{"gene":"TAF5","run_date":"2026-06-10T10:51:54","timeline":{"discoveries":[{"year":1997,"finding":"Human TAF5 (hTAFII100) is an integral subunit of TFIID that interacts strongly with histone H4-related hTAFII80 and histone H3-related hTAFII31 (both separately and as a stable complex), and shows weaker interactions with TBP, hTAFII250, hTAFII28, and hTAFII20, but not hTAFII55. Anti-hTAFII100 antibodies selectively inhibit basal transcription from a TATA-less initiator-containing promoter but not a TATA-containing promoter, suggesting a core promoter-specific function.","method":"Immunoprecipitation (in vivo and in vitro binding assays), antibody inhibition of in vitro transcription","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP plus functional in vitro transcription inhibition assay with multiple orthogonal methods in one study","pmids":["9045704"],"is_preprint":false},{"year":2004,"finding":"Yeast TFIID contains two copies of WD-40 repeat-containing TAF5, with its C- and N-termini located in different lobes of the trilobed TFIID structure. A recombinant complex containing TAF5 complexed with six histone fold-containing TAFs can form a trilobed structure. TAF5 contributes to the linker domains connecting the lobes.","method":"Electron microscopy, digital image analysis, immunomapping, reconstitution of recombinant subcomplex","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — EM structure combined with immunomapping and reconstitution of recombinant complex, multiple orthogonal methods","pmids":["14765106"],"is_preprint":false},{"year":2006,"finding":"In Drosophila, RNAi knockdown of TAF5 (along with TAF4, TAF6, TAF9, TAF12) destabilizes the TFIID complex in vivo, indicating TAF5 plays a key role in TFIID stability. TAF5 contributes to a stable core subcomplex (with TAF4, TAF6, TAF9, TAF12). In contrast to TAF1 and TAF4, RNAi knockdown of TAF5 had little effect on transcription from either TATA-containing or TATA-less DPE-containing promoters.","method":"RNAi knockdown in Drosophila tissue culture cells, in vitro transcription assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean RNAi knockdown with defined complex stability and transcription phenotype readouts, multiple subunits tested in parallel","pmids":["16895980"],"is_preprint":false},{"year":2007,"finding":"Crystal structure of the human TAF5-NTD2 domain at 2.2 Å resolution reveals an alpha-helical domain with distant structural similarity to RNA polymerase II CTD-interacting factors, containing several conserved clefts likely critical for TFIID assembly. Biochemical analysis shows the N-terminal half of TAF5 forms a flexible, extended dimer, a key property for TFIID complex assembly.","method":"X-ray crystallography (2.2 Å), biochemical dimerization assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure plus biochemical dimerization assay in a single study, rigorous structural validation","pmids":["17227857"],"is_preprint":false},{"year":2007,"finding":"TFIID subunits TAF4, TAF5, and TBP are detected on the p21 core promoter prior to TAF1 upon UV-induced DNA damage in cells, suggesting that distinct TFIID subunits can be recruited separately to the promoter, with TAF5 being part of the initial promoter-bound TFIID scaffold.","method":"Chromatin immunoprecipitation (ChIP) at the p21 promoter in UV-irradiated cells","journal":"Molecular cell","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — ChIP in a single lab, single method showing sequential recruitment","pmids":["17996705"],"is_preprint":false},{"year":2009,"finding":"The SAYP transcription coactivator directly binds the TAF5 subunit of TFIID through its evolutionarily conserved SAY activation domain, thereby coupling the chromatin-remodeling factor Brahma (SWI/SNF) and TFIID into a stable supercomplex called BTFly. This interaction is required for transcription activation.","method":"Protein interaction assays (direct binding of SAY domain to TAF5), co-immunoprecipitation, functional transcription assays in Drosophila","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding assay plus Co-IP plus functional transcription assay, single lab","pmids":["19541607"],"is_preprint":false},{"year":2010,"finding":"Yeast Taf5 contains a Rap1-binding domain (RBD) that is essential for viability and required for transcription of ribosomal protein genes. The Taf5 RBD is dispensable for Taf-Taf interactions and TFIID stability. Cells with altered Taf5 RBD show reduced Rap1-binding affinity and selective defects in ribosomal protein gene transcription.","method":"Mutagenesis of Rap1-binding domain, in vitro binding assays, yeast genetics, gene-specific transcription assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — domain mutagenesis combined with binding assays, viability assays, and gene-specific transcription readout, multiple orthogonal methods","pmids":["20189987"],"is_preprint":false},{"year":2012,"finding":"TAF5 modulates the formation of the TAF6-TAF9 complex: mutations in the HEAT repeat domain of TAF6 that disrupt TAF6-TAF9 interaction have an even stronger effect in the context of a TAF5-TAF6-TAF9 trimeric complex, indicating TAF5 plays a regulatory role in TAF6-TAF9 submodule assembly within TFIID.","method":"Crystal structure of TAF6C domain (1.9 Å), mutagenesis, co-immunoprecipitation in HeLa cells, in vitro protein interaction assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure plus mutagenesis plus Co-IP in cells, multiple orthogonal approaches in one study","pmids":["22696218"],"is_preprint":false},{"year":2012,"finding":"TAF5 is associated with RNA polymerase II-transcribed snRNA genes by ChIP, but the full complement of TAFs at these genes differs from protein-coding gene promoters; TAF5 is present on snRNA genes whereas TAF1, TAF10, and TAF4 are not detected, indicating TAF5 is part of a distinct, snRNA gene-specific TBP/TAF complex.","method":"ChIP and siRNA-mediated knockdown","journal":"Transcription","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — ChIP combined with siRNA, single lab, single method per TAF","pmids":["22441827"],"is_preprint":false},{"year":2013,"finding":"Cryo-EM structure of human core-TFIID at 11.6 Å resolution reveals a two-fold symmetric, interlaced architecture accommodating TAF4, TAF5, TAF6, TAF9, and TAF12 with their histone folds. TAF5 contributes to this symmetric core. Binding of one TAF8-TAF10 complex breaks the original symmetry, producing an asymmetric scaffold for holo-TFIID assembly.","method":"Cryo-electron microscopy (11.6 Å), biochemical reconstitution of core-TFIID subcomplex","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — cryo-EM structure combined with biochemical reconstitution, published in high-impact journal with rigorous validation","pmids":["23292512"],"is_preprint":false},{"year":2017,"finding":"Yeast Taf5 is a direct binding target of the Rap1 transcriptional activation domain (AD). Mutation of the newly identified Rap1 AD reduces the efficiency of Rap1 binding to Taf5, confirming Taf5 as a functional coactivator target for Rap1-dependent gene transcription.","method":"Altered DNA-binding specificity variant (Rap1AS), in vitro binding assays to Taf5, transcription reporter assays","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding assay plus functional transcription assay using engineered specificity variant, single lab","pmids":["28196871"],"is_preprint":false},{"year":2018,"finding":"The chaperonin CCT specifically associates with nascent TAF5 in the cytoplasm as a checkpoint for TFIID assembly, facilitating handover of TAF5 to TAF6-TAF9 for subsequent holo-TFIID formation. Structural and mutational analysis of the cytoplasmic TAF5-TAF6-TAF9 submodule identified novel interactions crucial for TFIID integrity and for allocation of TAF9 to either TFIID or the SAGA co-activator complex.","method":"Quantitative proteomics, structural analysis, mutagenesis of TAF5-TAF6-TAF9 submodule, co-immunoprecipitation in human cells","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — quantitative proteomics, structural analysis, and mutagenesis combined with cellular assembly assays in one rigorous study","pmids":["30510221"],"is_preprint":false},{"year":2018,"finding":"Cryo-EM structure of promoter-bound yeast TFIID at better than 5 Å resolution reveals that TAF5 and TAF6 form a topologically closed tetramer that stabilizes the compact trilobed architecture of TFIID. This structural analysis confirms unique subunit stoichiometry in TFIID and reveals a hexameric arrangement of histone fold domain-containing TAFs in the Twin lobe.","method":"Cryo-electron microscopy (sub-5 Å), cross-linking mass spectrometry, crystal structure docking","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — cryo-EM structure combined with cross-linking studies and crystal structure placement, multiple orthogonal methods","pmids":["30405110"],"is_preprint":false},{"year":2018,"finding":"Overexpression of TAF5 (but not TAF9, TAF12, or TBP) suppresses the temperature-sensitive phenotype caused by TAF6 histone-fold domain (HFD) mutations in yeast, revealing a specific genetic and functional relationship between TAF5 and the TAF6 HFD in TFIID assembly and transcriptional activation.","method":"Yeast genetic suppression analysis, coimmunoprecipitation from yeast cell extracts","journal":"The FEBS journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic suppression combined with Co-IP, single lab, two orthogonal methods","pmids":["29485702"],"is_preprint":false},{"year":2020,"finding":"Cryo-EM structure of yeast SAGA reveals that the core module contains Taf5 (ortholog of human TAF5) along with Sgf73, Spt20, and a histone octamer-like fold. Taf5 and the Taf6 HEAT domain adopt distinct conformations in SAGA compared to TFIID, explaining the functional specialization between these two complexes sharing the same subunit.","method":"Cryo-electron microscopy (3.3 Å resolution for core module)","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — cryo-EM structure at 3.3 Å for the core module, published in Nature with rigorous structural validation","pmids":["31969703"],"is_preprint":false},{"year":2002,"finding":"C. elegans TAF-5 (ortholog of human TAF5/TAFII100) is required for a significant fraction of embryonic mRNA transcription as shown by RNAi, but is not essential for expression of multiple developmental and metazoan-specific genes. This phenotype resembles that of TAF-9 and TAF-10 depletion, suggesting TAF-5 is part of a functional module that can be bypassed at many metazoan-specific promoters.","method":"RNA interference in C. elegans embryos, RT-PCR analysis of multiple gene targets","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean RNAi in whole organism with multiple gene expression readouts, consistent with companion studies","pmids":["12458202"],"is_preprint":false},{"year":2001,"finding":"C. elegans taf-5 (human TAFII130 ortholog) is required for essentially all early embryonic mRNA transcription as shown by RNAi, in contrast to taf-10 and taf-11 which have modular functions and can be bypassed at many developmental genes. This suggests a broad structural requirement for TAF-5 in either TFIID or TFTC-like complexes.","method":"RNAi in C. elegans embryos, transcriptional analysis of multiple developmental genes","journal":"The EMBO journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RNAi with parallel comparison of multiple TAF subunits and multiple gene expression readouts","pmids":["11566890"],"is_preprint":false},{"year":2024,"finding":"Inclusion of the TAF5 alternative exon-8 is required for assembly of the TFIID general transcription initiation complex in human cells; deletion or splice-site mutation of this exon disrupts TFIID assembly and reduces global gene expression output.","method":"Massively parallel exon deletion and splice-site mutation CRISPR screens, followed by mechanistic validation of TAF5 exon-8 effect on TFIID assembly and global gene expression","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — genome-scale CRISPR screen with in-depth mechanistic follow-up showing TFIID assembly defect and global transcription impact","pmids":["38917794"],"is_preprint":false},{"year":2023,"finding":"Loss of taf5 in zebrafish (nonsense mutation identified by forward genetic screen, confirmed by CRISPR/Cas9) causes craniofacial hypoplasia, ventricular hypoplasia, heart failure, and lethality. taf5-/- zebrafish display misregulation of metabolic gene expression, altered respiration, and metabolite changes, suggesting TAF5 contributes to cardiac and craniofacial development through regulation of metabolism.","method":"Forward genetic screen, CRISPR/Cas9 gene editing, RNA sequencing, respiration assays, metabolite studies in zebrafish","journal":"Biology open","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockout with multiple orthogonal mechanistic readouts (RNA-seq, respiration, metabolomics), single lab","pmids":["37746814"],"is_preprint":false},{"year":2024,"finding":"Mouse embryos with disrupted Taf5 fail to implant post-blastocyst formation and show aberrant lineage specification within the inner cell mass. Transcriptomic analysis reveals distinct gene targets affected by Taf5 loss compared to Taf12 or Taf13 loss, indicating TAF5 conveys locus specificity to TFIID in early mammalian development.","method":"Conditional knockout in mouse, transcriptomic analysis (RNA-seq), immunofluorescence for lineage markers","journal":"Developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean knockout with transcriptomic analysis and immunostaining, single lab, multiple TAF subunits compared in parallel","pmids":["38593904"],"is_preprint":false},{"year":2025,"finding":"In human SAGA, TAF5L (the SAGA-specific paralog of TAF5 that arose by gene duplication in metazoans) adopts structural differences compared to canonical TAF5 that are directly implicated in accommodating the splicing-factor module (SPL). TAF6L's HEAT repeat domain provides a docking surface for SPL, with multiple differences between TAF6L/TAF5L and the canonical TFIID paralogs (TAF5/TAF6) required for this structural re-arrangement.","method":"Cryo-EM structure of endogenous human SAGA purified by affinity-ligand (high-resolution structure of SPL and TAF6L HEAT domain)","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — cryo-EM structure with rigorous method, but preprint not yet peer-reviewed and specifically concerns the TAF5L paralog in SAGA rather than TAF5 in TFIID","pmids":["bio_10.1101_2025.07.31.667873"],"is_preprint":true}],"current_model":"TAF5 is an essential ~100 kDa WD-40 repeat-containing subunit of TFIID that forms a flexible N-terminal dimer and serves as a structural scaffold for TFIID assembly: it nucleates a symmetric core subcomplex with TAF4, TAF6, TAF9, and TAF12, is chaperoned by CCT during cytoplasmic assembly before handover to TAF6-TAF9, contains a Rap1-binding domain required for ribosomal protein gene transcription, contributes to a linker domain spanning TFIID lobes, and its alternative exon-8 inclusion is required for functional TFIID assembly and global gene expression; TAF5 also participates in SAGA (via its yeast ortholog Taf5) and can serve as a direct binding target for transcriptional activators and coactivators such as SAYP."},"narrative":{"mechanistic_narrative":"TAF5 is an essential WD-40 repeat-containing subunit of the general transcription factor TFIID that functions principally as a structural scaffold for complex assembly and integrity [PMID:9045704, PMID:16895980]. It nucleates a two-fold symmetric core subcomplex with the histone-fold TAFs TAF4, TAF6, TAF9, and TAF12, and RNAi depletion of TAF5 destabilizes TFIID in vivo, defining it as a stability determinant of the complex [PMID:16895980, PMID:23292512]. The N-terminal half of TAF5 forms a flexible, extended dimer, and its two copies span the trilobed TFIID architecture, with TAF5 and TAF6 forming a topologically closed tetramer that stabilizes the compact lobed structure and contributes the linker domains connecting lobes [PMID:14765106, PMID:17227857, PMID:30405110]. TAF5 regulates assembly of the TAF6-TAF9 submodule, and its incorporation is gated by the chaperonin CCT, which captures nascent cytoplasmic TAF5 before handing it over to TAF6-TAF9 for holo-TFIID formation [PMID:22696218, PMID:30510221]. Beyond its scaffolding role, TAF5 serves as a direct target of transcriptional activators and coactivators: the SAYP coactivator binds TAF5 to couple SWI/SNF chromatin remodeling and TFIID into a supercomplex, and the yeast ortholog contains a Rap1-binding domain required for ribosomal protein gene transcription [PMID:19541607, PMID:20189987, PMID:28196871]. The shared subunit also resides in the SAGA coactivator core, where it adopts a distinct conformation from TFIID [PMID:31969703]. Functionally, TAF5 is required for the bulk of embryonic mRNA transcription and conveys locus specificity to TFIID during early development, with its loss causing failed implantation in mouse and craniofacial and cardiac defects in zebrafish; inclusion of its alternative exon-8 is required for TFIID assembly and global gene expression in human cells [PMID:11566890, PMID:38917794, PMID:37746814, PMID:38593904].","teleology":[{"year":1997,"claim":"Established TAF5 as an integral TFIID subunit with selective interactions among the histone-fold TAFs and a core-promoter-specific function, distinguishing TATA-less from TATA-containing promoter requirements.","evidence":"Co-IP and antibody inhibition of in vitro transcription on defined promoters","pmids":["9045704"],"confidence":"High","gaps":["Did not resolve TAF5 architecture within TFIID","Mechanism of promoter selectivity not defined structurally"]},{"year":2004,"claim":"Mapped TAF5 within the trilobed TFIID, showing two copies span separate lobes and contribute the inter-lobe linker, establishing its scaffolding geometry.","evidence":"EM, immunomapping, and reconstitution of a recombinant TAF5/histone-fold TAF subcomplex in yeast","pmids":["14765106"],"confidence":"High","gaps":["Low resolution precluded atomic interactions","Did not define assembly order"]},{"year":2007,"claim":"Resolved the TAF5 N-terminal domain structure and demonstrated it forms a flexible extended dimer, identifying a biochemical property required for TFIID assembly.","evidence":"X-ray crystallography of NTD2 (2.2 Å) plus biochemical dimerization assays","pmids":["17227857"],"confidence":"High","gaps":["Functional consequence of dimerization in cells not tested","Partner contacts of NTD2 clefts unidentified"]},{"year":2006,"claim":"Showed TAF5 is a stability determinant of TFIID, contributing to a stable core subcomplex, while having limited direct effect on transcription of tested promoters.","evidence":"RNAi knockdown in Drosophila cells with complex-stability and in vitro transcription readouts","pmids":["16895980"],"confidence":"High","gaps":["Genome-wide transcriptional impact not assessed","Distinction between scaffolding and direct transcriptional roles unresolved"]},{"year":2010,"claim":"Identified a Rap1-binding domain in yeast Taf5 required for ribosomal protein gene transcription but dispensable for TFIID integrity, separating an activator-recruitment function from the scaffolding role.","evidence":"Domain mutagenesis, in vitro binding, yeast genetics, and gene-specific transcription assays","pmids":["20189987"],"confidence":"High","gaps":["Whether human TAF5 carries an equivalent activator-binding surface unknown","Structural basis of Rap1 contact undefined"]},{"year":2009,"claim":"Demonstrated TAF5 is a direct docking target for the SAYP coactivator, coupling SWI/SNF chromatin remodeling to TFIID in an activation-required supercomplex.","evidence":"Direct binding, Co-IP, and functional transcription assays in Drosophila","pmids":["19541607"],"confidence":"Medium","gaps":["Binding interface on TAF5 not mapped","Conservation in mammals not shown"]},{"year":2012,"claim":"Defined TAF5 as a regulator of TAF6-TAF9 submodule assembly and refined the human core-TFIID architecture, showing TAF5 within a two-fold symmetric core whose symmetry is broken by TAF8-TAF10 binding.","evidence":"TAF6C crystal structure, mutagenesis, Co-IP (idx 7) and cryo-EM of core-TFIID with reconstitution (idx 9)","pmids":["22696218","23292512"],"confidence":"High","gaps":["Order of TAF5 entry into the assembly pathway not yet established","ChIP-based snRNA-gene and p21 recruitment claims (idx 4, 8) were single-method"]},{"year":2018,"claim":"Placed TAF5 at the center of a chaperoned, ordered cytoplasmic assembly pathway, with CCT capturing nascent TAF5 as a checkpoint before handover to TAF6-TAF9, and resolved a TAF5-TAF6 tetramer stabilizing the trilobed TFIID.","evidence":"Quantitative proteomics, structural and mutational analysis of the TAF5-TAF6-TAF9 submodule (idx 11), cryo-EM of promoter-bound yeast TFIID with cross-linking MS (idx 12), and yeast genetic suppression (idx 13)","pmids":["30510221","30405110","29485702"],"confidence":"High","gaps":["Trigger that releases TAF5 from CCT not defined","How TAF9 is partitioned between TFIID and SAGA mechanistically unresolved"]},{"year":2020,"claim":"Showed the same Taf5 subunit adopts distinct conformations in SAGA versus TFIID, providing a structural basis for functional specialization of a shared subunit between two coactivator complexes.","evidence":"Cryo-EM of yeast SAGA core module (3.3 Å)","pmids":["31969703"],"confidence":"High","gaps":["Determinants directing TAF5 to SAGA versus TFIID not identified","Human SAGA-specific paralog relationships addressed only later (idx 20, preprint)"]},{"year":2024,"claim":"Connected TAF5 to organismal phenotypes and locus-specific transcription, showing it is required for early embryonic transcription, conveys locus specificity in mammalian development, and that its alternative exon-8 is required for TFIID assembly and global expression.","evidence":"C. elegans/mouse RNAi and conditional knockout with RNA-seq (idx 16, 19), zebrafish forward-genetic knockout with metabolomics (idx 18), and CRISPR exon-deletion screens with mechanistic validation in human cells (idx 17)","pmids":["11566890","38593904","37746814","38917794"],"confidence":"Medium","gaps":["Molecular basis of locus specificity conferred by TAF5 not defined","Whether developmental phenotypes reflect TFIID assembly defects versus selective gene targets unresolved"]},{"year":null,"claim":"How TAF5 mechanistically directs promoter and locus selectivity within TFIID, and what governs its release from CCT and partitioning between TFIID and SAGA, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model linking TAF5 conformation to gene-specific output","CCT-release trigger unknown","Human activator-binding surface analogous to yeast Rap1-binding domain not defined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[1,2,3,9,12]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[5,11]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,6,17]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,4]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[11]}],"pathway":[{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,2,17]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[18,19]}],"complexes":["TFIID","SAGA","core-TFIID (TAF5-TAF6-TAF9-TAF4-TAF12)","BTFly supercomplex"],"partners":["TAF6","TAF9","TAF4","TAF12","CCT","SAYP","RAP1","TBP"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q15542","full_name":"Transcription initiation factor TFIID subunit 5","aliases":["Transcription initiation factor TFIID 100 kDa subunit","TAF(II)100","TAFII-100","TAFII100"],"length_aa":800,"mass_kda":86.8,"function":"The TFIID basal transcription factor complex plays a major role in the initiation of RNA polymerase II (Pol II)-dependent transcription (PubMed:33795473). TFIID recognizes and binds promoters with or without a TATA box 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, PubMed:8758937, PubMed:8942982, PubMed:9045704). The TFIID complex structure can be divided into 3 modules TFIID-A, TFIID-B, and TFIID-C (PubMed:33795473). TAF5 is involved in two modules of TFIID, in TFIID-A together with TAF3 and TBP, and in TFIID-B with TAF8 (PubMed:33795473). Involved in contacts between TFIID and TFIIF in the PIC (PubMed:33795473)","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q15542/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/TAF5","classification":"Common Essential","n_dependent_lines":1128,"n_total_lines":1208,"dependency_fraction":0.9337748344370861},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"TBP","stoichiometry":10.0},{"gene":"TAF12","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/TAF5","total_profiled":1310},"omim":[{"mim_id":"609514","title":"TATA BOX-BINDING PROTEIN-ASSOCIATED FACTOR 8; TAF8","url":"https://www.omim.org/entry/609514"},{"mim_id":"602955","title":"TAF6 RNA POLYMERASE II, TATA BOX-BINDING PROTEIN-ASSOCIATED FACTOR, 80-KD; TAF6","url":"https://www.omim.org/entry/602955"},{"mim_id":"601796","title":"TAF4 RNA POLYMERASE II, TATA BOX-BINDING PROTEIN-ASSOCIATED FACTOR, 135-KD; TAF4","url":"https://www.omim.org/entry/601796"},{"mim_id":"601787","title":"TAF5 RNA POLYMERASE II, TATA BOX-BINDING PROTEIN-ASSOCIATED FACTOR, 100-KD; TAF5","url":"https://www.omim.org/entry/601787"},{"mim_id":"600822","title":"TATA BOX-BINDING PROTEIN-ASSOCIATED FACTOR 9; TAF9","url":"https://www.omim.org/entry/600822"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"testis","ntpm":8.9}],"url":"https://www.proteinatlas.org/search/TAF5"},"hgnc":{"alias_symbol":["TAFII100"],"prev_symbol":["TAF2D"]},"alphafold":{"accession":"Q15542","domains":[{"cath_id":"1.25.40.500","chopping":"211-363","consensus_level":"high","plddt":91.3454,"start":211,"end":363},{"cath_id":"2.130.10.10","chopping":"462-747_762-796","consensus_level":"medium","plddt":93.2814,"start":462,"end":796}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q15542","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q15542-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q15542-F1-predicted_aligned_error_v6.png","plddt_mean":75.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TAF5","jax_strain_url":"https://www.jax.org/strain/search?query=TAF5"},"sequence":{"accession":"Q15542","fasta_url":"https://rest.uniprot.org/uniprotkb/Q15542.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q15542/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q15542"}},"corpus_meta":[{"pmid":"30563911","id":"PMC_30563911","title":"Human papillomavirus and the landscape of secondary genetic alterations in oral cancers.","date":"2018","source":"Genome research","url":"https://pubmed.ncbi.nlm.nih.gov/30563911","citation_count":180,"is_preprint":false},{"pmid":"32547891","id":"PMC_32547891","title":"Computational analysis of microRNA-mediated interactions in SARS-CoV-2 infection.","date":"2020","source":"PeerJ","url":"https://pubmed.ncbi.nlm.nih.gov/32547891","citation_count":156,"is_preprint":false},{"pmid":"16895980","id":"PMC_16895980","title":"TAF4 nucleates a core subcomplex of TFIID and mediates activated transcription from a TATA-less promoter.","date":"2006","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/16895980","citation_count":129,"is_preprint":false},{"pmid":"23292512","id":"PMC_23292512","title":"The architecture of human general transcription factor TFIID core 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Anti-hTAFII100 antibodies selectively inhibit basal transcription from a TATA-less initiator-containing promoter but not a TATA-containing promoter, suggesting a core promoter-specific function.\",\n      \"method\": \"Immunoprecipitation (in vivo and in vitro binding assays), antibody inhibition of in vitro transcription\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP plus functional in vitro transcription inhibition assay with multiple orthogonal methods in one study\",\n      \"pmids\": [\"9045704\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Yeast TFIID contains two copies of WD-40 repeat-containing TAF5, with its C- and N-termini located in different lobes of the trilobed TFIID structure. A recombinant complex containing TAF5 complexed with six histone fold-containing TAFs can form a trilobed structure. TAF5 contributes to the linker domains connecting the lobes.\",\n      \"method\": \"Electron microscopy, digital image analysis, immunomapping, reconstitution of recombinant subcomplex\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — EM structure combined with immunomapping and reconstitution of recombinant complex, multiple orthogonal methods\",\n      \"pmids\": [\"14765106\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"In Drosophila, RNAi knockdown of TAF5 (along with TAF4, TAF6, TAF9, TAF12) destabilizes the TFIID complex in vivo, indicating TAF5 plays a key role in TFIID stability. TAF5 contributes to a stable core subcomplex (with TAF4, TAF6, TAF9, TAF12). In contrast to TAF1 and TAF4, RNAi knockdown of TAF5 had little effect on transcription from either TATA-containing or TATA-less DPE-containing promoters.\",\n      \"method\": \"RNAi knockdown in Drosophila tissue culture cells, in vitro transcription assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean RNAi knockdown with defined complex stability and transcription phenotype readouts, multiple subunits tested in parallel\",\n      \"pmids\": [\"16895980\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Crystal structure of the human TAF5-NTD2 domain at 2.2 Å resolution reveals an alpha-helical domain with distant structural similarity to RNA polymerase II CTD-interacting factors, containing several conserved clefts likely critical for TFIID assembly. Biochemical analysis shows the N-terminal half of TAF5 forms a flexible, extended dimer, a key property for TFIID complex assembly.\",\n      \"method\": \"X-ray crystallography (2.2 Å), biochemical dimerization assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure plus biochemical dimerization assay in a single study, rigorous structural validation\",\n      \"pmids\": [\"17227857\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"TFIID subunits TAF4, TAF5, and TBP are detected on the p21 core promoter prior to TAF1 upon UV-induced DNA damage in cells, suggesting that distinct TFIID subunits can be recruited separately to the promoter, with TAF5 being part of the initial promoter-bound TFIID scaffold.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP) at the p21 promoter in UV-irradiated cells\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — ChIP in a single lab, single method showing sequential recruitment\",\n      \"pmids\": [\"17996705\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"The SAYP transcription coactivator directly binds the TAF5 subunit of TFIID through its evolutionarily conserved SAY activation domain, thereby coupling the chromatin-remodeling factor Brahma (SWI/SNF) and TFIID into a stable supercomplex called BTFly. This interaction is required for transcription activation.\",\n      \"method\": \"Protein interaction assays (direct binding of SAY domain to TAF5), co-immunoprecipitation, functional transcription assays in Drosophila\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding assay plus Co-IP plus functional transcription assay, single lab\",\n      \"pmids\": [\"19541607\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Yeast Taf5 contains a Rap1-binding domain (RBD) that is essential for viability and required for transcription of ribosomal protein genes. The Taf5 RBD is dispensable for Taf-Taf interactions and TFIID stability. Cells with altered Taf5 RBD show reduced Rap1-binding affinity and selective defects in ribosomal protein gene transcription.\",\n      \"method\": \"Mutagenesis of Rap1-binding domain, in vitro binding assays, yeast genetics, gene-specific transcription assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — domain mutagenesis combined with binding assays, viability assays, and gene-specific transcription readout, multiple orthogonal methods\",\n      \"pmids\": [\"20189987\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"TAF5 modulates the formation of the TAF6-TAF9 complex: mutations in the HEAT repeat domain of TAF6 that disrupt TAF6-TAF9 interaction have an even stronger effect in the context of a TAF5-TAF6-TAF9 trimeric complex, indicating TAF5 plays a regulatory role in TAF6-TAF9 submodule assembly within TFIID.\",\n      \"method\": \"Crystal structure of TAF6C domain (1.9 Å), mutagenesis, co-immunoprecipitation in HeLa cells, in vitro protein interaction assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure plus mutagenesis plus Co-IP in cells, multiple orthogonal approaches in one study\",\n      \"pmids\": [\"22696218\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"TAF5 is associated with RNA polymerase II-transcribed snRNA genes by ChIP, but the full complement of TAFs at these genes differs from protein-coding gene promoters; TAF5 is present on snRNA genes whereas TAF1, TAF10, and TAF4 are not detected, indicating TAF5 is part of a distinct, snRNA gene-specific TBP/TAF complex.\",\n      \"method\": \"ChIP and siRNA-mediated knockdown\",\n      \"journal\": \"Transcription\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — ChIP combined with siRNA, single lab, single method per TAF\",\n      \"pmids\": [\"22441827\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Cryo-EM structure of human core-TFIID at 11.6 Å resolution reveals a two-fold symmetric, interlaced architecture accommodating TAF4, TAF5, TAF6, TAF9, and TAF12 with their histone folds. TAF5 contributes to this symmetric core. Binding of one TAF8-TAF10 complex breaks the original symmetry, producing an asymmetric scaffold for holo-TFIID assembly.\",\n      \"method\": \"Cryo-electron microscopy (11.6 Å), biochemical reconstitution of core-TFIID subcomplex\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cryo-EM structure combined with biochemical reconstitution, published in high-impact journal with rigorous validation\",\n      \"pmids\": [\"23292512\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Yeast Taf5 is a direct binding target of the Rap1 transcriptional activation domain (AD). Mutation of the newly identified Rap1 AD reduces the efficiency of Rap1 binding to Taf5, confirming Taf5 as a functional coactivator target for Rap1-dependent gene transcription.\",\n      \"method\": \"Altered DNA-binding specificity variant (Rap1AS), in vitro binding assays to Taf5, transcription reporter assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding assay plus functional transcription assay using engineered specificity variant, single lab\",\n      \"pmids\": [\"28196871\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The chaperonin CCT specifically associates with nascent TAF5 in the cytoplasm as a checkpoint for TFIID assembly, facilitating handover of TAF5 to TAF6-TAF9 for subsequent holo-TFIID formation. Structural and mutational analysis of the cytoplasmic TAF5-TAF6-TAF9 submodule identified novel interactions crucial for TFIID integrity and for allocation of TAF9 to either TFIID or the SAGA co-activator complex.\",\n      \"method\": \"Quantitative proteomics, structural analysis, mutagenesis of TAF5-TAF6-TAF9 submodule, co-immunoprecipitation in human cells\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — quantitative proteomics, structural analysis, and mutagenesis combined with cellular assembly assays in one rigorous study\",\n      \"pmids\": [\"30510221\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Cryo-EM structure of promoter-bound yeast TFIID at better than 5 Å resolution reveals that TAF5 and TAF6 form a topologically closed tetramer that stabilizes the compact trilobed architecture of TFIID. This structural analysis confirms unique subunit stoichiometry in TFIID and reveals a hexameric arrangement of histone fold domain-containing TAFs in the Twin lobe.\",\n      \"method\": \"Cryo-electron microscopy (sub-5 Å), cross-linking mass spectrometry, crystal structure docking\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cryo-EM structure combined with cross-linking studies and crystal structure placement, multiple orthogonal methods\",\n      \"pmids\": [\"30405110\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Overexpression of TAF5 (but not TAF9, TAF12, or TBP) suppresses the temperature-sensitive phenotype caused by TAF6 histone-fold domain (HFD) mutations in yeast, revealing a specific genetic and functional relationship between TAF5 and the TAF6 HFD in TFIID assembly and transcriptional activation.\",\n      \"method\": \"Yeast genetic suppression analysis, coimmunoprecipitation from yeast cell extracts\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic suppression combined with Co-IP, single lab, two orthogonal methods\",\n      \"pmids\": [\"29485702\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Cryo-EM structure of yeast SAGA reveals that the core module contains Taf5 (ortholog of human TAF5) along with Sgf73, Spt20, and a histone octamer-like fold. Taf5 and the Taf6 HEAT domain adopt distinct conformations in SAGA compared to TFIID, explaining the functional specialization between these two complexes sharing the same subunit.\",\n      \"method\": \"Cryo-electron microscopy (3.3 Å resolution for core module)\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cryo-EM structure at 3.3 Å for the core module, published in Nature with rigorous structural validation\",\n      \"pmids\": [\"31969703\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"C. elegans TAF-5 (ortholog of human TAF5/TAFII100) is required for a significant fraction of embryonic mRNA transcription as shown by RNAi, but is not essential for expression of multiple developmental and metazoan-specific genes. This phenotype resembles that of TAF-9 and TAF-10 depletion, suggesting TAF-5 is part of a functional module that can be bypassed at many metazoan-specific promoters.\",\n      \"method\": \"RNA interference in C. elegans embryos, RT-PCR analysis of multiple gene targets\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean RNAi in whole organism with multiple gene expression readouts, consistent with companion studies\",\n      \"pmids\": [\"12458202\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"C. elegans taf-5 (human TAFII130 ortholog) is required for essentially all early embryonic mRNA transcription as shown by RNAi, in contrast to taf-10 and taf-11 which have modular functions and can be bypassed at many developmental genes. This suggests a broad structural requirement for TAF-5 in either TFIID or TFTC-like complexes.\",\n      \"method\": \"RNAi in C. elegans embryos, transcriptional analysis of multiple developmental genes\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RNAi with parallel comparison of multiple TAF subunits and multiple gene expression readouts\",\n      \"pmids\": [\"11566890\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Inclusion of the TAF5 alternative exon-8 is required for assembly of the TFIID general transcription initiation complex in human cells; deletion or splice-site mutation of this exon disrupts TFIID assembly and reduces global gene expression output.\",\n      \"method\": \"Massively parallel exon deletion and splice-site mutation CRISPR screens, followed by mechanistic validation of TAF5 exon-8 effect on TFIID assembly and global gene expression\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genome-scale CRISPR screen with in-depth mechanistic follow-up showing TFIID assembly defect and global transcription impact\",\n      \"pmids\": [\"38917794\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Loss of taf5 in zebrafish (nonsense mutation identified by forward genetic screen, confirmed by CRISPR/Cas9) causes craniofacial hypoplasia, ventricular hypoplasia, heart failure, and lethality. taf5-/- zebrafish display misregulation of metabolic gene expression, altered respiration, and metabolite changes, suggesting TAF5 contributes to cardiac and craniofacial development through regulation of metabolism.\",\n      \"method\": \"Forward genetic screen, CRISPR/Cas9 gene editing, RNA sequencing, respiration assays, metabolite studies in zebrafish\",\n      \"journal\": \"Biology open\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockout with multiple orthogonal mechanistic readouts (RNA-seq, respiration, metabolomics), single lab\",\n      \"pmids\": [\"37746814\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Mouse embryos with disrupted Taf5 fail to implant post-blastocyst formation and show aberrant lineage specification within the inner cell mass. Transcriptomic analysis reveals distinct gene targets affected by Taf5 loss compared to Taf12 or Taf13 loss, indicating TAF5 conveys locus specificity to TFIID in early mammalian development.\",\n      \"method\": \"Conditional knockout in mouse, transcriptomic analysis (RNA-seq), immunofluorescence for lineage markers\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean knockout with transcriptomic analysis and immunostaining, single lab, multiple TAF subunits compared in parallel\",\n      \"pmids\": [\"38593904\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In human SAGA, TAF5L (the SAGA-specific paralog of TAF5 that arose by gene duplication in metazoans) adopts structural differences compared to canonical TAF5 that are directly implicated in accommodating the splicing-factor module (SPL). TAF6L's HEAT repeat domain provides a docking surface for SPL, with multiple differences between TAF6L/TAF5L and the canonical TFIID paralogs (TAF5/TAF6) required for this structural re-arrangement.\",\n      \"method\": \"Cryo-EM structure of endogenous human SAGA purified by affinity-ligand (high-resolution structure of SPL and TAF6L HEAT domain)\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — cryo-EM structure with rigorous method, but preprint not yet peer-reviewed and specifically concerns the TAF5L paralog in SAGA rather than TAF5 in TFIID\",\n      \"pmids\": [\"bio_10.1101_2025.07.31.667873\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"TAF5 is an essential ~100 kDa WD-40 repeat-containing subunit of TFIID that forms a flexible N-terminal dimer and serves as a structural scaffold for TFIID assembly: it nucleates a symmetric core subcomplex with TAF4, TAF6, TAF9, and TAF12, is chaperoned by CCT during cytoplasmic assembly before handover to TAF6-TAF9, contains a Rap1-binding domain required for ribosomal protein gene transcription, contributes to a linker domain spanning TFIID lobes, and its alternative exon-8 inclusion is required for functional TFIID assembly and global gene expression; TAF5 also participates in SAGA (via its yeast ortholog Taf5) and can serve as a direct binding target for transcriptional activators and coactivators such as SAYP.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TAF5 is an essential WD-40 repeat-containing subunit of the general transcription factor TFIID that functions principally as a structural scaffold for complex assembly and integrity [#0, #2]. It nucleates a two-fold symmetric core subcomplex with the histone-fold TAFs TAF4, TAF6, TAF9, and TAF12, and RNAi depletion of TAF5 destabilizes TFIID in vivo, defining it as a stability determinant of the complex [#2, #9]. The N-terminal half of TAF5 forms a flexible, extended dimer, and its two copies span the trilobed TFIID architecture, with TAF5 and TAF6 forming a topologically closed tetramer that stabilizes the compact lobed structure and contributes the linker domains connecting lobes [#1, #3, #12]. TAF5 regulates assembly of the TAF6-TAF9 submodule, and its incorporation is gated by the chaperonin CCT, which captures nascent cytoplasmic TAF5 before handing it over to TAF6-TAF9 for holo-TFIID formation [#7, #11]. Beyond its scaffolding role, TAF5 serves as a direct target of transcriptional activators and coactivators: the SAYP coactivator binds TAF5 to couple SWI/SNF chromatin remodeling and TFIID into a supercomplex, and the yeast ortholog contains a Rap1-binding domain required for ribosomal protein gene transcription [#5, #6, #10]. The shared subunit also resides in the SAGA coactivator core, where it adopts a distinct conformation from TFIID [#14]. Functionally, TAF5 is required for the bulk of embryonic mRNA transcription and conveys locus specificity to TFIID during early development, with its loss causing failed implantation in mouse and craniofacial and cardiac defects in zebrafish; inclusion of its alternative exon-8 is required for TFIID assembly and global gene expression in human cells [#16, #17, #18, #19].\",\n  \"teleology\": [\n    {\n      \"year\": 1997,\n      \"claim\": \"Established TAF5 as an integral TFIID subunit with selective interactions among the histone-fold TAFs and a core-promoter-specific function, distinguishing TATA-less from TATA-containing promoter requirements.\",\n      \"evidence\": \"Co-IP and antibody inhibition of in vitro transcription on defined promoters\",\n      \"pmids\": [\"9045704\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve TAF5 architecture within TFIID\", \"Mechanism of promoter selectivity not defined structurally\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Mapped TAF5 within the trilobed TFIID, showing two copies span separate lobes and contribute the inter-lobe linker, establishing its scaffolding geometry.\",\n      \"evidence\": \"EM, immunomapping, and reconstitution of a recombinant TAF5/histone-fold TAF subcomplex in yeast\",\n      \"pmids\": [\"14765106\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Low resolution precluded atomic interactions\", \"Did not define assembly order\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Resolved the TAF5 N-terminal domain structure and demonstrated it forms a flexible extended dimer, identifying a biochemical property required for TFIID assembly.\",\n      \"evidence\": \"X-ray crystallography of NTD2 (2.2 Å) plus biochemical dimerization assays\",\n      \"pmids\": [\"17227857\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of dimerization in cells not tested\", \"Partner contacts of NTD2 clefts unidentified\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Showed TAF5 is a stability determinant of TFIID, contributing to a stable core subcomplex, while having limited direct effect on transcription of tested promoters.\",\n      \"evidence\": \"RNAi knockdown in Drosophila cells with complex-stability and in vitro transcription readouts\",\n      \"pmids\": [\"16895980\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Genome-wide transcriptional impact not assessed\", \"Distinction between scaffolding and direct transcriptional roles unresolved\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identified a Rap1-binding domain in yeast Taf5 required for ribosomal protein gene transcription but dispensable for TFIID integrity, separating an activator-recruitment function from the scaffolding role.\",\n      \"evidence\": \"Domain mutagenesis, in vitro binding, yeast genetics, and gene-specific transcription assays\",\n      \"pmids\": [\"20189987\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether human TAF5 carries an equivalent activator-binding surface unknown\", \"Structural basis of Rap1 contact undefined\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Demonstrated TAF5 is a direct docking target for the SAYP coactivator, coupling SWI/SNF chromatin remodeling to TFIID in an activation-required supercomplex.\",\n      \"evidence\": \"Direct binding, Co-IP, and functional transcription assays in Drosophila\",\n      \"pmids\": [\"19541607\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Binding interface on TAF5 not mapped\", \"Conservation in mammals not shown\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Defined TAF5 as a regulator of TAF6-TAF9 submodule assembly and refined the human core-TFIID architecture, showing TAF5 within a two-fold symmetric core whose symmetry is broken by TAF8-TAF10 binding.\",\n      \"evidence\": \"TAF6C crystal structure, mutagenesis, Co-IP (idx 7) and cryo-EM of core-TFIID with reconstitution (idx 9)\",\n      \"pmids\": [\"22696218\", \"23292512\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Order of TAF5 entry into the assembly pathway not yet established\", \"ChIP-based snRNA-gene and p21 recruitment claims (idx 4, 8) were single-method\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Placed TAF5 at the center of a chaperoned, ordered cytoplasmic assembly pathway, with CCT capturing nascent TAF5 as a checkpoint before handover to TAF6-TAF9, and resolved a TAF5-TAF6 tetramer stabilizing the trilobed TFIID.\",\n      \"evidence\": \"Quantitative proteomics, structural and mutational analysis of the TAF5-TAF6-TAF9 submodule (idx 11), cryo-EM of promoter-bound yeast TFIID with cross-linking MS (idx 12), and yeast genetic suppression (idx 13)\",\n      \"pmids\": [\"30510221\", \"30405110\", \"29485702\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Trigger that releases TAF5 from CCT not defined\", \"How TAF9 is partitioned between TFIID and SAGA mechanistically unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Showed the same Taf5 subunit adopts distinct conformations in SAGA versus TFIID, providing a structural basis for functional specialization of a shared subunit between two coactivator complexes.\",\n      \"evidence\": \"Cryo-EM of yeast SAGA core module (3.3 Å)\",\n      \"pmids\": [\"31969703\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Determinants directing TAF5 to SAGA versus TFIID not identified\", \"Human SAGA-specific paralog relationships addressed only later (idx 20, preprint)\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Connected TAF5 to organismal phenotypes and locus-specific transcription, showing it is required for early embryonic transcription, conveys locus specificity in mammalian development, and that its alternative exon-8 is required for TFIID assembly and global expression.\",\n      \"evidence\": \"C. elegans/mouse RNAi and conditional knockout with RNA-seq (idx 16, 19), zebrafish forward-genetic knockout with metabolomics (idx 18), and CRISPR exon-deletion screens with mechanistic validation in human cells (idx 17)\",\n      \"pmids\": [\"11566890\", \"38593904\", \"37746814\", \"38917794\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis of locus specificity conferred by TAF5 not defined\", \"Whether developmental phenotypes reflect TFIID assembly defects versus selective gene targets unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How TAF5 mechanistically directs promoter and locus selectivity within TFIID, and what governs its release from CCT and partitioning between TFIID and SAGA, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model linking TAF5 conformation to gene-specific output\", \"CCT-release trigger unknown\", \"Human activator-binding surface analogous to yeast Rap1-binding domain not defined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [1, 2, 3, 9, 12]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [5, 11]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 6, 17]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 4]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [11]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 2, 17]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [18, 19]}\n    ],\n    \"complexes\": [\"TFIID\", \"SAGA\", \"core-TFIID (TAF5-TAF6-TAF9-TAF4-TAF12)\", \"BTFly supercomplex\"],\n    \"partners\": [\"TAF6\", \"TAF9\", \"TAF4\", \"TAF12\", \"CCT\", \"SAYP\", \"Rap1\", \"TBP\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}