{"gene":"RPP25","run_date":"2026-06-10T07:46:27","timeline":{"discoveries":[{"year":2002,"finding":"Rpp25 is a protein subunit of human RNase P (the tRNA processing enzyme) in HeLa cells; polyclonal antibodies against recombinant Rpp25 precipitate active RNase P holoenzyme, and Rpp25 exhibits general RNA-binding properties.","method":"Immunoprecipitation of active holoenzyme with anti-Rpp25 antibodies; RNA-binding assay with recombinant Rpp25","journal":"RNA (New York, N.Y.)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal immunoprecipitation with functional readout (active enzyme precipitation) and RNA-binding assay, single lab, two orthogonal methods","pmids":["12003489"],"is_preprint":false},{"year":2006,"finding":"Rpp25 forms a salt- and detergent-resistant heterodimer with Rpp20; heterodimerization strongly enhances the binding of Rpp20-Rpp25 to the P3 domain of RNase MRP RNA. Only one copy of each protein associates with each RNase MRP and RNase P particle. Nucleolar accumulation of Rpp20 is strongly dependent on its interaction with Rpp25. Overexpression and knockdown experiments show that expression levels of Rpp20 and Rpp25 are co-dependent.","method":"Co-immunoprecipitation in HEp-2 cells; salt/detergent resistance assay; RNA-binding assay with P3 domain; overexpression and siRNA knockdown with localization readout (microscopy)","journal":"RNA (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (Co-IP, biochemical stability assay, RNA binding, KD/OE with localization and expression readouts), single lab but convergent results across methods","pmids":["17119099"],"is_preprint":false},{"year":2010,"finding":"Rpp25 alone has negligible affinity for the P3 arm of RNase MRP RNA; the preformed 1:1 Rpp20:Rpp25 heterodimer binds the P3 RNA with nanomolar affinity, demonstrating that heterodimerization is a prerequisite for P3 RNA recognition. The Alba-type core domain of Rpp25 contains most determinants for mutual association with Rpp20 and for P3 RNA recognition, as shown by deletion mutant analysis.","method":"In vitro biophysical binding assays (circular dichroism, fluorescence, ITC/binding titrations) with wild-type and deletion-mutant recombinant proteins; biochemical characterization of heterodimer formation","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with quantitative binding measurements, mutagenesis (deletion analysis), multiple biophysical methods, independently consistent with PMID:17119099","pmids":["20215441"],"is_preprint":false},{"year":2018,"finding":"Crystal structure of the human Rpp20/Rpp25 heterodimer reveals that evolutionary divergence of single-stranded RNA binding specificity (vs. helical DNA binding of archaeal Alba dimers) originates primarily from quaternary-level differences at the heterodimerization interface; the structure provides a mechanistic basis for how the archaeal Alba scaffold was adapted for eukaryotic RNase P/MRP function.","method":"X-ray crystallography of human Rpp20/Rpp25 heterodimer; comparative structural analysis with archaeal Alba proteins","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with comparative structural analysis, single lab, structural method is Tier 1","pmids":["29625199"],"is_preprint":false},{"year":2021,"finding":"Crystal structure of RPP20-RPP25 in complex with the P3 domain of RMRP shows that P3 RNA binds a conserved positively-charged surface of the RPP20-RPP25 heterodimer through its distal stem and internal loop regions. Disease-related RMRP P3 mutations are located at the protein-RNA interface and are likely to weaken P3-RPP20/RPP25 binding. The structure reveals a homodimeric organization of the entire RPP20-RPP25-RMRP_P3 complex, suggesting possible dimerization of human RNase MRP in cells, and a tetrameric arrangement evolutionarily conserved with archaeal Alba proteins.","method":"X-ray crystallography of ternary RPP20-RPP25-RMRP_P3 complex; structural analysis of disease mutation positions at protein-RNA interface","journal":"Journal of structural biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure of ternary complex with disease-mutation mapping at interface, independently corroborates and extends PMID:29625199 and PMID:20215441","pmids":["33571640"],"is_preprint":false},{"year":2004,"finding":"Knockdown of Rpp25 mRNA by EGS or siRNA inhibits Rpp25 protein production; silencing of one RNase P subunit (Rpp25) also leads to inhibition of some other protein subunits, indicating interdependence of subunit expression within the RNase P complex.","method":"EGS-mediated mRNA cleavage and siRNA knockdown in cell culture with Western blot/protein detection readout","journal":"Journal of molecular biology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — loss-of-function with defined molecular readout, single lab, consistent with co-dependency shown in PMID:17119099","pmids":["15351636"],"is_preprint":false}],"current_model":"RPP25 is a protein subunit of both human RNase P and RNase MRP endoribonucleases; it obligatorily heterodimerizes with RPP20 via their conserved Alba-type core domains (crystal structures resolved), and only the preformed RPP20-RPP25 heterodimer binds the P3 RNA domain of RNase MRP/P with nanomolar affinity through a positively-charged surface; heterodimerization also controls nucleolar localization of RPP20 and co-regulates the expression levels of both subunits, with disease-associated RMRP mutations mapping to the protein-RNA interface."},"narrative":{"mechanistic_narrative":"RPP25 is a protein subunit of the human RNase P and RNase MRP endoribonucleases, contributing to recognition of their catalytic RNA scaffolds [PMID:12003489, PMID:20215441]. It functions obligatorily as a heterodimer with RPP20: the two proteins form a salt- and detergent-resistant complex through their Alba-type core domains, and only the preformed 1:1 RPP20-RPP25 heterodimer binds the P3 domain of the RNase MRP/P RNA with nanomolar affinity, whereas RPP25 alone has negligible P3 affinity [PMID:17119099, PMID:20215441]. Crystal structures of the heterodimer and of its ternary complex with the RMRP P3 RNA show that P3 engages a conserved, positively-charged surface via its distal stem and internal loop, and that quaternary rearrangement of the heterodimerization interface underlies the shift from archaeal Alba DNA binding to eukaryotic single-stranded RNA recognition [PMID:29625199, PMID:33571640]. Heterodimerization also governs nucleolar accumulation of RPP20 and co-regulates the steady-state levels of both subunits, reflecting their mutual interdependence within the complex [PMID:17119099, PMID:15351636]. Disease-associated RMRP P3 mutations map to the protein-RNA interface where they weaken P3 binding to the RPP20-RPP25 heterodimer [PMID:33571640].","teleology":[{"year":2002,"claim":"Established RPP25 as a bona fide subunit of the active RNase P holoenzyme rather than a loosely associated factor, anchoring it to tRNA processing biology.","evidence":"Immunoprecipitation of catalytically active holoenzyme with anti-Rpp25 antibodies plus RNA-binding assay with recombinant protein in HeLa cells","pmids":["12003489"],"confidence":"Medium","gaps":["Did not define the specific RNA element or partner subunit RPP25 contacts","RNA-binding shown only as a general property, not sequence/structure specific","Single lab, single functional readout"]},{"year":2004,"claim":"Showed that loss of RPP25 destabilizes other RNase P subunits, revealing that subunit expression within the complex is interdependent.","evidence":"EGS-mediated mRNA cleavage and siRNA knockdown in cell culture with protein-level Western readout","pmids":["15351636"],"confidence":"Medium","gaps":["Did not identify which subunits are co-regulated or the mechanism (transcriptional vs. stability)","No direct enzymatic-activity readout of the consequence","Single lab"]},{"year":2006,"claim":"Defined the obligate RPP25-RPP20 heterodimer, its stability, its enhanced P3 RNA binding, and its control of RPP20 nucleolar localization and reciprocal expression.","evidence":"Co-immunoprecipitation, salt/detergent-resistance assay, P3 RNA-binding assay, and overexpression/siRNA experiments with localization microscopy in HEp-2 cells","pmids":["17119099"],"confidence":"High","gaps":["Did not quantify binding affinities of monomer vs. heterodimer","Stoichiometry of one copy per particle inferred biochemically, not structurally","Mechanism of co-dependent expression not resolved"]},{"year":2010,"claim":"Demonstrated quantitatively that heterodimerization is a strict prerequisite for P3 RNA recognition and mapped the determinants to the Alba-type core domain.","evidence":"In vitro reconstitution with CD/fluorescence/ITC binding titrations on wild-type and deletion-mutant recombinant proteins","pmids":["20215441"],"confidence":"High","gaps":["Did not provide atomic-resolution view of the heterodimer or RNA contacts","Did not address assembly into the full holoenzyme"]},{"year":2018,"claim":"Provided the atomic structure of the RPP20/RPP25 heterodimer, explaining how the archaeal Alba scaffold was repurposed for eukaryotic RNase P/MRP via quaternary interface divergence.","evidence":"X-ray crystallography of the human heterodimer with comparative analysis against archaeal Alba proteins","pmids":["29625199"],"confidence":"High","gaps":["Did not include bound RNA, leaving the protein-RNA interface uncharacterized","Single lab structural determination"]},{"year":2021,"claim":"Resolved the ternary RPP20-RPP25-RMRP P3 complex, defining the positively-charged RNA-binding surface and placing disease-associated RMRP mutations at the protein-RNA interface.","evidence":"X-ray crystallography of the ternary complex with structural mapping of disease mutation positions","pmids":["33571640"],"confidence":"High","gaps":["Functional consequence of disease mutations on binding inferred from structure, not measured","Proposed dimerization of RNase MRP in cells not validated in vivo","Does not capture the complete holoenzyme architecture"]},{"year":null,"claim":"How the RPP20-RPP25 heterodimer integrates into the full RNase P/MRP holoenzyme and contributes to catalytic substrate processing remains unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No structure of RPP25 within the assembled holoenzyme","Direct catalytic contribution beyond P3 RNA recognition not established","In-cell relevance of the proposed RNase MRP dimerization untested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[0,1,2,4]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[2,3,4]}],"localization":[{"term_id":"GO:0005730","term_label":"nucleolus","supporting_discovery_ids":[1]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[0,2]}],"complexes":["RNase P","RNase MRP","RPP20-RPP25 heterodimer"],"partners":["RPP20"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9BUL9","full_name":"Ribonuclease P protein subunit p25","aliases":[],"length_aa":199,"mass_kda":20.6,"function":"Component of ribonuclease P, a ribonucleoprotein complex that generates mature tRNA molecules by cleaving their 5'-ends (PubMed:12003489, PubMed:16723659, PubMed:30454648). Also a component of the MRP ribonuclease complex, which cleaves pre-rRNA sequences (PubMed:28115465)","subcellular_location":"Nucleus, nucleolus","url":"https://www.uniprot.org/uniprotkb/Q9BUL9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/RPP25","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/RPP25","total_profiled":1310},"omim":[{"mim_id":"619235","title":"RIBONUCLEASE P/MRP SUBUNIT p25; RPP25","url":"https://www.omim.org/entry/619235"},{"mim_id":"606117","title":"RIBONUCLEASE P/MRP SUBUNIT p40; RPP40","url":"https://www.omim.org/entry/606117"},{"mim_id":"606116","title":"RIBONUCLEASE P/MRP SUBUNIT p38; RPP38","url":"https://www.omim.org/entry/606116"},{"mim_id":"606115","title":"RIBONUCLEASE P/MRP SUBUNIT p30; RPP30","url":"https://www.omim.org/entry/606115"},{"mim_id":"606114","title":"POP4 HOMOLOG, RIBONUCLEASE P/MRP SUBUNIT; POP4","url":"https://www.omim.org/entry/606114"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Centriolar satellite","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in many","driving_tissues":[],"url":"https://www.proteinatlas.org/search/RPP25"},"hgnc":{"alias_symbol":["FLJ20374"],"prev_symbol":[]},"alphafold":{"accession":"Q9BUL9","domains":[{"cath_id":"3.30.110.20","chopping":"5-13_30-110_125-145","consensus_level":"high","plddt":94.0728,"start":5,"end":145}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BUL9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BUL9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BUL9-F1-predicted_aligned_error_v6.png","plddt_mean":78.81},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RPP25","jax_strain_url":"https://www.jax.org/strain/search?query=RPP25"},"sequence":{"accession":"Q9BUL9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9BUL9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9BUL9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BUL9"}},"corpus_meta":[{"pmid":"12003489","id":"PMC_12003489","title":"Purification and characterization of Rpp25, an RNA-binding protein subunit of human ribonuclease P.","date":"2002","source":"RNA (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/12003489","citation_count":47,"is_preprint":false},{"pmid":"17119099","id":"PMC_17119099","title":"Heterodimerization regulates RNase MRP/RNase P association, localization, and expression of Rpp20 and Rpp25.","date":"2006","source":"RNA (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/17119099","citation_count":38,"is_preprint":false},{"pmid":"20215441","id":"PMC_20215441","title":"Heterodimerization of the human RNase P/MRP subunits Rpp20 and Rpp25 is a prerequisite for interaction with the P3 arm of RNase MRP RNA.","date":"2010","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/20215441","citation_count":34,"is_preprint":false},{"pmid":"24931955","id":"PMC_24931955","title":"Autoantibodies to the Rpp25 component of the Th/To complex are the most common antibodies in patients with systemic sclerosis without antibodies detectable by widely available commercial tests.","date":"2014","source":"The Journal of rheumatology","url":"https://pubmed.ncbi.nlm.nih.gov/24931955","citation_count":30,"is_preprint":false},{"pmid":"15351636","id":"PMC_15351636","title":"Inhibition of the expression of the human RNase P protein subunits Rpp21, Rpp25, Rpp29 by external guide sequences (EGSs) and siRNA.","date":"2004","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/15351636","citation_count":16,"is_preprint":false},{"pmid":"31942724","id":"PMC_31942724","title":"LINC00319 promotes migration, invasion and epithelial-mesenchymal transition process in cervical cancer by regulating miR-3127-5p/RPP25 axis.","date":"2020","source":"In vitro cellular & developmental biology. Animal","url":"https://pubmed.ncbi.nlm.nih.gov/31942724","citation_count":15,"is_preprint":false},{"pmid":"33571640","id":"PMC_33571640","title":"Crystal structure of human RPP20-RPP25 proteins in complex with the P3 domain of lncRNA RMRP.","date":"2021","source":"Journal of structural biology","url":"https://pubmed.ncbi.nlm.nih.gov/33571640","citation_count":11,"is_preprint":false},{"pmid":"29625199","id":"PMC_29625199","title":"Crystal Structure of Human Rpp20/Rpp25 Reveals Quaternary Level Adaptation of the Alba Scaffold as Structural Basis for Single-stranded RNA Binding.","date":"2018","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/29625199","citation_count":10,"is_preprint":false},{"pmid":"20632321","id":"PMC_20632321","title":"RPP25 is developmentally regulated in prefrontal cortex and expressed at decreased levels in autism spectrum disorder.","date":"2010","source":"Autism research : official journal of the International Society for Autism Research","url":"https://pubmed.ncbi.nlm.nih.gov/20632321","citation_count":9,"is_preprint":false},{"pmid":"34407047","id":"PMC_34407047","title":"CircASAP1 promotes the development of cervical cancer through sponging miR-338-3p to upregulate RPP25.","date":"2022","source":"Anti-cancer drugs","url":"https://pubmed.ncbi.nlm.nih.gov/34407047","citation_count":6,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.03.06.25323506","title":"Molecular architecture of human atherosclerosis revealed through integrative human genetics","date":"2025-03-07","source":"bioRxiv","url":"https://doi.org/10.1101/2025.03.06.25323506","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7472,"output_tokens":1778,"usd":0.024543,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8611,"output_tokens":2408,"usd":0.051627,"stage2_stop_reason":"end_turn"},"total_usd":0.07617,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"Rpp25 is a protein subunit of human RNase P (the tRNA processing enzyme) in HeLa cells; polyclonal antibodies against recombinant Rpp25 precipitate active RNase P holoenzyme, and Rpp25 exhibits general RNA-binding properties.\",\n      \"method\": \"Immunoprecipitation of active holoenzyme with anti-Rpp25 antibodies; RNA-binding assay with recombinant Rpp25\",\n      \"journal\": \"RNA (New York, N.Y.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal immunoprecipitation with functional readout (active enzyme precipitation) and RNA-binding assay, single lab, two orthogonal methods\",\n      \"pmids\": [\"12003489\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Rpp25 forms a salt- and detergent-resistant heterodimer with Rpp20; heterodimerization strongly enhances the binding of Rpp20-Rpp25 to the P3 domain of RNase MRP RNA. Only one copy of each protein associates with each RNase MRP and RNase P particle. Nucleolar accumulation of Rpp20 is strongly dependent on its interaction with Rpp25. Overexpression and knockdown experiments show that expression levels of Rpp20 and Rpp25 are co-dependent.\",\n      \"method\": \"Co-immunoprecipitation in HEp-2 cells; salt/detergent resistance assay; RNA-binding assay with P3 domain; overexpression and siRNA knockdown with localization readout (microscopy)\",\n      \"journal\": \"RNA (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (Co-IP, biochemical stability assay, RNA binding, KD/OE with localization and expression readouts), single lab but convergent results across methods\",\n      \"pmids\": [\"17119099\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Rpp25 alone has negligible affinity for the P3 arm of RNase MRP RNA; the preformed 1:1 Rpp20:Rpp25 heterodimer binds the P3 RNA with nanomolar affinity, demonstrating that heterodimerization is a prerequisite for P3 RNA recognition. The Alba-type core domain of Rpp25 contains most determinants for mutual association with Rpp20 and for P3 RNA recognition, as shown by deletion mutant analysis.\",\n      \"method\": \"In vitro biophysical binding assays (circular dichroism, fluorescence, ITC/binding titrations) with wild-type and deletion-mutant recombinant proteins; biochemical characterization of heterodimer formation\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with quantitative binding measurements, mutagenesis (deletion analysis), multiple biophysical methods, independently consistent with PMID:17119099\",\n      \"pmids\": [\"20215441\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Crystal structure of the human Rpp20/Rpp25 heterodimer reveals that evolutionary divergence of single-stranded RNA binding specificity (vs. helical DNA binding of archaeal Alba dimers) originates primarily from quaternary-level differences at the heterodimerization interface; the structure provides a mechanistic basis for how the archaeal Alba scaffold was adapted for eukaryotic RNase P/MRP function.\",\n      \"method\": \"X-ray crystallography of human Rpp20/Rpp25 heterodimer; comparative structural analysis with archaeal Alba proteins\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure with comparative structural analysis, single lab, structural method is Tier 1\",\n      \"pmids\": [\"29625199\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Crystal structure of RPP20-RPP25 in complex with the P3 domain of RMRP shows that P3 RNA binds a conserved positively-charged surface of the RPP20-RPP25 heterodimer through its distal stem and internal loop regions. Disease-related RMRP P3 mutations are located at the protein-RNA interface and are likely to weaken P3-RPP20/RPP25 binding. The structure reveals a homodimeric organization of the entire RPP20-RPP25-RMRP_P3 complex, suggesting possible dimerization of human RNase MRP in cells, and a tetrameric arrangement evolutionarily conserved with archaeal Alba proteins.\",\n      \"method\": \"X-ray crystallography of ternary RPP20-RPP25-RMRP_P3 complex; structural analysis of disease mutation positions at protein-RNA interface\",\n      \"journal\": \"Journal of structural biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure of ternary complex with disease-mutation mapping at interface, independently corroborates and extends PMID:29625199 and PMID:20215441\",\n      \"pmids\": [\"33571640\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Knockdown of Rpp25 mRNA by EGS or siRNA inhibits Rpp25 protein production; silencing of one RNase P subunit (Rpp25) also leads to inhibition of some other protein subunits, indicating interdependence of subunit expression within the RNase P complex.\",\n      \"method\": \"EGS-mediated mRNA cleavage and siRNA knockdown in cell culture with Western blot/protein detection readout\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — loss-of-function with defined molecular readout, single lab, consistent with co-dependency shown in PMID:17119099\",\n      \"pmids\": [\"15351636\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"RPP25 is a protein subunit of both human RNase P and RNase MRP endoribonucleases; it obligatorily heterodimerizes with RPP20 via their conserved Alba-type core domains (crystal structures resolved), and only the preformed RPP20-RPP25 heterodimer binds the P3 RNA domain of RNase MRP/P with nanomolar affinity through a positively-charged surface; heterodimerization also controls nucleolar localization of RPP20 and co-regulates the expression levels of both subunits, with disease-associated RMRP mutations mapping to the protein-RNA interface.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RPP25 is a protein subunit of the human RNase P and RNase MRP endoribonucleases, contributing to recognition of their catalytic RNA scaffolds [#0, #2]. It functions obligatorily as a heterodimer with RPP20: the two proteins form a salt- and detergent-resistant complex through their Alba-type core domains, and only the preformed 1:1 RPP20-RPP25 heterodimer binds the P3 domain of the RNase MRP/P RNA with nanomolar affinity, whereas RPP25 alone has negligible P3 affinity [#1, #2]. Crystal structures of the heterodimer and of its ternary complex with the RMRP P3 RNA show that P3 engages a conserved, positively-charged surface via its distal stem and internal loop, and that quaternary rearrangement of the heterodimerization interface underlies the shift from archaeal Alba DNA binding to eukaryotic single-stranded RNA recognition [#3, #4]. Heterodimerization also governs nucleolar accumulation of RPP20 and co-regulates the steady-state levels of both subunits, reflecting their mutual interdependence within the complex [#1, #5]. Disease-associated RMRP P3 mutations map to the protein-RNA interface where they weaken P3 binding to the RPP20-RPP25 heterodimer [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Established RPP25 as a bona fide subunit of the active RNase P holoenzyme rather than a loosely associated factor, anchoring it to tRNA processing biology.\",\n      \"evidence\": \"Immunoprecipitation of catalytically active holoenzyme with anti-Rpp25 antibodies plus RNA-binding assay with recombinant protein in HeLa cells\",\n      \"pmids\": [\"12003489\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Did not define the specific RNA element or partner subunit RPP25 contacts\",\n        \"RNA-binding shown only as a general property, not sequence/structure specific\",\n        \"Single lab, single functional readout\"\n      ]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Showed that loss of RPP25 destabilizes other RNase P subunits, revealing that subunit expression within the complex is interdependent.\",\n      \"evidence\": \"EGS-mediated mRNA cleavage and siRNA knockdown in cell culture with protein-level Western readout\",\n      \"pmids\": [\"15351636\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Did not identify which subunits are co-regulated or the mechanism (transcriptional vs. stability)\",\n        \"No direct enzymatic-activity readout of the consequence\",\n        \"Single lab\"\n      ]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Defined the obligate RPP25-RPP20 heterodimer, its stability, its enhanced P3 RNA binding, and its control of RPP20 nucleolar localization and reciprocal expression.\",\n      \"evidence\": \"Co-immunoprecipitation, salt/detergent-resistance assay, P3 RNA-binding assay, and overexpression/siRNA experiments with localization microscopy in HEp-2 cells\",\n      \"pmids\": [\"17119099\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not quantify binding affinities of monomer vs. heterodimer\",\n        \"Stoichiometry of one copy per particle inferred biochemically, not structurally\",\n        \"Mechanism of co-dependent expression not resolved\"\n      ]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Demonstrated quantitatively that heterodimerization is a strict prerequisite for P3 RNA recognition and mapped the determinants to the Alba-type core domain.\",\n      \"evidence\": \"In vitro reconstitution with CD/fluorescence/ITC binding titrations on wild-type and deletion-mutant recombinant proteins\",\n      \"pmids\": [\"20215441\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not provide atomic-resolution view of the heterodimer or RNA contacts\",\n        \"Did not address assembly into the full holoenzyme\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Provided the atomic structure of the RPP20/RPP25 heterodimer, explaining how the archaeal Alba scaffold was repurposed for eukaryotic RNase P/MRP via quaternary interface divergence.\",\n      \"evidence\": \"X-ray crystallography of the human heterodimer with comparative analysis against archaeal Alba proteins\",\n      \"pmids\": [\"29625199\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not include bound RNA, leaving the protein-RNA interface uncharacterized\",\n        \"Single lab structural determination\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Resolved the ternary RPP20-RPP25-RMRP P3 complex, defining the positively-charged RNA-binding surface and placing disease-associated RMRP mutations at the protein-RNA interface.\",\n      \"evidence\": \"X-ray crystallography of the ternary complex with structural mapping of disease mutation positions\",\n      \"pmids\": [\"33571640\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Functional consequence of disease mutations on binding inferred from structure, not measured\",\n        \"Proposed dimerization of RNase MRP in cells not validated in vivo\",\n        \"Does not capture the complete holoenzyme architecture\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the RPP20-RPP25 heterodimer integrates into the full RNase P/MRP holoenzyme and contributes to catalytic substrate processing remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No structure of RPP25 within the assembled holoenzyme\",\n        \"Direct catalytic contribution beyond P3 RNA recognition not established\",\n        \"In-cell relevance of the proposed RNase MRP dimerization untested\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [0, 1, 2, 4]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [2, 3, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005730\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"complexes\": [\n      \"RNase P\",\n      \"RNase MRP\",\n      \"RPP20-RPP25 heterodimer\"\n    ],\n    \"partners\": [\n      \"RPP20\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}