POLR3C) to the Pol III core, an element absent in yeast Pol III. The structures enabled mapping of disease-related mutations within POLR3C and the wider complex.\",\n      \"method\": \"Cryo-electron microscopy, structural modelling\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — near-atomic resolution cryo-EM structures with functional annotation of subunit contacts\",\n      \"pmids\": [\"33558764\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In trypanosomatid parasites (T. brucei and L. major), the C82 subunit (ortholog of human POLR3C) localizes to the nucleus, binds Pol III-dependent genes (tRNA, 5S rRNA loci), and forms a stable subcomplex with the C34 ortholog. Knock-down by RNAi significantly reduced tRNA and 5S rRNA levels and caused cell death in procyclic T. brucei. Tandem affinity purifications identified C34 and genus-specific putative regulators as interacting partners, but no C31 ortholog was detected, indicating divergence from the canonical three-subunit subcomplex.\",\n      \"method\": \"Chromatin immunoprecipitation, RNA interference knockdown, tandem affinity purification–mass spectrometry, immunofluorescence localization\",\n      \"journal\": \"Parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods in a divergent ortholog; functional conservation of POLR3C-like subunit confirmed by RNAi phenotype and rescue\",\n      \"pmids\": [\"39523652\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"POLR3C (RPC32) is a subunit of the RNA Pol III-specific heterotrimer (RPC32/RPC39/RPC62) that is required for promoter-dependent transcription initiation; it acts as a structural bridge within the heterotrimer by contacting RPC62 through its eWH and coiled-coil domains, and the heterotrimer is tethered to the Pol III core via an iron-sulfur cluster; additionally, POLR3C is essential for the Pol III-dependent cytosolic DNA-sensing pathway that drives innate interferon responses against viral pathogens such as VZV.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"POLR3C (RPC62) is a subunit of RNA Polymerase III that forms a stable heterotrimer with RPC32 and RPC39, required for promoter-specific transcription initiation of tRNA and 5S rRNA genes [PMID:39523652]. The crystal structure of the RPC62–RPC32β complex shows that RPC32β bridges the extended winged helix (eWH1/2) and coiled-coil domains of RPC62, positioning RPC32 for dual interactions with RPC62 and the largest Pol III subunit [PMID:26394183]. The eWH domains and coiled-coil motif of RPC62 are structurally conserved across eukaryotes, and loss of function is lethal, consistent with an essential role in non-coding RNA biogenesis [PMID:39523652].\",\n  \"teleology\": [\n    {\n      \"year\": 2015,\n      \"claim\": \"Determining how RPC32 engages RPC62 within the Pol III-specific subcomplex: the crystal structure revealed that RPC32β acts as a molecular bridge spanning the eWH1/2 and coiled-coil domains of RPC62, establishing the architectural basis of the heterotrimer and suggesting a bi-functional role for RPC32 in connecting RPC62 to the catalytic core.\",\n      \"evidence\": \"X-ray crystallography of recombinant human RPC62–RPC32β core domain complex with fitting into EM density of Pol III\",\n      \"pmids\": [\"26394183\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"RPC39 was not present in the crystal structure; the complete ternary subcomplex structure remains unresolved\",\n        \"Functional consequences of disrupting the RPC32β bridge on transcription initiation were not tested\",\n        \"No mutagenesis data validating the predicted contact interface with the largest Pol III subunit\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Establishing that the RPC62 ortholog is essential for Pol III-dependent transcription in vivo: knockdown of C82 in trypanosomatids abolished tRNA and 5S rRNA production and was lethal, confirming that the conserved eWH/coiled-coil architecture is functionally required for Pol III transcription across eukaryotes.\",\n      \"evidence\": \"RNAi knockdown with RT-qPCR, tandem affinity purification/mass spectrometry, ChIP, and nuclear localization microscopy in T. brucei\",\n      \"pmids\": [\"39523652\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Functional essentiality demonstrated only in trypanosomatids; analogous loss-of-function data in mammalian cells not reported\",\n        \"C31/RPC39 ortholog absent in trypanosomatids, so the full trimeric subcomplex requirement cannot be assessed in this system\",\n        \"Mechanism by which RPC62/C82 contributes to promoter recognition versus open complex formation is unresolved\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The precise mechanism by which the RPC62–RPC32–RPC39 subcomplex recognizes promoter DNA and communicates with the Pol III catalytic core to initiate transcription remains to be structurally and functionally dissected in human cells.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No high-resolution structure of the complete human RPC62–RPC32–RPC39 trimer bound to promoter DNA\",\n        \"No mammalian loss-of-function or rescue experiments specifically targeting POLR3C\",\n        \"Relationship between POLR3C mutations and human disease has not been established\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0074160\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"complexes\": [\"RNA Polymerase III\", \"RPC62–RPC32–RPC39 subcomplex\"],\n    \"partners\": [\"POLR3F\", \"POLR3G\"],\n    \"other_free_text\": []\n  }\n}\n```\n\nWait, let me correct the pathway term_id. The allowed Reactome pathway for gene expression/transcription is `R-HSA-74160`, not a GO term. Let me fix that.\n\n```json\n{\n  \"mechanistic_narrative\": \"POLR3C (RPC62) is a subunit of RNA Polymerase III that forms a stable heterotrimer with RPC32 and RPC39, required for promoter-specific transcription initiation of tRNA and 5S rRNA genes [PMID:39523652]. The crystal structure of the RPC62–RPC32β complex shows that RPC32β bridges the extended winged helix (eWH1/2) and coiled-coil domains of RPC62, positioning RPC32 for dual interactions with RPC62 and the largest Pol III subunit [PMID:26394183]. The eWH domains and coiled-coil motif of RPC62 are structurally conserved across eukaryotes, and loss of function is lethal, consistent with an essential role in non-coding RNA biogenesis [PMID:39523652].\",\n  \"teleology\": [\n    {\n      \"year\": 2015,\n      \"claim\": \"Determining how RPC32 engages RPC62 within the Pol III-specific subcomplex: the crystal structure revealed that RPC32β acts as a molecular bridge spanning the eWH1/2 and coiled-coil domains of RPC62, establishing the architectural basis of the heterotrimer and suggesting a bi-functional role for RPC32 in connecting RPC62 to the catalytic core.\",\n      \"evidence\": \"X-ray crystallography of recombinant human RPC62–RPC32β core domain complex with fitting into EM density of Pol III\",\n      \"pmids\": [\"26394183\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"RPC39 was not present in the crystal structure; the complete ternary subcomplex structure remains unresolved\",\n        \"Functional consequences of disrupting the RPC32β bridge on transcription initiation were not tested\",\n        \"No mutagenesis data validating the predicted contact interface with the largest Pol III subunit\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Establishing that the RPC62 ortholog is essential for Pol III-dependent transcription in vivo: knockdown of C82 in trypanosomatids abolished tRNA and 5S rRNA production and was lethal, confirming that the conserved eWH/coiled-coil architecture is functionally required for Pol III transcription across eukaryotes.\",\n      \"evidence\": \"RNAi knockdown with RT-qPCR, tandem affinity purification/mass spectrometry, ChIP, and nuclear localization microscopy in T. brucei\",\n      \"pmids\": [\"39523652\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Functional essentiality demonstrated only in trypanosomatids; analogous loss-of-function data in mammalian cells not reported\",\n        \"C31/RPC39 ortholog absent in trypanosomatids, so the full trimeric subcomplex requirement cannot be assessed in this system\",\n        \"Mechanism by which RPC62/C82 contributes to promoter recognition versus open complex formation is unresolved\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The precise mechanism by which the RPC62–RPC32–RPC39 subcomplex recognizes promoter DNA and communicates with the Pol III catalytic core to initiate transcription remains to be structurally and functionally dissected in human cells.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No high-resolution structure of the complete human RPC62–RPC32–RPC39 trimer bound to promoter DNA\",\n        \"No mammalian loss-of-function or rescue experiments specifically targeting POLR3C\",\n        \"Relationship between POLR3C mutations and human disease has not been established\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"complexes\": [\"RNA Polymerase III\", \"RPC62-RPC32-RPC39 subcomplex\"],\n    \"partners\": [\"POLR3F\", \"POLR3G\"],\n    \"other_free_text\": []\n  }\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"mechanistic_narrative\": \"POLR3C (RPC32) is a dedicated subunit of the RNA polymerase III initiation-specific heterotrimer (RPC32/RPC39/RPC62) that is essential for promoter-dependent transcription of tRNA, 5S rRNA, and other Pol III gene classes. The heterotrimer dissociates from the Pol III core under denaturing conditions and, when added back, restores specific transcription initiation, with RPC39 bridging TFIIIB and TFIIIC to direct the polymerase to promoters [PMID:9171375, PMID:10523658]. Structurally, POLR3C acts as a molecular bridge within the heterotrimer by contacting the eWH and coiled-coil domains of RPC62, and the subcomplex is tethered to the Pol III core via a human-specific iron-sulfur cluster [PMID:26394183, PMID:33558764]. Heterozygous loss-of-function mutations in POLR3C cause impaired RNA Pol III-dependent cytosolic DNA sensing with defective interferon induction, conferring susceptibility to severe varicella zoster virus infection [PMID:28783042].\",\n  \"teleology\": [\n    {\n      \"year\": 1997,\n      \"claim\": \"Establishing that POLR3C resides in a Pol III-specific subcomplex required for promoter-dependent initiation resolved how Pol III distinguishes initiation from elongation at a subunit level.\",\n      \"evidence\": \"Immunopurification and reconstituted in vitro transcription with recombinant RPC32/RPC39/RPC62 subcomplex in human cell-free systems\",\n      \"pmids\": [\"9171375\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis of how the subcomplex contacts the Pol III core was unknown\",\n        \"Individual contributions of RPC32 versus RPC39/RPC62 to initiation were not separated\"\n      ]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Demonstrating that TFIIIC90 contacts RPC39 and RPC62 within the POLR3C-containing subcomplex provided a physical mechanism linking TFIIIC recognition of internal promoter elements to Pol III recruitment.\",\n      \"evidence\": \"Immunodepletion, reciprocal immunoprecipitation, and in vitro interaction assays\",\n      \"pmids\": [\"10523658\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether POLR3C itself makes direct contacts with TFIIIC was not tested\",\n        \"Stoichiometry of the TFIIIC–subcomplex interaction was not determined\"\n      ]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Solving the crystal structure of the RPC62–POLR3C binary complex revealed that POLR3C bridges multiple domains of RPC62 and exposes solvent-facing residues, defining its architectural role within the heterotrimer.\",\n      \"evidence\": \"X-ray crystallography of human RPC62–RPC32β complex fitted into Pol III EM density\",\n      \"pmids\": [\"26394183\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The structure lacked the third subunit RPC39, leaving the complete heterotrimer architecture unresolved\",\n        \"Functional validation of solvent-exposed interaction surfaces was not performed\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identifying heterozygous POLR3C mutations in patients with severe VZV infection, and rescuing the IFN-induction defect with wild-type allele, established a non-canonical role for Pol III-dependent DNA sensing in antiviral innate immunity.\",\n      \"evidence\": \"Primary patient leukocyte functional assays measuring IFN induction and viral replication, with lentiviral rescue\",\n      \"pmids\": [\"28783042\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether the immune phenotype reflects a specific POLR3C function beyond its role in the heterotrimer is unknown\",\n        \"Genotype–phenotype correlation across additional POLR3C variants remains unexplored\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Near-atomic cryo-EM structures of human Pol III revealed a human-specific iron-sulfur cluster that tethers the POLR3C-containing heterotrimer to the core, explaining a key structural divergence from yeast Pol III.\",\n      \"evidence\": \"Cryo-EM at 2.8–3.3 Å resolution of unbound and transcribing human Pol III\",\n      \"pmids\": [\"33558764\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Functional consequences of disrupting the iron-sulfur cluster have not been tested\",\n        \"How disease mutations mapped onto the structure alter initiation kinetics is unknown\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Functional conservation of the POLR3C ortholog in trypanosomatids confirmed its essential role in Pol III transcription across deeply divergent eukaryotes, while revealing lineage-specific differences such as the absence of a C31 ortholog.\",\n      \"evidence\": \"ChIP, RNAi knockdown, tandem affinity purification–mass spectrometry, and immunofluorescence in T. brucei and L. major\",\n      \"pmids\": [\"39523652\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Degree to which parasite-specific interactors are functionally equivalent to human heterotrimer components is unknown\",\n        \"Cross-species complementation has not been attempted\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The mechanism by which POLR3C specifically contributes to cytosolic DNA sensing — whether via a moonlighting function or solely through its role in the Pol III heterotrimer — and the structural basis of disease-causing mutations' effects on initiation kinetics remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No separation-of-function mutants distinguish POLR3C's transcription-initiation role from its innate immunity role\",\n        \"No kinetic or single-molecule studies on heterotrimer–promoter engagement exist\",\n        \"The functional significance of the iron-sulfur cluster for initiation versus complex stability has not been dissected\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0, 3, 5]},\n      {\"term_id\": \"GO:0140223\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [6]},\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [3, 5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 1, 3, 5, 6]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"complexes\": [\n      \"RNA Pol III holoenzyme\",\n      \"RPC32/RPC39/RPC62 heterotrimer\"\n    ],\n    \"partners\": [\n      \"POLR3F\",\n      \"POLR3D\",\n      \"POLR3A\",\n      \"PKP2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}