{"gene":"TADA3","run_date":"2026-04-28T21:42:58","timeline":{"discoveries":[{"year":1993,"finding":"ADA3 (NGG1) was identified as a gene whose mutation prevents GAL4-VP16 toxicity and reduces transactivation by VP16 and GCN4 acidic activation domains; double disruption of ada2 and ada3 shows no additive growth defect, placing them in the same pathway.","method":"Genetic screen, gene disruption, epistasis analysis (double mutant), in vitro transcription initiation assay","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis with defined phenotypic readout, replicated in multiple mutant backgrounds","pmids":["8413201"],"is_preprint":false},{"year":1995,"finding":"Ada2, Ada3, and Gcn5 form a heterotrimeric complex in vitro, with Ada2 as the linchpin holding Ada3 and Gcn5 together; Ada3 has two separable domains, with the C-terminal domain sufficient for complex formation and the N-terminal domain proposed to mediate interaction with activation domains.","method":"In vitro pulldown/reconstitution, deletion analysis, in vivo LexA fusion activation assays","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1-2 — reconstitution in vitro plus in vivo functional assays with domain dissection","pmids":["7862114"],"is_preprint":false},{"year":1997,"finding":"NGG1p/ADA3p and ADA2p are coimmunoprecipitated from yeast whole cell extracts, are present in at least four native complexes of different sizes (>2 MDa, ~900 kDa, ~200 kDa), and the complex associates with TBP; this TBP interaction requires residues 274–307 of NGG1p.","method":"Co-immunoprecipitation from yeast extracts, ion-exchange chromatography, gel-filtration chromatography, deletion analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP from native extracts with domain mapping, replicated across multiple chromatographic methods","pmids":["9038164"],"is_preprint":false},{"year":2001,"finding":"Yeast Ada2, Ada3, and Gcn5 form the catalytic core of ADA and SAGA HAT complexes that is necessary and sufficient in vitro for nucleosomal HAT activity and lysine specificity; Ada3 is required for Gcn5-dependent nucleosomal HAT activity and facilitates an expanded lysine specificity, while Ada2 potentiates Gcn5 catalytic activity.","method":"In vitro reconstitution of catalytic core, nucleosomal HAT activity assays, yeast extract-based HAT assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution with functional HAT assay on nucleosomal substrate","pmids":["11773077"],"is_preprint":false},{"year":2001,"finding":"hADA3 physically interacts with p53 in human cells; this interaction is enhanced after DNA damage due to phosphorylation events in the p53 N-terminus; hADA3 is required for full transcriptional activity of p53 and p53-mediated apoptosis.","method":"Yeast p53 dissociator assay, co-immunoprecipitation from human cells, DNA damage experiments, transcriptional reporter assays, apoptosis assays","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (yeast assay, Co-IP, functional transcription, apoptosis) in single study","pmids":["11707411"],"is_preprint":false},{"year":2002,"finding":"hADA3 is a novel interacting partner and target of HPV16 E6 oncoprotein; E6 induces hADA3 degradation; hADA3 functions as a coactivator for p53-mediated transactivation by stabilizing p53; E6 mutants that do not degrade p53 but do interact with hADA3 still abrogate p53-mediated transactivation and G1 arrest after DNA damage.","method":"Co-immunoprecipitation, protein degradation assays, transcriptional reporter assays, cell cycle analysis (G1 arrest), use of E6 mutants","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods, mechanistic dissection with E6 mutant panel","pmids":["12138191"],"is_preprint":false},{"year":2002,"finding":"hADA3 directly binds RXRα in vitro and in vivo, is recruited to native RXR response elements in the p21 promoter (by ChIP), and enhances RXRα-mediated transactivation of retinoid target genes; HPV E6 inhibits this RXR-mediated transactivation by targeting hADA3.","method":"GST pulldown (in vitro binding), co-immunoprecipitation, chromatin immunoprecipitation (ChIP), transcriptional reporter assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — direct binding confirmed in vitro and in vivo, ChIP for endogenous promoter occupancy, functional reporter assays","pmids":["12235159"],"is_preprint":false},{"year":2002,"finding":"ADA3-containing TFTC complex interacts with ERα in a ligand-independent manner; mouse mADA3 does not directly interact with nuclear receptors despite containing LxxLL NR boxes, indicating other TFTC subunits mediate the receptor interaction.","method":"Cloning of mouse ADA3, co-immunoprecipitation, interaction assays with ERα","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP from native complex, direct binding tested, but interaction attributed to other complex subunits","pmids":["12034840"],"is_preprint":false},{"year":2004,"finding":"hADA3 directly interacts with ERα and ERβ in vitro and in vivo; hADA3 is a component of activator complexes bound to the native ER response element in the pS2 promoter; endogenous hADA3 is required for ER-mediated transactivation and estrogen-induced target gene expression; HPV E6 targeting of hADA3 inhibits ERα-mediated transactivation.","method":"GST pulldown, co-immunoprecipitation, ChIP, luciferase reporter assay, RT-PCR for endogenous ER target genes, RNA interference (siRNA knockdown of ADA3)","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — direct binding in vitro and in vivo, endogenous ChIP, RNAi functional validation with multiple orthogonal methods","pmids":["15496419"],"is_preprint":false},{"year":2007,"finding":"Endogenous hAda3 stabilizes p53 protein by promoting its acetylation at p300/CBP acetylation sites; hAda3 is required for DNA damage-induced p53 acetylation, stabilization, and target gene induction; acetylation-defective p53 mutants fail to show hAda3-dependent stabilization.","method":"Inducible overexpression and shRNA knockdown of hAda3, western blot for p53 acetylation, p53 mutant analysis, target gene expression assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple genetic approaches (OE, shRNA, acetylation site mutant), mechanistically defined pathway","pmids":["17272277"],"is_preprint":false},{"year":2007,"finding":"hAda3 is required for p14ARF-induced p53 acetylation and cellular senescence; the N-terminal domain of hAda3 binds p53 but not p300, and its expression blocks p14ARF-induced p53 acetylation and senescence; hAda3 promotes p300-mediated p53 acetylation and siRNA knockdown of hAda3 inhibits endogenous p53 acetylation and p21 accumulation.","method":"Dominant-negative N-terminal domain expression, siRNA knockdown, p300-mediated acetylation assay, senescence assay, western blot","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 — domain dissection, siRNA functional validation, mechanistic link to p300-mediated acetylation","pmids":["17452980"],"is_preprint":false},{"year":2007,"finding":"Ada3, ERα, and three distinct HATs (p300, PCAF, and Gcn5) co-sediment in a complex (glycerol gradient) and co-immunoprecipitate; Ada3 is required for ligand-dependent recruitment of p300, PCAF, and Gcn5 to the ER-responsive pS2 promoter; Ada3 is critical for estrogen-dependent proliferation of ER-positive breast cancer cells.","method":"Glycerol gradient cosedimentation, co-immunoprecipitation, ChIP, shRNA knockdown, 2D and 3D cell proliferation assays","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 2 — complex formation confirmed by two methods, ChIP for promoter recruitment, shRNA functional validation","pmids":["18089809"],"is_preprint":false},{"year":2007,"finding":"Drosophila dADA3 localizes to chromosomes and is significantly reduced in dGcn5 and dAda2a mutant backgrounds; dAda3 loss reduces acetylation at H3K9, H3K14, H4K12, and phosphorylation at H3S10; dAda3 is required for oogenesis and somatic cell viability.","method":"Immunofluorescence (localization), genetic mutant analysis, western blot for histone modifications, position effect variegation assays","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 — direct localization on chromosomes, genetic epistasis with other SAGA subunits, specific histone mark analysis","pmids":["17967867"],"is_preprint":false},{"year":2007,"finding":"hADA2a and hADA3 physically interact with beta-catenin through Armadillo repeats 6–12 and the C-terminal transactivation domain; both reside with beta-catenin at the c-Myc enhancer; RNAi-mediated reduction of hADA2a and hADA3 results in reduced beta-catenin acetylation, reduced reporter activity, and reduced Wnt target gene activation and proliferation.","method":"Co-immunoprecipitation, domain deletion analysis, ChIP, siRNA knockdown, luciferase reporter assay, RT-PCR for endogenous target genes","journal":"Cancer biology & therapy","confidence":"High","confidence_rationale":"Tier 2 — direct interaction with domain mapping, ChIP, and functional siRNA knockdown","pmids":["18059173"],"is_preprint":false},{"year":2008,"finding":"ANCO-1 and ANCO-2 interact with hADA3; the interaction occurs between the conserved C-terminal domain of ANCO-1 and the N-terminal transactivation domain of ADA3; ANCO-1 co-localizes with ADA3, ADA2α/β, and PCAF at nuclear dots; ANCO-1/2 repress ADA3-mediated transcriptional co-activation on nuclear receptors.","method":"Co-immunoprecipitation, domain deletion analysis, immunofluorescence co-localization, transcriptional reporter assay","journal":"The Biochemical journal","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP with domain mapping and co-localization, functional reporter assay, but single lab study","pmids":["18377363"],"is_preprint":false},{"year":2010,"finding":"Human ADA3 interacts directly with RARα in a hormone-dependent manner through LxxLL motifs in hADA3 and the coactivator pocket of RARα; loss- and gain-of-function mutations in LxxLL motifs alter this interaction; hADA3 associates with RARα target gene promoters in a hormone-dependent manner; ADA3 knockdown impairs RARβ2 expression.","method":"Co-immunoprecipitation, LxxLL motif mutagenesis (loss/gain of function), ChIP, RT-PCR for endogenous target genes, structural modeling","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1-2 — direct binding with mutagenesis, ChIP on endogenous promoter, functional gene expression readout","pmids":["20413580"],"is_preprint":false},{"year":2012,"finding":"Germline deletion of Ada3 in mouse causes embryonic lethality; conditional deletion in MEFs causes severe proliferation defect rescued by human Ada3; Ada3 deletion causes G1-to-S delay due to accumulation of CDK inhibitor p27 as an indirect consequence of reduced c-Myc transcription; Ada3 loss causes global histone acetylation changes, abnormal nuclei, mitotic defects, and delayed G2/M-to-G1 transition.","method":"Germline knockout (Ada3 null mouse), adenovirus-Cre conditional deletion in MEFs, cell cycle analysis (FACS), ectopic rescue with human Ada3, siRNA knockdown of p27, microarray gene expression analysis, immunofluorescence","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — clean KO with defined phenotypic readout, rescue experiment, epistasis with p27 knockdown","pmids":["22736770"],"is_preprint":false},{"year":2012,"finding":"Ada3 deletion leads to enhanced chromosomal aberrations (breaks, fragments, deletions, translocations) and delayed clearance of DNA damage foci (pATM, γH2AX, p53BP1, pRAD51) after ionizing radiation, demonstrating a role in DNA damage response and genomic stability maintenance.","method":"Adenovirus-Cre conditional deletion in Ada3fl/fl MEFs, immunofluorescence for DNA damage foci, chromosomal aberration analysis, comet assay","journal":"Cell cycle (Georgetown, Tex.)","confidence":"High","confidence_rationale":"Tier 2 — clean conditional KO, multiple DNA repair markers, cytogenetics","pmids":["23095635"],"is_preprint":false},{"year":2013,"finding":"hADA3 interacts with AATF (apoptosis-antagonizing transcription factor), PPP1R7 (PP1 regulatory subunit 7), and PPP2R5D (PP2A regulatory subunit δ) as novel binding partners; interaction with these partners does not require the C-terminal ADA2-interacting domain of hADA3; expression of these interacting proteins alters hADA3-regulated reporter gene activity.","method":"Yeast two-hybrid screen of human cDNA library, co-immunoprecipitation, immunofluorescence co-localization, truncation analysis, reporter gene assay","journal":"The Biochemical journal","confidence":"Medium","confidence_rationale":"Tier 3 — yeast two-hybrid plus Co-IP validation, functional reporter assay, but single lab study","pmids":["23167988"],"is_preprint":false},{"year":2014,"finding":"PCAF and ADA3 regulate granzyme B-mediated apoptosis upstream of mitochondrial permeabilization; PCAF or ADA3 knockdown reduces Bid cleavage and PACS2 expression; PACS2 knockdown phenocopies PCAF/ADA3 knockdown, defining a PCAF/ADA3→PACS2→Bid pathway for mitochondrial apoptosis.","method":"shRNAmiR functional genomic screen, siRNA knockdown validation, cytochrome c release assay, Bid cleavage assay, PACS2 expression analysis","journal":"Cell death and differentiation","confidence":"High","confidence_rationale":"Tier 2 — unbiased screen followed by independent siRNA validation, genetic epistasis via PACS2 knockdown phenocopy","pmids":["24464226"],"is_preprint":false},{"year":2014,"finding":"HPV16 E6 targets hADA3 for ubiquitin-mediated degradation via E6AP ubiquitin ligase; hADA3 undergoes SUMOylation that is accelerated by HPV16 E6 and makes hADA3 unstable; Ubc9 depletion prevents rapid E6-mediated hADA3 degradation, revealing a SUMOylation-ubiquitination coupling mechanism.","method":"Ubiquitination assay, SUMOylation assay, siRNA knockdown of E6AP and Ubc9, western blot, protein stability assays","journal":"Carcinogenesis","confidence":"High","confidence_rationale":"Tier 2 — mechanistically defined PTM pathway with genetic perturbation of individual enzymes","pmids":["24795430"],"is_preprint":false},{"year":2015,"finding":"ADA3 associates with the α-satellite repeat region of human X chromosome centromeres; ADA3 physically associates with CENP-B through its N-terminus (confirmed by proximity ligation assay and immunofluorescence); an ADA3 mutant unable to bind CENP-B fails to rescue cell proliferation; ADA3 is required for loading CENP-B onto centromeres; Ada3 deletion causes chromosome segregation defects.","method":"Proximity ligation assay, immunofluorescence, ChIP on centromeric sequences, deletion analysis, CENP-B binding-deficient mutant rescue assay, cytogenetic analysis of chromosome segregation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal localization and interaction methods, functional mutant rescue, phenotypic validation","pmids":["26429915"],"is_preprint":false},{"year":2016,"finding":"ADA3 acetylation is dynamically regulated in a cell cycle-dependent manner by HATs GCN5, PCAF, and p300, and is reversed by SIRT1; mass spectrometry and site-directed mutagenesis identified major acetylation sites; acetylation-defective ADA3 mutants associate with HATs and HAT complex components but fail to restore global or locus-specific histone acetylation marks or cell proliferation in Ada3-deleted MEFs.","method":"Mass spectrometry to identify acetylation sites, site-directed mutagenesis, inducible expression in Ada3-deleted MEFs, rescue assay, HAT activity assays, co-immunoprecipitation","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1-2 — mass spectrometry identification, mutagenesis functional validation, rescue in KO cells","pmids":["27402865"],"is_preprint":false},{"year":2017,"finding":"EGFR/HER2 signaling through AKT promotes phosphorylation of p300, which in turn promotes ADA3 acetylation; inhibition of HER1/HER2 by lapatinib reduces phospho-AKT, p300 phosphorylation, and ADA3 protein levels; ADA3 acetylation competes with ubiquitination on shared lysine residues to regulate ADA3 stability; ADA3 knockdown mimics lapatinib-induced cell cycle inhibition and apoptosis.","method":"RTK inhibitor (lapatinib) treatment, AKT inhibition, p300/PCAF inhibitor (garcinol), acetylation-defective ADA3 mutants (K→R), protein stability (half-life) assays, cell cycle analysis","journal":"Cell cycle (Georgetown, Tex.)","confidence":"High","confidence_rationale":"Tier 2 — pharmacological and genetic perturbation of each signaling node, mechanistic competition between acetylation and ubiquitination defined by mutant analysis","pmids":["28759294"],"is_preprint":false}],"current_model":"TADA3 (ADA3/NGG1) is an essential scaffolding subunit of the Ada2/Ada3/Gcn5 catalytic HAT module within SAGA and related megadalton coactivator complexes, where it facilitates nucleosomal histone acetylation (H3K9/K14, H4K12) by Gcn5 and expanded lysine specificity; it directly interacts with transcription factors including p53, ERα, RXRα, RARα, and β-catenin to recruit HATs (p300, PCAF, Gcn5) to target promoters, stabilizes p53 through promoting its p300-mediated acetylation after DNA damage, associates with centromere protein CENP-B to support proper chromosome segregation, and is itself regulated by dynamic acetylation (by GCN5/PCAF/p300, reversed by SIRT1) downstream of EGFR-AKT-p300 signaling, with HPV16 E6 targeting hADA3 for SUMOylation-coupled ubiquitin/E6AP-mediated degradation to perturb multiple tumor suppressor pathways."},"narrative":{"teleology":[{"year":1993,"claim":"Establishing that ADA3 functions in the same transcriptional coactivation pathway as ADA2 resolved a key question about whether multiple ADA genes act in parallel or sequential steps, placing ADA3 as a core component of an adaptor complex linking acidic activation domains to the transcription machinery.","evidence":"Genetic screen for GAL4-VP16 toxicity suppressors and double-mutant epistasis analysis in yeast","pmids":["8413201"],"confidence":"High","gaps":["Biochemical nature of the ADA2–ADA3 interaction not yet defined","No enzymatic activity assigned to ADA3"]},{"year":1995,"claim":"Reconstituting the Ada2/Ada3/Gcn5 heterotrimer in vitro and mapping Ada3 domain architecture answered how these three proteins physically assemble, revealing Ada2 as the linchpin and identifying separable N- and C-terminal functional domains in Ada3.","evidence":"In vitro pulldown/reconstitution with recombinant proteins, deletion analysis, LexA fusion activation assays in yeast","pmids":["7862114"],"confidence":"High","gaps":["Whether the heterotrimer is sufficient for HAT activity was unknown","Identity of in vivo native complexes containing Ada3 not resolved"]},{"year":1997,"claim":"Demonstrating that Ada3/Ada2 reside in multiple native complexes of distinct sizes (>2 MDa, ~900 kDa, ~200 kDa) and interact with TBP established that Ada3 functions within megadalton coactivator assemblies that directly contact basal transcription machinery.","evidence":"Co-immunoprecipitation from yeast extracts, gel-filtration and ion-exchange chromatography, domain deletion mapping of TBP interaction","pmids":["9038164"],"confidence":"High","gaps":["Composition of the distinct complexes not fully defined","Functional distinction between the different-sized complexes unclear"]},{"year":2001,"claim":"Reconstituting the Ada2/Ada3/Gcn5 trimeric core as necessary and sufficient for nucleosomal HAT activity definitively established Ada3 as an essential enabler of Gcn5-mediated chromatin acetylation with expanded lysine specificity, answering why Ada3 loss abolishes histone acetylation in vivo.","evidence":"In vitro reconstitution of catalytic core, nucleosomal HAT assays with recombinant and native complexes","pmids":["11773077"],"confidence":"High","gaps":["Structural basis of how Ada3 alters Gcn5 substrate specificity unknown","Whether mammalian ADA3 functions identically in HAT module not tested"]},{"year":2001,"claim":"Identifying hADA3 as a physical interactor and functional coactivator of p53 that is enhanced by DNA damage-induced phosphorylation revealed the first direct link between the SAGA adaptor module and a mammalian tumor suppressor.","evidence":"Yeast p53 dissociator assay, co-immunoprecipitation from human cells, DNA damage experiments, transcriptional reporters, apoptosis assays","pmids":["11707411"],"confidence":"High","gaps":["Mechanism by which hADA3 promotes p53 transcriptional output not defined","Whether HAT activity is required for p53 coactivation unknown"]},{"year":2002,"claim":"Showing that HPV16 E6 targets hADA3 for degradation and that E6 mutants unable to degrade p53 but able to target hADA3 still abrogate p53 function established hADA3 as an independent viral target whose loss is sufficient to disable p53-mediated tumor suppression.","evidence":"Co-immunoprecipitation, protein degradation assays, E6 mutant panel, cell cycle analysis","pmids":["12138191"],"confidence":"High","gaps":["Degradation pathway (ubiquitin ligase identity, PTM requirements) not defined","Whether E6 targets hADA3 in patient-derived HPV-positive cells not shown"]},{"year":2002,"claim":"Demonstrating that hADA3 directly binds RXRα and is recruited to retinoid response elements expanded the coactivator function of TADA3 beyond p53 to nuclear receptors, establishing it as a general transcription factor adaptor.","evidence":"GST pulldown, co-immunoprecipitation, ChIP on p21 promoter, transcriptional reporter assays","pmids":["12235159"],"confidence":"High","gaps":["Whether hADA3 directly contacts RXRα or does so through an intermediary in the full complex was debated (cf. PMID:12034840)","Structural basis of receptor recognition unknown"]},{"year":2004,"claim":"Confirming direct hADA3–ERα/ERβ interaction and showing that endogenous hADA3 is required for estrogen-dependent target gene expression resolved the question of whether hADA3 serves as a bona fide nuclear receptor coactivator for estrogen signaling.","evidence":"GST pulldown, co-immunoprecipitation, ChIP on pS2 promoter, siRNA knockdown, RT-PCR for endogenous targets","pmids":["15496419"],"confidence":"High","gaps":["Whether hADA3 interaction with ERα is direct in the context of intact SAGA/ATAC not clarified","Contribution to ER-driven oncogenesis not tested in vivo"]},{"year":2007,"claim":"Mechanistically linking hADA3 to p53 stabilization through p300-mediated acetylation and ARF-induced senescence resolved how hADA3 promotes p53 function: by serving as a scaffold that facilitates p300-dependent p53 acetylation, which prevents p53 degradation.","evidence":"Overexpression and shRNA knockdown of hAda3, p53 acetylation site mutants, p14ARF-induced senescence assays, dominant-negative N-terminal domain","pmids":["17272277","17452980"],"confidence":"High","gaps":["Whether hADA3 directly bridges p53 and p300 or acts through additional intermediaries not distinguished","In vivo tumor suppressor role not validated"]},{"year":2007,"claim":"Showing that Ada3 co-sediments with ERα and three distinct HATs (p300, PCAF, Gcn5) and is required for their ligand-dependent promoter recruitment established Ada3 as the central hub coordinating multiple HATs at hormone-responsive genes.","evidence":"Glycerol gradient cosedimentation, co-immunoprecipitation, ChIP, shRNA knockdown, proliferation assays in ER-positive breast cancer cells","pmids":["18089809"],"confidence":"High","gaps":["Stoichiometry of the multi-HAT complex undefined","Whether Ada3 bridges HATs simultaneously or sequentially unclear"]},{"year":2007,"claim":"Drosophila genetic analysis showed that dADA3 localizes to chromosomes, depends on dGcn5/dAda2a for stability, and is required for H3K9/K14 and H4K12 acetylation, confirming evolutionary conservation of Ada3's HAT-enabling function from yeast to metazoans.","evidence":"Immunofluorescence on polytene chromosomes, genetic mutant analysis, western blot for histone marks in Drosophila","pmids":["17967867"],"confidence":"High","gaps":["Whether Drosophila Ada3 also serves as a transcription factor adaptor not tested","Target gene specificity not addressed"]},{"year":2007,"claim":"Discovering that hADA3 interacts with β-catenin at the c-Myc enhancer and is required for Wnt target gene activation extended TADA3 function to the Wnt signaling pathway, beyond nuclear receptor and p53 programs.","evidence":"Co-immunoprecipitation with domain mapping, ChIP at c-Myc enhancer, siRNA knockdown, RT-PCR for Wnt targets","pmids":["18059173"],"confidence":"High","gaps":["Whether β-catenin acetylation by TADA3-associated HATs has functional consequences in vivo unclear","Specificity versus other TCF/LEF coactivators not assessed"]},{"year":2010,"claim":"Identifying LxxLL motifs in hADA3 as mediating hormone-dependent direct interaction with the RARα coactivator pocket answered how TADA3 physically recognizes nuclear receptors and established a general structural mechanism for its adaptor function.","evidence":"LxxLL motif mutagenesis (loss and gain of function), co-immunoprecipitation, ChIP on RARβ2 promoter, endogenous target gene expression","pmids":["20413580"],"confidence":"High","gaps":["Crystal structure of ADA3 LxxLL–receptor interface not solved","Whether different LxxLL motifs specify different receptor interactions not fully resolved"]},{"year":2012,"claim":"Mouse knockout studies established that Ada3 is essential for embryonic development and cell proliferation, with deletion causing G1/S delay via p27 accumulation (due to reduced c-Myc), global histone acetylation loss, mitotic defects, chromosomal aberrations, and impaired DNA damage repair, consolidating Ada3 as essential for genome integrity.","evidence":"Germline Ada3 knockout, conditional deletion in MEFs, FACS cell cycle analysis, human Ada3 rescue, cytogenetics, DNA damage foci kinetics","pmids":["22736770","23095635"],"confidence":"High","gaps":["Tissue-specific roles in adult mouse not explored","Whether DNA repair defect is direct or secondary to chromatin acetylation loss unclear"]},{"year":2014,"claim":"Defining the SUMOylation–ubiquitination coupling mechanism for HPV16 E6-mediated hADA3 degradation via E6AP resolved a longstanding question about the degradation pathway and revealed that SUMOylation primes hADA3 for ubiquitin-dependent destruction.","evidence":"Ubiquitination and SUMOylation assays, siRNA knockdown of E6AP and Ubc9, protein stability assays","pmids":["24795430"],"confidence":"High","gaps":["SUMO acceptor lysine sites on hADA3 not mapped","Whether this mechanism operates for other E6 targets unknown"]},{"year":2014,"claim":"Identifying a PCAF/ADA3→PACS2→Bid pathway for granzyme B-induced mitochondrial apoptosis revealed a non-transcriptional role for the PCAF/ADA3 module in immune cell-mediated killing.","evidence":"shRNAmiR functional genomic screen, independent siRNA validation, cytochrome c release and Bid cleavage assays, PACS2 epistasis","pmids":["24464226"],"confidence":"High","gaps":["Whether ADA3's role in this pathway requires its HAT-scaffolding function not tested","In vivo relevance to anti-tumor immunity not established"]},{"year":2015,"claim":"Discovering that ADA3 physically associates with CENP-B at centromeres and is required for CENP-B loading and proper chromosome segregation revealed an unexpected centromeric function beyond transcriptional coactivation.","evidence":"Proximity ligation assay, immunofluorescence, ChIP on α-satellite sequences, CENP-B binding-deficient ADA3 mutant rescue, cytogenetics","pmids":["26429915"],"confidence":"High","gaps":["Whether centromeric function involves local histone acetylation not determined","Structural basis of ADA3–CENP-B interaction not solved"]},{"year":2016,"claim":"Demonstrating that ADA3 itself is dynamically acetylated by GCN5/PCAF/p300 and deacetylated by SIRT1, and that acetylation-defective ADA3 mutants fail to restore histone acetylation or proliferation, established that ADA3 acetylation is a regulatory switch controlling its HAT complex function.","evidence":"Mass spectrometry for acetylation sites, site-directed mutagenesis, functional rescue in Ada3-deleted MEFs, co-immunoprecipitation","pmids":["27402865"],"confidence":"High","gaps":["How acetylation mechanistically alters ADA3 function (conformational change, binding affinity) undefined","Cell cycle-dependent regulation mechanism not elucidated"]},{"year":2017,"claim":"Placing ADA3 acetylation downstream of EGFR–AKT–p300 signaling and showing that acetylation competes with ubiquitination on shared lysine residues to control ADA3 stability connected growth factor signaling to chromatin acetylation through a post-translational switch on ADA3.","evidence":"RTK inhibitor (lapatinib) and AKT inhibitor treatment, acetylation-defective K→R mutants, protein half-life assays, cell cycle analysis","pmids":["28759294"],"confidence":"High","gaps":["Identity of the E3 ubiquitin ligase targeting ADA3 under normal (non-HPV) conditions unknown","In vivo validation of EGFR–ADA3 axis in tumors lacking"]},{"year":null,"claim":"Key unresolved questions include the structural basis by which ADA3 enables Gcn5 nucleosomal substrate recognition and expanded lysine specificity, whether ADA3's centromeric and DNA damage repair functions are mechanistically separable from its HAT-scaffolding role, and identification of the physiological E3 ligase controlling ADA3 turnover in the absence of viral oncoproteins.","evidence":"","pmids":[],"confidence":"Low","gaps":["No high-resolution structure of ADA3 in the HAT module context","Centromeric versus transcriptional functions not genetically separated","Physiological E3 ubiquitin ligase for ADA3 unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,4,6,8,11,15]},{"term_id":"GO:0042393","term_label":"histone binding","supporting_discovery_ids":[3,12,22]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,4,8,13,15]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[12,14,21]},{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[12,21]}],"pathway":[{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[3,12,16,22]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,4,8,11,13,15]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[16,21]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[17]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[4,19]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[13,23]}],"complexes":["SAGA complex","ADA complex","TFTC/STAGA complex","Ada2/Ada3/Gcn5 HAT module"],"partners":["GCN5","TADA2A","TADA2B","TP53","EP300","PCAF","CENPB","CTNNB1"],"other_free_text":[]},"mechanistic_narrative":"TADA3 (ADA3/NGG1) is an essential scaffolding subunit of the Ada2/Ada3/Gcn5 histone acetyltransferase (HAT) catalytic module within SAGA-type coactivator complexes, where it enables Gcn5-dependent nucleosomal histone acetylation at H3K9, H3K14, and H4K12 and expands Gcn5 lysine specificity [PMID:11773077, PMID:17967867]. Beyond its core HAT-enabling role, TADA3 functions as a transcriptional coactivator adaptor that directly recruits HATs (p300, PCAF, Gcn5) to promoters occupied by transcription factors including p53, ERα, RARα, RXRα, and β-catenin, thereby coupling activator-dependent gene expression programs to chromatin acetylation [PMID:15496419, PMID:18089809, PMID:20413580, PMID:18059173]. TADA3 stabilizes p53 by promoting its p300-mediated acetylation following DNA damage, is required for DNA damage response fidelity and chromosome segregation through interaction with centromeric CENP-B, and its own stability is regulated by acetylation–ubiquitination competition on shared lysine residues downstream of EGFR–AKT–p300 signaling [PMID:17272277, PMID:23095635, PMID:26429915, PMID:28759294]. HPV16 E6 oncoprotein subverts multiple TADA3-dependent tumor-suppressive pathways by targeting TADA3 for SUMOylation-coupled E6AP-mediated ubiquitin-proteasomal degradation [PMID:24795430, PMID:12138191]."},"prefetch_data":{"uniprot":{"accession":"O75528","full_name":"Transcriptional adapter 3","aliases":["ADA3 homolog","hADA3","STAF54","Transcriptional adapter 3-like","ADA3-like protein"],"length_aa":432,"mass_kda":48.9,"function":"Functions as a component of the PCAF complex. The PCAF complex is capable of efficiently acetylating histones in a nucleosomal context. The PCAF complex could be considered as the human version of the yeast SAGA complex. Also known as a coactivator for p53/TP53-dependent transcriptional activation. Component of the ATAC complex, a complex with histone acetyltransferase activity on histones H3 and H4","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/O75528/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TADA3","classification":"Not Classified","n_dependent_lines":451,"n_total_lines":1208,"dependency_fraction":0.37334437086092714},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"TAF12","stoichiometry":10.0},{"gene":"TRRAP","stoichiometry":10.0},{"gene":"ACTB","stoichiometry":0.2},{"gene":"ENY2","stoichiometry":0.2},{"gene":"SF3B3","stoichiometry":0.2},{"gene":"SF3B5","stoichiometry":0.2},{"gene":"TBP","stoichiometry":0.2},{"gene":"USP22","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/TADA3","total_profiled":1310},"omim":[{"mim_id":"617501","title":"LYSINE ACETYLTRANSFERASE 14; KAT14","url":"https://www.omim.org/entry/617501"},{"mim_id":"613373","title":"YEATS DOMAIN-CONTAINING PROTEIN 2; YEATS2","url":"https://www.omim.org/entry/613373"},{"mim_id":"602945","title":"TRANSCRIPTIONAL ADAPTOR 3; TADA3","url":"https://www.omim.org/entry/602945"},{"mim_id":"602303","title":"LYSINE ACETYLTRANSFERASE 2B; KAT2B","url":"https://www.omim.org/entry/602303"},{"mim_id":"602301","title":"LYSINE ACETYLTRANSFERASE 2A; KAT2A","url":"https://www.omim.org/entry/602301"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/TADA3"},"hgnc":{"alias_symbol":["FLJ20221","FLJ21329","ADA3","hADA3","NGG1"],"prev_symbol":["TADA3L"]},"alphafold":{"accession":"O75528","domains":[{"cath_id":"-","chopping":"18-75_342-428","consensus_level":"medium","plddt":92.9828,"start":18,"end":428}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O75528","model_url":"https://alphafold.ebi.ac.uk/files/AF-O75528-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O75528-F1-predicted_aligned_error_v6.png","plddt_mean":75.44},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TADA3","jax_strain_url":"https://www.jax.org/strain/search?query=TADA3"},"sequence":{"accession":"O75528","fasta_url":"https://rest.uniprot.org/uniprotkb/O75528.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O75528/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O75528"}},"corpus_meta":[{"pmid":"11773077","id":"PMC_11773077","title":"Role of the Ada2 and Ada3 transcriptional coactivators in histone acetylation.","date":"2001","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/11773077","citation_count":190,"is_preprint":false},{"pmid":"7862114","id":"PMC_7862114","title":"ADA3, a putative transcriptional adaptor, consists of two separable domains and interacts with ADA2 and GCN5 in a trimeric complex.","date":"1995","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/7862114","citation_count":158,"is_preprint":false},{"pmid":"12138191","id":"PMC_12138191","title":"Human papillomavirus oncoprotein E6 inactivates the transcriptional coactivator human ADA3.","date":"2002","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/12138191","citation_count":114,"is_preprint":false},{"pmid":"9038164","id":"PMC_9038164","title":"Identification of native complexes containing the yeast coactivator/repressor proteins NGG1/ADA3 and ADA2.","date":"1997","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9038164","citation_count":105,"is_preprint":false},{"pmid":"8413201","id":"PMC_8413201","title":"ADA3: a gene, identified by resistance to GAL4-VP16, with properties similar to and different from those of ADA2.","date":"1993","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/8413201","citation_count":102,"is_preprint":false},{"pmid":"9154821","id":"PMC_9154821","title":"ADA1, a novel component of the ADA/GCN5 complex, has broader effects than GCN5, ADA2, or ADA3.","date":"1997","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/9154821","citation_count":93,"is_preprint":false},{"pmid":"11707411","id":"PMC_11707411","title":"hADA3 is required for p53 activity.","date":"2001","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/11707411","citation_count":66,"is_preprint":false},{"pmid":"12235159","id":"PMC_12235159","title":"Human papilloma virus 16 E6 oncoprotein inhibits retinoic X receptor-mediated transactivation by targeting human ADA3 coactivator.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12235159","citation_count":53,"is_preprint":false},{"pmid":"8262068","id":"PMC_8262068","title":"Characterization of NGG1, a novel yeast gene required for glucose repression of GAL4p-regulated transcription.","date":"1993","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/8262068","citation_count":47,"is_preprint":false},{"pmid":"17272277","id":"PMC_17272277","title":"An essential role of human Ada3 in p53 acetylation.","date":"2007","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/17272277","citation_count":40,"is_preprint":false},{"pmid":"32890768","id":"PMC_32890768","title":"The Ada2/Ada3/Gcn5/Sgf29 histone acetyltransferase module.","date":"2020","source":"Biochimica et biophysica acta. 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Factor Receptor activation promotes ADA3 acetylation through the AKT-p300 pathway.","date":"2017","source":"Cell cycle (Georgetown, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/28759294","citation_count":15,"is_preprint":false},{"pmid":"27402865","id":"PMC_27402865","title":"Acetylation of Mammalian ADA3 Is Required for Its Functional Roles in Histone Acetylation and Cell Proliferation.","date":"2016","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/27402865","citation_count":15,"is_preprint":false},{"pmid":"18059173","id":"PMC_18059173","title":"hADA2a and hADA3 are required for acetylation, transcriptional activity and proliferative effects of beta-catenin.","date":"2007","source":"Cancer biology & therapy","url":"https://pubmed.ncbi.nlm.nih.gov/18059173","citation_count":14,"is_preprint":false},{"pmid":"24464226","id":"PMC_24464226","title":"A functional genomics screen identifies PCAF and ADA3 as regulators of human granzyme B-mediated apoptosis and Bid cleavage.","date":"2014","source":"Cell death and differentiation","url":"https://pubmed.ncbi.nlm.nih.gov/24464226","citation_count":12,"is_preprint":false},{"pmid":"26429915","id":"PMC_26429915","title":"Alteration/Deficiency in Activation 3 (ADA3) Protein, a Cell Cycle Regulator, Associates with the Centromere through CENP-B and Regulates Chromosome Segregation.","date":"2015","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/26429915","citation_count":12,"is_preprint":false},{"pmid":"27852327","id":"PMC_27852327","title":"ADA3 regulates normal and tumor mammary epithelial cell proliferation through c-MYC.","date":"2016","source":"Breast cancer research : BCR","url":"https://pubmed.ncbi.nlm.nih.gov/27852327","citation_count":11,"is_preprint":false},{"pmid":"12034840","id":"PMC_12034840","title":"ADA3-containing complexes associate with estrogen receptor alpha.","date":"2002","source":"Nucleic acids 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spectrum","url":"https://pubmed.ncbi.nlm.nih.gov/37052485","citation_count":4,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":19431,"output_tokens":6036,"usd":0.074416},"stage2":{"model":"claude-opus-4-6","input_tokens":9701,"output_tokens":4813,"usd":0.253245},"total_usd":0.327661,"stage1_batch_id":"msgbatch_01RPbVc9PDH9zQmYK5Hs6srm","stage2_batch_id":"msgbatch_01JVbVLzeKN2yVrsGp3zC8aM","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1993,\n      \"finding\": \"ADA3 (NGG1) was identified as a gene whose mutation prevents GAL4-VP16 toxicity and reduces transactivation by VP16 and GCN4 acidic activation domains; double disruption of ada2 and ada3 shows no additive growth defect, placing them in the same pathway.\",\n      \"method\": \"Genetic screen, gene disruption, epistasis analysis (double mutant), in vitro transcription initiation assay\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with defined phenotypic readout, replicated in multiple mutant backgrounds\",\n      \"pmids\": [\"8413201\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"Ada2, Ada3, and Gcn5 form a heterotrimeric complex in vitro, with Ada2 as the linchpin holding Ada3 and Gcn5 together; Ada3 has two separable domains, with the C-terminal domain sufficient for complex formation and the N-terminal domain proposed to mediate interaction with activation domains.\",\n      \"method\": \"In vitro pulldown/reconstitution, deletion analysis, in vivo LexA fusion activation assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — reconstitution in vitro plus in vivo functional assays with domain dissection\",\n      \"pmids\": [\"7862114\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"NGG1p/ADA3p and ADA2p are coimmunoprecipitated from yeast whole cell extracts, are present in at least four native complexes of different sizes (>2 MDa, ~900 kDa, ~200 kDa), and the complex associates with TBP; this TBP interaction requires residues 274–307 of NGG1p.\",\n      \"method\": \"Co-immunoprecipitation from yeast extracts, ion-exchange chromatography, gel-filtration chromatography, deletion analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP from native extracts with domain mapping, replicated across multiple chromatographic methods\",\n      \"pmids\": [\"9038164\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Yeast Ada2, Ada3, and Gcn5 form the catalytic core of ADA and SAGA HAT complexes that is necessary and sufficient in vitro for nucleosomal HAT activity and lysine specificity; Ada3 is required for Gcn5-dependent nucleosomal HAT activity and facilitates an expanded lysine specificity, while Ada2 potentiates Gcn5 catalytic activity.\",\n      \"method\": \"In vitro reconstitution of catalytic core, nucleosomal HAT activity assays, yeast extract-based HAT assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with functional HAT assay on nucleosomal substrate\",\n      \"pmids\": [\"11773077\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"hADA3 physically interacts with p53 in human cells; this interaction is enhanced after DNA damage due to phosphorylation events in the p53 N-terminus; hADA3 is required for full transcriptional activity of p53 and p53-mediated apoptosis.\",\n      \"method\": \"Yeast p53 dissociator assay, co-immunoprecipitation from human cells, DNA damage experiments, transcriptional reporter assays, apoptosis assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (yeast assay, Co-IP, functional transcription, apoptosis) in single study\",\n      \"pmids\": [\"11707411\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"hADA3 is a novel interacting partner and target of HPV16 E6 oncoprotein; E6 induces hADA3 degradation; hADA3 functions as a coactivator for p53-mediated transactivation by stabilizing p53; E6 mutants that do not degrade p53 but do interact with hADA3 still abrogate p53-mediated transactivation and G1 arrest after DNA damage.\",\n      \"method\": \"Co-immunoprecipitation, protein degradation assays, transcriptional reporter assays, cell cycle analysis (G1 arrest), use of E6 mutants\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods, mechanistic dissection with E6 mutant panel\",\n      \"pmids\": [\"12138191\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"hADA3 directly binds RXRα in vitro and in vivo, is recruited to native RXR response elements in the p21 promoter (by ChIP), and enhances RXRα-mediated transactivation of retinoid target genes; HPV E6 inhibits this RXR-mediated transactivation by targeting hADA3.\",\n      \"method\": \"GST pulldown (in vitro binding), co-immunoprecipitation, chromatin immunoprecipitation (ChIP), transcriptional reporter assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct binding confirmed in vitro and in vivo, ChIP for endogenous promoter occupancy, functional reporter assays\",\n      \"pmids\": [\"12235159\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"ADA3-containing TFTC complex interacts with ERα in a ligand-independent manner; mouse mADA3 does not directly interact with nuclear receptors despite containing LxxLL NR boxes, indicating other TFTC subunits mediate the receptor interaction.\",\n      \"method\": \"Cloning of mouse ADA3, co-immunoprecipitation, interaction assays with ERα\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP from native complex, direct binding tested, but interaction attributed to other complex subunits\",\n      \"pmids\": [\"12034840\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"hADA3 directly interacts with ERα and ERβ in vitro and in vivo; hADA3 is a component of activator complexes bound to the native ER response element in the pS2 promoter; endogenous hADA3 is required for ER-mediated transactivation and estrogen-induced target gene expression; HPV E6 targeting of hADA3 inhibits ERα-mediated transactivation.\",\n      \"method\": \"GST pulldown, co-immunoprecipitation, ChIP, luciferase reporter assay, RT-PCR for endogenous ER target genes, RNA interference (siRNA knockdown of ADA3)\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct binding in vitro and in vivo, endogenous ChIP, RNAi functional validation with multiple orthogonal methods\",\n      \"pmids\": [\"15496419\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Endogenous hAda3 stabilizes p53 protein by promoting its acetylation at p300/CBP acetylation sites; hAda3 is required for DNA damage-induced p53 acetylation, stabilization, and target gene induction; acetylation-defective p53 mutants fail to show hAda3-dependent stabilization.\",\n      \"method\": \"Inducible overexpression and shRNA knockdown of hAda3, western blot for p53 acetylation, p53 mutant analysis, target gene expression assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple genetic approaches (OE, shRNA, acetylation site mutant), mechanistically defined pathway\",\n      \"pmids\": [\"17272277\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"hAda3 is required for p14ARF-induced p53 acetylation and cellular senescence; the N-terminal domain of hAda3 binds p53 but not p300, and its expression blocks p14ARF-induced p53 acetylation and senescence; hAda3 promotes p300-mediated p53 acetylation and siRNA knockdown of hAda3 inhibits endogenous p53 acetylation and p21 accumulation.\",\n      \"method\": \"Dominant-negative N-terminal domain expression, siRNA knockdown, p300-mediated acetylation assay, senescence assay, western blot\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — domain dissection, siRNA functional validation, mechanistic link to p300-mediated acetylation\",\n      \"pmids\": [\"17452980\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Ada3, ERα, and three distinct HATs (p300, PCAF, and Gcn5) co-sediment in a complex (glycerol gradient) and co-immunoprecipitate; Ada3 is required for ligand-dependent recruitment of p300, PCAF, and Gcn5 to the ER-responsive pS2 promoter; Ada3 is critical for estrogen-dependent proliferation of ER-positive breast cancer cells.\",\n      \"method\": \"Glycerol gradient cosedimentation, co-immunoprecipitation, ChIP, shRNA knockdown, 2D and 3D cell proliferation assays\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — complex formation confirmed by two methods, ChIP for promoter recruitment, shRNA functional validation\",\n      \"pmids\": [\"18089809\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Drosophila dADA3 localizes to chromosomes and is significantly reduced in dGcn5 and dAda2a mutant backgrounds; dAda3 loss reduces acetylation at H3K9, H3K14, H4K12, and phosphorylation at H3S10; dAda3 is required for oogenesis and somatic cell viability.\",\n      \"method\": \"Immunofluorescence (localization), genetic mutant analysis, western blot for histone modifications, position effect variegation assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct localization on chromosomes, genetic epistasis with other SAGA subunits, specific histone mark analysis\",\n      \"pmids\": [\"17967867\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"hADA2a and hADA3 physically interact with beta-catenin through Armadillo repeats 6–12 and the C-terminal transactivation domain; both reside with beta-catenin at the c-Myc enhancer; RNAi-mediated reduction of hADA2a and hADA3 results in reduced beta-catenin acetylation, reduced reporter activity, and reduced Wnt target gene activation and proliferation.\",\n      \"method\": \"Co-immunoprecipitation, domain deletion analysis, ChIP, siRNA knockdown, luciferase reporter assay, RT-PCR for endogenous target genes\",\n      \"journal\": \"Cancer biology & therapy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct interaction with domain mapping, ChIP, and functional siRNA knockdown\",\n      \"pmids\": [\"18059173\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"ANCO-1 and ANCO-2 interact with hADA3; the interaction occurs between the conserved C-terminal domain of ANCO-1 and the N-terminal transactivation domain of ADA3; ANCO-1 co-localizes with ADA3, ADA2α/β, and PCAF at nuclear dots; ANCO-1/2 repress ADA3-mediated transcriptional co-activation on nuclear receptors.\",\n      \"method\": \"Co-immunoprecipitation, domain deletion analysis, immunofluorescence co-localization, transcriptional reporter assay\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP with domain mapping and co-localization, functional reporter assay, but single lab study\",\n      \"pmids\": [\"18377363\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Human ADA3 interacts directly with RARα in a hormone-dependent manner through LxxLL motifs in hADA3 and the coactivator pocket of RARα; loss- and gain-of-function mutations in LxxLL motifs alter this interaction; hADA3 associates with RARα target gene promoters in a hormone-dependent manner; ADA3 knockdown impairs RARβ2 expression.\",\n      \"method\": \"Co-immunoprecipitation, LxxLL motif mutagenesis (loss/gain of function), ChIP, RT-PCR for endogenous target genes, structural modeling\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct binding with mutagenesis, ChIP on endogenous promoter, functional gene expression readout\",\n      \"pmids\": [\"20413580\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Germline deletion of Ada3 in mouse causes embryonic lethality; conditional deletion in MEFs causes severe proliferation defect rescued by human Ada3; Ada3 deletion causes G1-to-S delay due to accumulation of CDK inhibitor p27 as an indirect consequence of reduced c-Myc transcription; Ada3 loss causes global histone acetylation changes, abnormal nuclei, mitotic defects, and delayed G2/M-to-G1 transition.\",\n      \"method\": \"Germline knockout (Ada3 null mouse), adenovirus-Cre conditional deletion in MEFs, cell cycle analysis (FACS), ectopic rescue with human Ada3, siRNA knockdown of p27, microarray gene expression analysis, immunofluorescence\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined phenotypic readout, rescue experiment, epistasis with p27 knockdown\",\n      \"pmids\": [\"22736770\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Ada3 deletion leads to enhanced chromosomal aberrations (breaks, fragments, deletions, translocations) and delayed clearance of DNA damage foci (pATM, γH2AX, p53BP1, pRAD51) after ionizing radiation, demonstrating a role in DNA damage response and genomic stability maintenance.\",\n      \"method\": \"Adenovirus-Cre conditional deletion in Ada3fl/fl MEFs, immunofluorescence for DNA damage foci, chromosomal aberration analysis, comet assay\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean conditional KO, multiple DNA repair markers, cytogenetics\",\n      \"pmids\": [\"23095635\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"hADA3 interacts with AATF (apoptosis-antagonizing transcription factor), PPP1R7 (PP1 regulatory subunit 7), and PPP2R5D (PP2A regulatory subunit δ) as novel binding partners; interaction with these partners does not require the C-terminal ADA2-interacting domain of hADA3; expression of these interacting proteins alters hADA3-regulated reporter gene activity.\",\n      \"method\": \"Yeast two-hybrid screen of human cDNA library, co-immunoprecipitation, immunofluorescence co-localization, truncation analysis, reporter gene assay\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — yeast two-hybrid plus Co-IP validation, functional reporter assay, but single lab study\",\n      \"pmids\": [\"23167988\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"PCAF and ADA3 regulate granzyme B-mediated apoptosis upstream of mitochondrial permeabilization; PCAF or ADA3 knockdown reduces Bid cleavage and PACS2 expression; PACS2 knockdown phenocopies PCAF/ADA3 knockdown, defining a PCAF/ADA3→PACS2→Bid pathway for mitochondrial apoptosis.\",\n      \"method\": \"shRNAmiR functional genomic screen, siRNA knockdown validation, cytochrome c release assay, Bid cleavage assay, PACS2 expression analysis\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — unbiased screen followed by independent siRNA validation, genetic epistasis via PACS2 knockdown phenocopy\",\n      \"pmids\": [\"24464226\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"HPV16 E6 targets hADA3 for ubiquitin-mediated degradation via E6AP ubiquitin ligase; hADA3 undergoes SUMOylation that is accelerated by HPV16 E6 and makes hADA3 unstable; Ubc9 depletion prevents rapid E6-mediated hADA3 degradation, revealing a SUMOylation-ubiquitination coupling mechanism.\",\n      \"method\": \"Ubiquitination assay, SUMOylation assay, siRNA knockdown of E6AP and Ubc9, western blot, protein stability assays\",\n      \"journal\": \"Carcinogenesis\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — mechanistically defined PTM pathway with genetic perturbation of individual enzymes\",\n      \"pmids\": [\"24795430\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"ADA3 associates with the α-satellite repeat region of human X chromosome centromeres; ADA3 physically associates with CENP-B through its N-terminus (confirmed by proximity ligation assay and immunofluorescence); an ADA3 mutant unable to bind CENP-B fails to rescue cell proliferation; ADA3 is required for loading CENP-B onto centromeres; Ada3 deletion causes chromosome segregation defects.\",\n      \"method\": \"Proximity ligation assay, immunofluorescence, ChIP on centromeric sequences, deletion analysis, CENP-B binding-deficient mutant rescue assay, cytogenetic analysis of chromosome segregation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal localization and interaction methods, functional mutant rescue, phenotypic validation\",\n      \"pmids\": [\"26429915\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"ADA3 acetylation is dynamically regulated in a cell cycle-dependent manner by HATs GCN5, PCAF, and p300, and is reversed by SIRT1; mass spectrometry and site-directed mutagenesis identified major acetylation sites; acetylation-defective ADA3 mutants associate with HATs and HAT complex components but fail to restore global or locus-specific histone acetylation marks or cell proliferation in Ada3-deleted MEFs.\",\n      \"method\": \"Mass spectrometry to identify acetylation sites, site-directed mutagenesis, inducible expression in Ada3-deleted MEFs, rescue assay, HAT activity assays, co-immunoprecipitation\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — mass spectrometry identification, mutagenesis functional validation, rescue in KO cells\",\n      \"pmids\": [\"27402865\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"EGFR/HER2 signaling through AKT promotes phosphorylation of p300, which in turn promotes ADA3 acetylation; inhibition of HER1/HER2 by lapatinib reduces phospho-AKT, p300 phosphorylation, and ADA3 protein levels; ADA3 acetylation competes with ubiquitination on shared lysine residues to regulate ADA3 stability; ADA3 knockdown mimics lapatinib-induced cell cycle inhibition and apoptosis.\",\n      \"method\": \"RTK inhibitor (lapatinib) treatment, AKT inhibition, p300/PCAF inhibitor (garcinol), acetylation-defective ADA3 mutants (K→R), protein stability (half-life) assays, cell cycle analysis\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — pharmacological and genetic perturbation of each signaling node, mechanistic competition between acetylation and ubiquitination defined by mutant analysis\",\n      \"pmids\": [\"28759294\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TADA3 (ADA3/NGG1) is an essential scaffolding subunit of the Ada2/Ada3/Gcn5 catalytic HAT module within SAGA and related megadalton coactivator complexes, where it facilitates nucleosomal histone acetylation (H3K9/K14, H4K12) by Gcn5 and expanded lysine specificity; it directly interacts with transcription factors including p53, ERα, RXRα, RARα, and β-catenin to recruit HATs (p300, PCAF, Gcn5) to target promoters, stabilizes p53 through promoting its p300-mediated acetylation after DNA damage, associates with centromere protein CENP-B to support proper chromosome segregation, and is itself regulated by dynamic acetylation (by GCN5/PCAF/p300, reversed by SIRT1) downstream of EGFR-AKT-p300 signaling, with HPV16 E6 targeting hADA3 for SUMOylation-coupled ubiquitin/E6AP-mediated degradation to perturb multiple tumor suppressor pathways.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"TADA3 (ADA3/NGG1) is an essential scaffolding subunit of the Ada2/Ada3/Gcn5 histone acetyltransferase (HAT) catalytic module within SAGA-type coactivator complexes, where it enables Gcn5-dependent nucleosomal histone acetylation at H3K9, H3K14, and H4K12 and expands Gcn5 lysine specificity [PMID:11773077, PMID:17967867]. Beyond its core HAT-enabling role, TADA3 functions as a transcriptional coactivator adaptor that directly recruits HATs (p300, PCAF, Gcn5) to promoters occupied by transcription factors including p53, ERα, RARα, RXRα, and β-catenin, thereby coupling activator-dependent gene expression programs to chromatin acetylation [PMID:15496419, PMID:18089809, PMID:20413580, PMID:18059173]. TADA3 stabilizes p53 by promoting its p300-mediated acetylation following DNA damage, is required for DNA damage response fidelity and chromosome segregation through interaction with centromeric CENP-B, and its own stability is regulated by acetylation–ubiquitination competition on shared lysine residues downstream of EGFR–AKT–p300 signaling [PMID:17272277, PMID:23095635, PMID:26429915, PMID:28759294]. HPV16 E6 oncoprotein subverts multiple TADA3-dependent tumor-suppressive pathways by targeting TADA3 for SUMOylation-coupled E6AP-mediated ubiquitin-proteasomal degradation [PMID:24795430, PMID:12138191].\",\n  \"teleology\": [\n    {\n      \"year\": 1993,\n      \"claim\": \"Establishing that ADA3 functions in the same transcriptional coactivation pathway as ADA2 resolved a key question about whether multiple ADA genes act in parallel or sequential steps, placing ADA3 as a core component of an adaptor complex linking acidic activation domains to the transcription machinery.\",\n      \"evidence\": \"Genetic screen for GAL4-VP16 toxicity suppressors and double-mutant epistasis analysis in yeast\",\n      \"pmids\": [\"8413201\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Biochemical nature of the ADA2–ADA3 interaction not yet defined\", \"No enzymatic activity assigned to ADA3\"]\n    },\n    {\n      \"year\": 1995,\n      \"claim\": \"Reconstituting the Ada2/Ada3/Gcn5 heterotrimer in vitro and mapping Ada3 domain architecture answered how these three proteins physically assemble, revealing Ada2 as the linchpin and identifying separable N- and C-terminal functional domains in Ada3.\",\n      \"evidence\": \"In vitro pulldown/reconstitution with recombinant proteins, deletion analysis, LexA fusion activation assays in yeast\",\n      \"pmids\": [\"7862114\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the heterotrimer is sufficient for HAT activity was unknown\", \"Identity of in vivo native complexes containing Ada3 not resolved\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Demonstrating that Ada3/Ada2 reside in multiple native complexes of distinct sizes (>2 MDa, ~900 kDa, ~200 kDa) and interact with TBP established that Ada3 functions within megadalton coactivator assemblies that directly contact basal transcription machinery.\",\n      \"evidence\": \"Co-immunoprecipitation from yeast extracts, gel-filtration and ion-exchange chromatography, domain deletion mapping of TBP interaction\",\n      \"pmids\": [\"9038164\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Composition of the distinct complexes not fully defined\", \"Functional distinction between the different-sized complexes unclear\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Reconstituting the Ada2/Ada3/Gcn5 trimeric core as necessary and sufficient for nucleosomal HAT activity definitively established Ada3 as an essential enabler of Gcn5-mediated chromatin acetylation with expanded lysine specificity, answering why Ada3 loss abolishes histone acetylation in vivo.\",\n      \"evidence\": \"In vitro reconstitution of catalytic core, nucleosomal HAT assays with recombinant and native complexes\",\n      \"pmids\": [\"11773077\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of how Ada3 alters Gcn5 substrate specificity unknown\", \"Whether mammalian ADA3 functions identically in HAT module not tested\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Identifying hADA3 as a physical interactor and functional coactivator of p53 that is enhanced by DNA damage-induced phosphorylation revealed the first direct link between the SAGA adaptor module and a mammalian tumor suppressor.\",\n      \"evidence\": \"Yeast p53 dissociator assay, co-immunoprecipitation from human cells, DNA damage experiments, transcriptional reporters, apoptosis assays\",\n      \"pmids\": [\"11707411\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which hADA3 promotes p53 transcriptional output not defined\", \"Whether HAT activity is required for p53 coactivation unknown\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Showing that HPV16 E6 targets hADA3 for degradation and that E6 mutants unable to degrade p53 but able to target hADA3 still abrogate p53 function established hADA3 as an independent viral target whose loss is sufficient to disable p53-mediated tumor suppression.\",\n      \"evidence\": \"Co-immunoprecipitation, protein degradation assays, E6 mutant panel, cell cycle analysis\",\n      \"pmids\": [\"12138191\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Degradation pathway (ubiquitin ligase identity, PTM requirements) not defined\", \"Whether E6 targets hADA3 in patient-derived HPV-positive cells not shown\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Demonstrating that hADA3 directly binds RXRα and is recruited to retinoid response elements expanded the coactivator function of TADA3 beyond p53 to nuclear receptors, establishing it as a general transcription factor adaptor.\",\n      \"evidence\": \"GST pulldown, co-immunoprecipitation, ChIP on p21 promoter, transcriptional reporter assays\",\n      \"pmids\": [\"12235159\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether hADA3 directly contacts RXRα or does so through an intermediary in the full complex was debated (cf. PMID:12034840)\", \"Structural basis of receptor recognition unknown\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Confirming direct hADA3–ERα/ERβ interaction and showing that endogenous hADA3 is required for estrogen-dependent target gene expression resolved the question of whether hADA3 serves as a bona fide nuclear receptor coactivator for estrogen signaling.\",\n      \"evidence\": \"GST pulldown, co-immunoprecipitation, ChIP on pS2 promoter, siRNA knockdown, RT-PCR for endogenous targets\",\n      \"pmids\": [\"15496419\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether hADA3 interaction with ERα is direct in the context of intact SAGA/ATAC not clarified\", \"Contribution to ER-driven oncogenesis not tested in vivo\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Mechanistically linking hADA3 to p53 stabilization through p300-mediated acetylation and ARF-induced senescence resolved how hADA3 promotes p53 function: by serving as a scaffold that facilitates p300-dependent p53 acetylation, which prevents p53 degradation.\",\n      \"evidence\": \"Overexpression and shRNA knockdown of hAda3, p53 acetylation site mutants, p14ARF-induced senescence assays, dominant-negative N-terminal domain\",\n      \"pmids\": [\"17272277\", \"17452980\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether hADA3 directly bridges p53 and p300 or acts through additional intermediaries not distinguished\", \"In vivo tumor suppressor role not validated\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Showing that Ada3 co-sediments with ERα and three distinct HATs (p300, PCAF, Gcn5) and is required for their ligand-dependent promoter recruitment established Ada3 as the central hub coordinating multiple HATs at hormone-responsive genes.\",\n      \"evidence\": \"Glycerol gradient cosedimentation, co-immunoprecipitation, ChIP, shRNA knockdown, proliferation assays in ER-positive breast cancer cells\",\n      \"pmids\": [\"18089809\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry of the multi-HAT complex undefined\", \"Whether Ada3 bridges HATs simultaneously or sequentially unclear\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Drosophila genetic analysis showed that dADA3 localizes to chromosomes, depends on dGcn5/dAda2a for stability, and is required for H3K9/K14 and H4K12 acetylation, confirming evolutionary conservation of Ada3's HAT-enabling function from yeast to metazoans.\",\n      \"evidence\": \"Immunofluorescence on polytene chromosomes, genetic mutant analysis, western blot for histone marks in Drosophila\",\n      \"pmids\": [\"17967867\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Drosophila Ada3 also serves as a transcription factor adaptor not tested\", \"Target gene specificity not addressed\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Discovering that hADA3 interacts with β-catenin at the c-Myc enhancer and is required for Wnt target gene activation extended TADA3 function to the Wnt signaling pathway, beyond nuclear receptor and p53 programs.\",\n      \"evidence\": \"Co-immunoprecipitation with domain mapping, ChIP at c-Myc enhancer, siRNA knockdown, RT-PCR for Wnt targets\",\n      \"pmids\": [\"18059173\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether β-catenin acetylation by TADA3-associated HATs has functional consequences in vivo unclear\", \"Specificity versus other TCF/LEF coactivators not assessed\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identifying LxxLL motifs in hADA3 as mediating hormone-dependent direct interaction with the RARα coactivator pocket answered how TADA3 physically recognizes nuclear receptors and established a general structural mechanism for its adaptor function.\",\n      \"evidence\": \"LxxLL motif mutagenesis (loss and gain of function), co-immunoprecipitation, ChIP on RARβ2 promoter, endogenous target gene expression\",\n      \"pmids\": [\"20413580\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Crystal structure of ADA3 LxxLL–receptor interface not solved\", \"Whether different LxxLL motifs specify different receptor interactions not fully resolved\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Mouse knockout studies established that Ada3 is essential for embryonic development and cell proliferation, with deletion causing G1/S delay via p27 accumulation (due to reduced c-Myc), global histone acetylation loss, mitotic defects, chromosomal aberrations, and impaired DNA damage repair, consolidating Ada3 as essential for genome integrity.\",\n      \"evidence\": \"Germline Ada3 knockout, conditional deletion in MEFs, FACS cell cycle analysis, human Ada3 rescue, cytogenetics, DNA damage foci kinetics\",\n      \"pmids\": [\"22736770\", \"23095635\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue-specific roles in adult mouse not explored\", \"Whether DNA repair defect is direct or secondary to chromatin acetylation loss unclear\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defining the SUMOylation–ubiquitination coupling mechanism for HPV16 E6-mediated hADA3 degradation via E6AP resolved a longstanding question about the degradation pathway and revealed that SUMOylation primes hADA3 for ubiquitin-dependent destruction.\",\n      \"evidence\": \"Ubiquitination and SUMOylation assays, siRNA knockdown of E6AP and Ubc9, protein stability assays\",\n      \"pmids\": [\"24795430\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"SUMO acceptor lysine sites on hADA3 not mapped\", \"Whether this mechanism operates for other E6 targets unknown\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Identifying a PCAF/ADA3→PACS2→Bid pathway for granzyme B-induced mitochondrial apoptosis revealed a non-transcriptional role for the PCAF/ADA3 module in immune cell-mediated killing.\",\n      \"evidence\": \"shRNAmiR functional genomic screen, independent siRNA validation, cytochrome c release and Bid cleavage assays, PACS2 epistasis\",\n      \"pmids\": [\"24464226\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether ADA3's role in this pathway requires its HAT-scaffolding function not tested\", \"In vivo relevance to anti-tumor immunity not established\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Discovering that ADA3 physically associates with CENP-B at centromeres and is required for CENP-B loading and proper chromosome segregation revealed an unexpected centromeric function beyond transcriptional coactivation.\",\n      \"evidence\": \"Proximity ligation assay, immunofluorescence, ChIP on α-satellite sequences, CENP-B binding-deficient ADA3 mutant rescue, cytogenetics\",\n      \"pmids\": [\"26429915\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether centromeric function involves local histone acetylation not determined\", \"Structural basis of ADA3–CENP-B interaction not solved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Demonstrating that ADA3 itself is dynamically acetylated by GCN5/PCAF/p300 and deacetylated by SIRT1, and that acetylation-defective ADA3 mutants fail to restore histone acetylation or proliferation, established that ADA3 acetylation is a regulatory switch controlling its HAT complex function.\",\n      \"evidence\": \"Mass spectrometry for acetylation sites, site-directed mutagenesis, functional rescue in Ada3-deleted MEFs, co-immunoprecipitation\",\n      \"pmids\": [\"27402865\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How acetylation mechanistically alters ADA3 function (conformational change, binding affinity) undefined\", \"Cell cycle-dependent regulation mechanism not elucidated\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Placing ADA3 acetylation downstream of EGFR–AKT–p300 signaling and showing that acetylation competes with ubiquitination on shared lysine residues to control ADA3 stability connected growth factor signaling to chromatin acetylation through a post-translational switch on ADA3.\",\n      \"evidence\": \"RTK inhibitor (lapatinib) and AKT inhibitor treatment, acetylation-defective K→R mutants, protein half-life assays, cell cycle analysis\",\n      \"pmids\": [\"28759294\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the E3 ubiquitin ligase targeting ADA3 under normal (non-HPV) conditions unknown\", \"In vivo validation of EGFR–ADA3 axis in tumors lacking\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the structural basis by which ADA3 enables Gcn5 nucleosomal substrate recognition and expanded lysine specificity, whether ADA3's centromeric and DNA damage repair functions are mechanistically separable from its HAT-scaffolding role, and identification of the physiological E3 ligase controlling ADA3 turnover in the absence of viral oncoproteins.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No high-resolution structure of ADA3 in the HAT module context\", \"Centromeric versus transcriptional functions not genetically separated\", \"Physiological E3 ubiquitin ligase for ADA3 unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 4, 6, 8, 11, 15]},\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [3, 12, 22]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 4, 8, 13, 15]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [12, 14, 21]},\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [12, 21]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [3, 12, 16, 22]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 4, 8, 11, 13, 15]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [16, 21]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [17]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [4, 19]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [13, 23]}\n    ],\n    \"complexes\": [\n      \"SAGA complex\",\n      \"ADA complex\",\n      \"TFTC/STAGA complex\",\n      \"Ada2/Ada3/Gcn5 HAT module\"\n    ],\n    \"partners\": [\n      \"GCN5\",\n      \"TADA2A\",\n      \"TADA2B\",\n      \"TP53\",\n      \"EP300\",\n      \"PCAF\",\n      \"CENPB\",\n      \"CTNNB1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}