{"gene":"TAF13","run_date":"2026-06-10T10:51:54","timeline":{"discoveries":[{"year":2017,"finding":"TAF11 and TAF13 form a ternary complex with TBP via their histone fold (HF) domains. TAF11/TAF13 competes with TATA-box DNA for binding to the DNA-binding surface of TBP, and also competes with the N-terminal domain of TAF1 (previously implicated in TATA-box mimicry). A highly conserved C-terminal TBP-interaction domain (CTID) in TAF13 is essential for supporting cell growth.","method":"Crystal structure determination, cross-linking mass spectrometry (CLMS), biochemical binding assays, mutagenesis","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 / Strong — integrative structural study combining crystal coordinates, CLMS, and biochemical validation with mutagenesis in a single rigorous study","pmids":["29111974"],"is_preprint":false},{"year":2017,"finding":"Pathogenic missense variants in TAF13 (p.Met40Lys and p.Leu31His) impair formation of the TAF13-TAF11 histone-like heterodimer, which is required for recruitment of TAF11/TAF13 into TFIID. This disruption is associated with intellectual disability and microcephaly. TAF13 knockdown in neuroblastoma cells leads to deregulation of genes related to neuronal and skeletal functions and those containing E-box motifs.","method":"Co-immunoprecipitation in HeLa cells, molecular modeling, RNA sequencing upon TAF13 knockdown","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP with disease variants plus transcriptomic functional readout, replicated across two independent families","pmids":["28257693"],"is_preprint":false},{"year":2003,"finding":"In yeast TFIID, TAF11 and TAF13 provide critical functional contacts with TBP during preinitiation complex (PIC) assembly, as revealed by temperature-sensitive mutant analysis; loss of TAF13 function reduces TBP recruitment to promoters.","method":"Temperature-sensitive yeast mutants, genome-wide expression profiling, chromatin immunoprecipitation for PIC assembly","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with temperature-sensitive alleles, ChIP-based PIC assembly assays, replicated across all 13 essential TAF mutants providing strong internal controls","pmids":["12840001"],"is_preprint":false},{"year":1999,"finding":"Specific amino acids in the alpha2-helix of hTAFII28 (TAF13's heterodimer partner) mediate interaction with TAFII18 (TAF13) at the hydrophobic interface; mutation of these residues abolishes the hTAFII28-TAFII18 interaction and disrupts synergistic transcriptional activation with TBP.","method":"Mutagenesis of histone fold domain residues, mammalian cell transcription assays with altered-specificity TBP mutant","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — mutagenesis-based in vivo transcription assay, single lab, establishes the hydrophobic interface between TAF13 and TAF11 but indirect (TAF13 inferred as the binding partner)","pmids":["10373554"],"is_preprint":false},{"year":1996,"finding":"Yeast TAF19 (FUN81), the homologue of human TAFII18/TAF13, co-immunoprecipitates with TBP and is present in complexes containing the TAFII130 subunit, establishing it as a bona fide component of the TFIID complex.","method":"Coimmunoprecipitation, sequence homology, essential gene viability assay in yeast","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP demonstrating TBP and TFIID association in yeast, confirmed across multiple TAF subunits in same study","pmids":["8962109"],"is_preprint":false},{"year":1998,"finding":"Human TAFII18 (TAF13) is not associated in vivo with human TBP/TFIID or with a TFIID-related TBP-free TAF complex, establishing that it is not a component of the human STAGA complex (which contains the related hSPT3).","method":"Native complex immunoprecipitation and Western blotting from human cell extracts","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — negative result from Co-IP fractionation, single lab; establishes TAFII18/TAF13 is excluded from STAGA but does not exclude TFIID membership","pmids":["9726987"],"is_preprint":false},{"year":2017,"finding":"Rapid degron-dependent depletion of yeast Taf13 strongly reduces nascent transcription of nearly all RNA Pol II-transcribed genes, demonstrating that TAF13 is broadly required for TFIID-dependent transcription across gene classes (TATA and TATA-less, Taf1-enriched and Taf1-depleted).","method":"Auxin-inducible degron depletion, nascent transcription measurement (NET-seq/GRO-seq type assay), genome-wide","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — acute protein depletion with nascent transcript measurement, replicated across multiple TAF subunits, genome-wide readout","pmids":["28918900"],"is_preprint":false},{"year":2024,"finding":"Taf13 knockout in mice causes embryonic lethality after implantation; Taf13-null embryos successfully implant and form egg-cylinder stages but fail to initiate gastrulation. TAF13 deficiency leads to depletion of pluripotency factors OCT4, NANOG, and SOX2, demonstrating an essential role in maintaining pluripotency.","method":"Conditional/constitutive mouse knockout, immunofluorescence for pluripotency markers, transcriptomic analysis","journal":"Developmental biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean knockout with defined phenotypic readout (gastrulation failure, pluripotency factor depletion), protein-level validation of pluripotency markers","pmids":["38593904"],"is_preprint":false},{"year":2025,"finding":"In mouse embryonic stem cells, Taf13 loss had little effect on overall TFIID integrity and caused only a mild reduction of TBP promoter recruitment, but led to altered PIC formation and globally reduced RNA Pol II recruitment. Thus, the TAF11-TAF13 heterodimer is not essential for TBP/TFIID promoter recruitment, revealing plasticity in PIC assembly pathways.","method":"Gene inactivation in mouse ESCs, ChIP-seq for TBP and Pol II, cryo-EM-informed genetic analysis","journal":"iScience","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean genetic loss-of-function with ChIP-seq readout for TBP and Pol II occupancy genome-wide, directly testing cryo-EM model prediction","pmids":["40491483"],"is_preprint":false},{"year":2022,"finding":"In yeast, depletion of Taf13 suppresses the overactivation of TFIID-dependent genes caused by separation of Mediator core and tail modules, placing TAF13/TFIID downstream of Mediator core-tail integrity in the transcriptional regulatory hierarchy.","method":"Genetic epistasis in yeast (double mutant: Taf13 depletion × Med16 deletion), mRNA expression profiling","journal":"G3 (Bethesda, Md.)","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — genetic epistasis with expression readout, single lab, effect on TFIID genomic occupancy not fully resolved","pmids":["36331351"],"is_preprint":false}],"current_model":"TAF13 (TAFII18) is a core subunit of the general transcription factor TFIID that forms a histone fold heterodimer with TAF11; the TAF11/TAF13 complex binds to the DNA-binding surface of TBP, competing with both TATA-box DNA and the TAF1 N-terminal domain, thereby regulating TFIID assembly and PIC formation—though TAF11/TAF13 is not strictly required for TBP promoter recruitment, its loss reduces RNA Pol II recruitment and is essential for gastrulation and maintenance of pluripotency in mammals, with disease-causing variants in its TAF11-interaction interface causing intellectual disability and microcephaly."},"narrative":{"mechanistic_narrative":"TAF13 (TAFII18) is a core histone-fold subunit of the general transcription factor TFIID that governs RNA polymerase II preinitiation complex (PIC) assembly across the genome [PMID:29111974, PMID:28918900]. It pairs with TAF11 through reciprocal histone-fold domains to form a heterodimer, and this heterodimer engages the DNA-binding surface of TBP, competing with both TATA-box DNA and the TATA-mimicking N-terminal domain of TAF1; a conserved C-terminal TBP-interaction domain in TAF13 is required for cell growth [PMID:29111974]. TAF13 is a bona fide TFIID component that provides functional contacts with TBP during PIC assembly, and its acute loss broadly reduces nascent transcription of nearly all Pol II genes regardless of TATA-box status or TAF1 enrichment [PMID:12840001, PMID:28918900]. Genetically, TAF13/TFIID acts downstream of Mediator core-tail integrity in the transcriptional regulatory hierarchy [PMID:36331351]. In mammals TAF13 is essential for development: its knockout blocks gastrulation and depletes the pluripotency factors OCT4, NANOG, and SOX2 in mouse embryos [PMID:38593904]. Notably, loss of the TAF11-TAF13 heterodimer in mouse ESCs leaves overall TFIID integrity and TBP promoter recruitment largely intact yet still impairs PIC formation and globally reduces Pol II recruitment, revealing plasticity in PIC assembly pathways [PMID:40491483]. Pathogenic missense variants in the TAF13 interface that forms the TAF11 heterodimer cause intellectual disability and microcephaly [PMID:28257693].","teleology":[{"year":1996,"claim":"Established that the human TAFII18/TAF13 homologue is a genuine constituent of TFIID rather than an isolated factor, answering whether this small subunit belongs to the TBP-containing complex.","evidence":"Co-immunoprecipitation with TBP and the TAFII130 subunit in yeast plus essential-gene viability assay","pmids":["8962109"],"confidence":"Medium","gaps":["Did not define how TAF13 contacts TBP","Membership demonstrated in yeast, not yet structurally resolved"]},{"year":1998,"claim":"Delimited the complex membership of TAFII18/TAF13 by showing it is excluded from the TBP-free STAGA complex, distinguishing it from related histone-fold subunits.","evidence":"Native complex immunoprecipitation and Western blotting from human cell extracts","pmids":["9726987"],"confidence":"Medium","gaps":["Negative result from a single lab","Does not resolve TAF13's quantitative contribution to TFIID"]},{"year":1999,"claim":"Mapped the physical interface mediating the histone-fold heterodimer, showing specific alpha2-helix residues drive partner binding and synergistic activation with TBP.","evidence":"Mutagenesis of histone-fold residues and mammalian transcription assays with an altered-specificity TBP mutant","pmids":["10373554"],"confidence":"Medium","gaps":["TAF13 inferred as binding partner rather than directly assayed","Single-lab in vivo transcription readout"]},{"year":2003,"claim":"Demonstrated that TAF11 and TAF13 provide functionally critical contacts with TBP during PIC assembly, linking the subunit to promoter recruitment in vivo.","evidence":"Temperature-sensitive yeast TAF mutants with genome-wide expression profiling and ChIP for PIC assembly","pmids":["12840001"],"confidence":"High","gaps":["Temperature-sensitive alleles may produce indirect effects","Structural basis of TBP contact not defined"]},{"year":2017,"claim":"Resolved the structural logic of TAF13 function, showing the TAF11/TAF13 heterodimer binds the TBP DNA-binding surface in competition with TATA DNA and the TAF1 N-terminal domain, and defined a conserved CTID essential for growth.","evidence":"Crystal structure, cross-linking mass spectrometry, biochemical binding assays and mutagenesis","pmids":["29111974"],"confidence":"High","gaps":["Functional consequence of TBP-surface competition for in vivo PIC dynamics not fully defined","Does not resolve order of events during PIC assembly"]},{"year":2017,"claim":"Connected TAF13 to human disease by showing missense variants that disrupt the TAF11-TAF13 heterodimer and TFIID incorporation cause intellectual disability and microcephaly.","evidence":"Co-immunoprecipitation with disease variants in HeLa cells, molecular modeling, and RNA-seq after TAF13 knockdown across two families","pmids":["28257693"],"confidence":"High","gaps":["Causal chain from transcriptional deregulation to neurodevelopmental phenotype not established","E-box gene deregulation mechanism unresolved"]},{"year":2017,"claim":"Established that TAF13 is broadly required for TFIID-dependent transcription, showing acute depletion reduces nascent transcription of nearly all Pol II genes regardless of promoter class.","evidence":"Auxin-inducible degron depletion of yeast Taf13 with genome-wide nascent transcript measurement","pmids":["28918900"],"confidence":"High","gaps":["Does not distinguish direct versus indirect effects on individual genes","Mechanism downstream of TBP contact not resolved"]},{"year":2022,"claim":"Positioned TAF13/TFIID downstream of Mediator core-tail integrity, ordering it within the transcriptional regulatory hierarchy.","evidence":"Genetic epistasis in yeast (Taf13 depletion x Med16 deletion) with mRNA expression profiling","pmids":["36331351"],"confidence":"Medium","gaps":["Effect on TFIID genomic occupancy not fully resolved","Single-lab epistasis"]},{"year":2024,"claim":"Defined an essential mammalian developmental role, showing Taf13 is required for gastrulation and maintenance of the OCT4/NANOG/SOX2 pluripotency network.","evidence":"Mouse knockout with immunofluorescence for pluripotency markers and transcriptomic analysis","pmids":["38593904"],"confidence":"High","gaps":["Whether pluripotency factor loss is a direct transcriptional effect not established","Stage-specific requirement before implantation untested"]},{"year":2025,"claim":"Revealed plasticity in PIC assembly, showing the TAF11-TAF13 heterodimer is dispensable for TBP/TFIID promoter recruitment yet still required for normal PIC formation and Pol II recruitment.","evidence":"Gene inactivation in mouse ESCs with ChIP-seq for TBP and Pol II, interpreted against cryo-EM models","pmids":["40491483"],"confidence":"High","gaps":["Alternative PIC assembly pathway not molecularly defined","Reconciliation with broad transcriptional requirement seen in yeast incomplete"]},{"year":null,"claim":"How TAF13's structural competition with TATA DNA and TAF1 is dynamically resolved during PIC assembly, and how this links to its developmental and disease functions, remains unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No time-resolved model of PIC assembly steps requiring TAF11/TAF13","Mechanism linking transcriptional defects to pluripotency loss and neurodevelopmental disease unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,2,6]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[0]},{"term_id":"GO:0042393","term_label":"histone binding","supporting_discovery_ids":[0,3]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,4]}],"pathway":[{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[2,6]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[7]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[1]}],"complexes":["TFIID"],"partners":["TAF11","TBP","TAF1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q15543","full_name":"Transcription initiation factor TFIID subunit 13","aliases":["Transcription initiation factor TFIID 18 kDa subunit","TAF(II)18","TAFII-18","TAFII18"],"length_aa":124,"mass_kda":14.3,"function":"The TFIID basal transcription factor complex plays a major role in the initiation of RNA polymerase II (Pol II)-dependent transcription (PubMed:33795473, PubMed:9695952). TFIID recognizes and binds promoters via its subunit TBP, a TATA-box-binding protein, and promotes assembly of the pre-initiation complex (PIC) (PubMed:33795473). The TFIID complex consists of TBP and TBP-associated factors (TAFs), including TAF1, TAF2, TAF3, TAF4, TAF5, TAF6, TAF7, TAF8, TAF9, TAF10, TAF11, TAF12 and TAF13 (PubMed:33795473). TAF13, together with TAF11 and TBP, play key roles during promoter binding by the TFIID and TFIIA transcription factor complexes (PubMed:33795473)","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q15543/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/TAF13","classification":"Common Essential","n_dependent_lines":514,"n_total_lines":1208,"dependency_fraction":0.42549668874172186},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/TAF13","total_profiled":1310},"omim":[{"mim_id":"617432","title":"INTELLECTUAL DEVELOPMENTAL DISORDER, AUTOSOMAL RECESSIVE 60; MRT60","url":"https://www.omim.org/entry/617432"},{"mim_id":"606576","title":"TAF3 RNA POLYMERASE II, TATA BOX-BINDING PROTEIN-ASSOCIATED FACTOR, 140-KD; TAF3","url":"https://www.omim.org/entry/606576"},{"mim_id":"600774","title":"TAF13 RNA POLYMERASE II, TATA BOX-BINDING PROTEIN-ASSOCIATED FACTOR, 18-KD; TAF13","url":"https://www.omim.org/entry/600774"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Nucleoplasm","reliability":"Enhanced"},{"location":"Nucleoli","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/TAF13"},"hgnc":{"alias_symbol":["TAFII18"],"prev_symbol":["TAF2K"]},"alphafold":{"accession":"Q15543","domains":[{"cath_id":"1.10.20.10","chopping":"30-77","consensus_level":"medium","plddt":95.7154,"start":30,"end":77},{"cath_id":"1.20.5","chopping":"92-124","consensus_level":"medium","plddt":89.6291,"start":92,"end":124}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q15543","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q15543-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q15543-F1-predicted_aligned_error_v6.png","plddt_mean":82.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TAF13","jax_strain_url":"https://www.jax.org/strain/search?query=TAF13"},"sequence":{"accession":"Q15543","fasta_url":"https://rest.uniprot.org/uniprotkb/Q15543.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q15543/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q15543"}},"corpus_meta":[{"pmid":"9726987","id":"PMC_9726987","title":"A human SPT3-TAFII31-GCN5-L acetylase complex distinct from transcription factor IID.","date":"1998","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9726987","citation_count":166,"is_preprint":false},{"pmid":"8649367","id":"PMC_8649367","title":"Yeast RSP5 and its human homolog hRPF1 potentiate hormone-dependent activation of transcription by human progesterone and glucocorticoid receptors.","date":"1996","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/8649367","citation_count":140,"is_preprint":false},{"pmid":"28918900","id":"PMC_28918900","title":"Transcription of Nearly All Yeast RNA Polymerase II-Transcribed Genes Is Dependent on Transcription Factor TFIID.","date":"2017","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/28918900","citation_count":129,"is_preprint":false},{"pmid":"12840001","id":"PMC_12840001","title":"Systematic analysis of essential yeast TAFs in genome-wide transcription and 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TAF11/TAF13 competes with TATA-box DNA for binding to the DNA-binding surface of TBP, and also competes with the N-terminal domain of TAF1 (previously implicated in TATA-box mimicry). A highly conserved C-terminal TBP-interaction domain (CTID) in TAF13 is essential for supporting cell growth.\",\n      \"method\": \"Crystal structure determination, cross-linking mass spectrometry (CLMS), biochemical binding assays, mutagenesis\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — integrative structural study combining crystal coordinates, CLMS, and biochemical validation with mutagenesis in a single rigorous study\",\n      \"pmids\": [\"29111974\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Pathogenic missense variants in TAF13 (p.Met40Lys and p.Leu31His) impair formation of the TAF13-TAF11 histone-like heterodimer, which is required for recruitment of TAF11/TAF13 into TFIID. This disruption is associated with intellectual disability and microcephaly. TAF13 knockdown in neuroblastoma cells leads to deregulation of genes related to neuronal and skeletal functions and those containing E-box motifs.\",\n      \"method\": \"Co-immunoprecipitation in HeLa cells, molecular modeling, RNA sequencing upon TAF13 knockdown\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP with disease variants plus transcriptomic functional readout, replicated across two independent families\",\n      \"pmids\": [\"28257693\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"In yeast TFIID, TAF11 and TAF13 provide critical functional contacts with TBP during preinitiation complex (PIC) assembly, as revealed by temperature-sensitive mutant analysis; loss of TAF13 function reduces TBP recruitment to promoters.\",\n      \"method\": \"Temperature-sensitive yeast mutants, genome-wide expression profiling, chromatin immunoprecipitation for PIC assembly\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with temperature-sensitive alleles, ChIP-based PIC assembly assays, replicated across all 13 essential TAF mutants providing strong internal controls\",\n      \"pmids\": [\"12840001\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Specific amino acids in the alpha2-helix of hTAFII28 (TAF13's heterodimer partner) mediate interaction with TAFII18 (TAF13) at the hydrophobic interface; mutation of these residues abolishes the hTAFII28-TAFII18 interaction and disrupts synergistic transcriptional activation with TBP.\",\n      \"method\": \"Mutagenesis of histone fold domain residues, mammalian cell transcription assays with altered-specificity TBP mutant\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — mutagenesis-based in vivo transcription assay, single lab, establishes the hydrophobic interface between TAF13 and TAF11 but indirect (TAF13 inferred as the binding partner)\",\n      \"pmids\": [\"10373554\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Yeast TAF19 (FUN81), the homologue of human TAFII18/TAF13, co-immunoprecipitates with TBP and is present in complexes containing the TAFII130 subunit, establishing it as a bona fide component of the TFIID complex.\",\n      \"method\": \"Coimmunoprecipitation, sequence homology, essential gene viability assay in yeast\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP demonstrating TBP and TFIID association in yeast, confirmed across multiple TAF subunits in same study\",\n      \"pmids\": [\"8962109\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Human TAFII18 (TAF13) is not associated in vivo with human TBP/TFIID or with a TFIID-related TBP-free TAF complex, establishing that it is not a component of the human STAGA complex (which contains the related hSPT3).\",\n      \"method\": \"Native complex immunoprecipitation and Western blotting from human cell extracts\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — negative result from Co-IP fractionation, single lab; establishes TAFII18/TAF13 is excluded from STAGA but does not exclude TFIID membership\",\n      \"pmids\": [\"9726987\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Rapid degron-dependent depletion of yeast Taf13 strongly reduces nascent transcription of nearly all RNA Pol II-transcribed genes, demonstrating that TAF13 is broadly required for TFIID-dependent transcription across gene classes (TATA and TATA-less, Taf1-enriched and Taf1-depleted).\",\n      \"method\": \"Auxin-inducible degron depletion, nascent transcription measurement (NET-seq/GRO-seq type assay), genome-wide\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — acute protein depletion with nascent transcript measurement, replicated across multiple TAF subunits, genome-wide readout\",\n      \"pmids\": [\"28918900\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Taf13 knockout in mice causes embryonic lethality after implantation; Taf13-null embryos successfully implant and form egg-cylinder stages but fail to initiate gastrulation. TAF13 deficiency leads to depletion of pluripotency factors OCT4, NANOG, and SOX2, demonstrating an essential role in maintaining pluripotency.\",\n      \"method\": \"Conditional/constitutive mouse knockout, immunofluorescence for pluripotency markers, transcriptomic analysis\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean knockout with defined phenotypic readout (gastrulation failure, pluripotency factor depletion), protein-level validation of pluripotency markers\",\n      \"pmids\": [\"38593904\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In mouse embryonic stem cells, Taf13 loss had little effect on overall TFIID integrity and caused only a mild reduction of TBP promoter recruitment, but led to altered PIC formation and globally reduced RNA Pol II recruitment. Thus, the TAF11-TAF13 heterodimer is not essential for TBP/TFIID promoter recruitment, revealing plasticity in PIC assembly pathways.\",\n      \"method\": \"Gene inactivation in mouse ESCs, ChIP-seq for TBP and Pol II, cryo-EM-informed genetic analysis\",\n      \"journal\": \"iScience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean genetic loss-of-function with ChIP-seq readout for TBP and Pol II occupancy genome-wide, directly testing cryo-EM model prediction\",\n      \"pmids\": [\"40491483\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"In yeast, depletion of Taf13 suppresses the overactivation of TFIID-dependent genes caused by separation of Mediator core and tail modules, placing TAF13/TFIID downstream of Mediator core-tail integrity in the transcriptional regulatory hierarchy.\",\n      \"method\": \"Genetic epistasis in yeast (double mutant: Taf13 depletion × Med16 deletion), mRNA expression profiling\",\n      \"journal\": \"G3 (Bethesda, Md.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — genetic epistasis with expression readout, single lab, effect on TFIID genomic occupancy not fully resolved\",\n      \"pmids\": [\"36331351\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TAF13 (TAFII18) is a core subunit of the general transcription factor TFIID that forms a histone fold heterodimer with TAF11; the TAF11/TAF13 complex binds to the DNA-binding surface of TBP, competing with both TATA-box DNA and the TAF1 N-terminal domain, thereby regulating TFIID assembly and PIC formation—though TAF11/TAF13 is not strictly required for TBP promoter recruitment, its loss reduces RNA Pol II recruitment and is essential for gastrulation and maintenance of pluripotency in mammals, with disease-causing variants in its TAF11-interaction interface causing intellectual disability and microcephaly.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TAF13 (TAFII18) is a core histone-fold subunit of the general transcription factor TFIID that governs RNA polymerase II preinitiation complex (PIC) assembly across the genome [#0, #6]. It pairs with TAF11 through reciprocal histone-fold domains to form a heterodimer, and this heterodimer engages the DNA-binding surface of TBP, competing with both TATA-box DNA and the TATA-mimicking N-terminal domain of TAF1; a conserved C-terminal TBP-interaction domain in TAF13 is required for cell growth [#0]. TAF13 is a bona fide TFIID component that provides functional contacts with TBP during PIC assembly, and its acute loss broadly reduces nascent transcription of nearly all Pol II genes regardless of TATA-box status or TAF1 enrichment [#2, #6]. Genetically, TAF13/TFIID acts downstream of Mediator core-tail integrity in the transcriptional regulatory hierarchy [#9]. In mammals TAF13 is essential for development: its knockout blocks gastrulation and depletes the pluripotency factors OCT4, NANOG, and SOX2 in mouse embryos [#7]. Notably, loss of the TAF11-TAF13 heterodimer in mouse ESCs leaves overall TFIID integrity and TBP promoter recruitment largely intact yet still impairs PIC formation and globally reduces Pol II recruitment, revealing plasticity in PIC assembly pathways [#8]. Pathogenic missense variants in the TAF13 interface that forms the TAF11 heterodimer cause intellectual disability and microcephaly [#1].\",\n  \"teleology\": [\n    {\n      \"year\": 1996,\n      \"claim\": \"Established that the human TAFII18/TAF13 homologue is a genuine constituent of TFIID rather than an isolated factor, answering whether this small subunit belongs to the TBP-containing complex.\",\n      \"evidence\": \"Co-immunoprecipitation with TBP and the TAFII130 subunit in yeast plus essential-gene viability assay\",\n      \"pmids\": [\"8962109\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not define how TAF13 contacts TBP\", \"Membership demonstrated in yeast, not yet structurally resolved\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Delimited the complex membership of TAFII18/TAF13 by showing it is excluded from the TBP-free STAGA complex, distinguishing it from related histone-fold subunits.\",\n      \"evidence\": \"Native complex immunoprecipitation and Western blotting from human cell extracts\",\n      \"pmids\": [\"9726987\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Negative result from a single lab\", \"Does not resolve TAF13's quantitative contribution to TFIID\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Mapped the physical interface mediating the histone-fold heterodimer, showing specific alpha2-helix residues drive partner binding and synergistic activation with TBP.\",\n      \"evidence\": \"Mutagenesis of histone-fold residues and mammalian transcription assays with an altered-specificity TBP mutant\",\n      \"pmids\": [\"10373554\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"TAF13 inferred as binding partner rather than directly assayed\", \"Single-lab in vivo transcription readout\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Demonstrated that TAF11 and TAF13 provide functionally critical contacts with TBP during PIC assembly, linking the subunit to promoter recruitment in vivo.\",\n      \"evidence\": \"Temperature-sensitive yeast TAF mutants with genome-wide expression profiling and ChIP for PIC assembly\",\n      \"pmids\": [\"12840001\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Temperature-sensitive alleles may produce indirect effects\", \"Structural basis of TBP contact not defined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Resolved the structural logic of TAF13 function, showing the TAF11/TAF13 heterodimer binds the TBP DNA-binding surface in competition with TATA DNA and the TAF1 N-terminal domain, and defined a conserved CTID essential for growth.\",\n      \"evidence\": \"Crystal structure, cross-linking mass spectrometry, biochemical binding assays and mutagenesis\",\n      \"pmids\": [\"29111974\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of TBP-surface competition for in vivo PIC dynamics not fully defined\", \"Does not resolve order of events during PIC assembly\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Connected TAF13 to human disease by showing missense variants that disrupt the TAF11-TAF13 heterodimer and TFIID incorporation cause intellectual disability and microcephaly.\",\n      \"evidence\": \"Co-immunoprecipitation with disease variants in HeLa cells, molecular modeling, and RNA-seq after TAF13 knockdown across two families\",\n      \"pmids\": [\"28257693\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Causal chain from transcriptional deregulation to neurodevelopmental phenotype not established\", \"E-box gene deregulation mechanism unresolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Established that TAF13 is broadly required for TFIID-dependent transcription, showing acute depletion reduces nascent transcription of nearly all Pol II genes regardless of promoter class.\",\n      \"evidence\": \"Auxin-inducible degron depletion of yeast Taf13 with genome-wide nascent transcript measurement\",\n      \"pmids\": [\"28918900\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not distinguish direct versus indirect effects on individual genes\", \"Mechanism downstream of TBP contact not resolved\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Positioned TAF13/TFIID downstream of Mediator core-tail integrity, ordering it within the transcriptional regulatory hierarchy.\",\n      \"evidence\": \"Genetic epistasis in yeast (Taf13 depletion x Med16 deletion) with mRNA expression profiling\",\n      \"pmids\": [\"36331351\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Effect on TFIID genomic occupancy not fully resolved\", \"Single-lab epistasis\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defined an essential mammalian developmental role, showing Taf13 is required for gastrulation and maintenance of the OCT4/NANOG/SOX2 pluripotency network.\",\n      \"evidence\": \"Mouse knockout with immunofluorescence for pluripotency markers and transcriptomic analysis\",\n      \"pmids\": [\"38593904\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether pluripotency factor loss is a direct transcriptional effect not established\", \"Stage-specific requirement before implantation untested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Revealed plasticity in PIC assembly, showing the TAF11-TAF13 heterodimer is dispensable for TBP/TFIID promoter recruitment yet still required for normal PIC formation and Pol II recruitment.\",\n      \"evidence\": \"Gene inactivation in mouse ESCs with ChIP-seq for TBP and Pol II, interpreted against cryo-EM models\",\n      \"pmids\": [\"40491483\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Alternative PIC assembly pathway not molecularly defined\", \"Reconciliation with broad transcriptional requirement seen in yeast incomplete\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How TAF13's structural competition with TATA DNA and TAF1 is dynamically resolved during PIC assembly, and how this links to its developmental and disease functions, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No time-resolved model of PIC assembly steps requiring TAF11/TAF13\", \"Mechanism linking transcriptional defects to pluripotency loss and neurodevelopmental disease unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 2, 6]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [2, 6]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"complexes\": [\"TFIID\"],\n    \"partners\": [\"TAF11\", \"TBP\", \"TAF1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}