{"gene":"ZZZ3","run_date":"2026-06-11T09:02:07","timeline":{"discoveries":[{"year":2006,"finding":"ZZZ3 (Atac1) is a stable subunit of the ATAC (Ada-two-A-containing) histone acetyltransferase complex in Drosophila, which contains dAda2A, dGcn5, dAda3, dHCF, and Atac1. Atac1 co-purifies with dGcn5 and dAda2A but not with dSAGA-specific components (dAda2B, dSpt3), establishing ATAC as a distinct HAT complex from SAGA.","method":"Affinity purification, mass spectrometry, co-immunoprecipitation, biochemical fractionation","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP and biochemical fractionation, independently followed up in multiple subsequent studies","pmids":["16428443"],"is_preprint":false},{"year":2008,"finding":"The Drosophila ATAC complex (containing Atac1/ZZZ3 ortholog) stimulates nucleosome sliding by ISWI, SWI-SNF, and RSC remodeling complexes but does not itself possess nucleosome-remodeling activity. The complex contains a second HAT subunit (Atac2/KAT14) with preference for H4K16 acetylation.","method":"MudPIT mass spectrometry, in vitro HAT assay, nucleosome-sliding assay, in vivo mutagenesis in D. melanogaster embryos","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution assays combined with in vivo mutagenesis and mass spectrometry in a single rigorous study","pmids":["18327268"],"is_preprint":false},{"year":2018,"finding":"The ZZ-type zinc finger (ZZ domain) of ZZZ3 is a histone H3 reader that specifically recognizes the N-terminal Alanine 1 of histone H3 via caging in an acidic cavity. Depletion of ZZZ3 or disruption of the ZZ–H3 interaction reduces ATAC-dependent H3K9 acetylation at promoters and decreases target gene expression.","method":"Solution NMR structure of ZZ domain in complex with H3 peptide, ZZZ3 knockdown, chromatin immunoprecipitation (ChIP) for H3K9ac, gene expression analysis","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — NMR structure with functional validation by mutagenesis and KD experiments, multiple orthogonal methods in one study","pmids":["30217978"],"is_preprint":false},{"year":2021,"finding":"ZZZ3 and YEATS2, as components of the ATAC histone acetyltransferase complex, are key interactors of the TAZ-CAMTA1 and YAP-TFE3 oncogenic fusion proteins in epithelioid hemangioendothelioma. The fusion proteins recruit the ATAC complex to hyperactivate a TEAD-based transcriptional program and modulate the chromatin environment.","method":"Combined proteomic/genetic screen (Co-IP/MS), integrative next-generation sequencing (ChIP-seq, RNA-seq) in human and murine cell lines","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — proteomic screen confirmed by ChIP-seq and RNA-seq, multiple orthogonal methods across human and murine cell lines","pmids":["33913810"],"is_preprint":false},{"year":2023,"finding":"ATAC complex subunits (including ZZZ3) cannot be detected in the cytoplasm of mammalian cells; the endogenous ATAC complex assembles exclusively in the nucleus. Core modules of ATAC assemble co-translationally in the cytoplasm, but unlike SAGA, assembled ATAC complex is nuclear-restricted.","method":"Subcellular fractionation, co-translational assembly assays, endogenous tagging, immunofluorescence in mammalian cells","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — direct fractionation and co-translational assembly assays with endogenous tagging, multiple orthogonal approaches in single study","pmids":["37682711"],"is_preprint":false},{"year":2024,"finding":"Knockdown of ZZZ3 in human embryonic stem cells negatively impacts ribosome biogenesis, translation, and mTOR signaling, leading to a significant reduction in cell proliferation without affecting pluripotency, suggesting ZZZ3-depleted ESCs enter a 'dormant-like' state.","method":"siRNA knockdown of ZZZ3 in human ESCs, ribosome biogenesis assays, translation assays, mTOR signaling readouts, proliferation assays, pluripotency marker analysis","journal":"Stem cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — loss-of-function with multiple cellular phenotype readouts but single lab, no pathway reconstitution or epistasis","pmids":["38701777"],"is_preprint":false},{"year":2025,"finding":"O-GlcNAcylation of YEATS2 (a subunit of the ATAC complex) promotes the chromatin association of YEATS2 and its affinity with other ATAC components including ZZZ3, GCN5, and PCAF, thereby stabilizing the ATAC complex on chromatin and supporting H3K9 acetylation.","method":"Electron transfer dissociation mass spectrometry (site mapping), Co-IP, ChIP assay, site-directed mutagenesis (T604A), xenograft experiments","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP and ChIP with mutagenesis in single lab; ZZZ3 involvement shown as ATAC complex partner, not directly modified","pmids":["40541806"],"is_preprint":false},{"year":2024,"finding":"ZZZ3 upregulates the transcription of CD70 in diffuse large B-cell lymphoma (DLBCL) cells by binding to the CD70 super-enhancer. ZZZ3 overexpression counteracted the effects of CD70 silencing on NK cell proliferation and cytotoxicity, placing ZZZ3 upstream of CD70 in the regulation of DLBCL-NK cell interactions.","method":"H3K27ac ChIP-seq, single-cell RNA-seq, siRNA silencing, MTS proliferation assay, LDH release assay, ZZZ3 overexpression","journal":"Experimental biology and medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — ChIP-seq and functional assays in single lab, but limited mechanistic detail on direct ZZZ3-SE binding","pmids":["39376717"],"is_preprint":false}],"current_model":"ZZZ3 (ATAC1) is a dedicated nuclear subunit of the ATAC (Ada-Two-A-Containing) histone acetyltransferase complex; its ZZ-type zinc finger domain acts as a direct histone H3 reader (binding the H3 N-terminal Ala1 in an acidic cavity as determined by NMR), thereby recruiting the ATAC complex to chromatin to maintain H3K9 acetylation and target gene activation, while its nuclear-restricted localization is established by co-translational cytoplasmic assembly followed by exclusive nuclear residence of the intact complex."},"narrative":{"mechanistic_narrative":"ZZZ3 is a dedicated nuclear subunit of the ATAC (Ada-Two-A-Containing) histone acetyltransferase complex, where it functions as a chromatin reader that directs the complex's acetyltransferase activity to target genes [PMID:16428443, PMID:30217978]. First identified in Drosophila as a stable component co-purifying with the catalytic Gcn5 module and the adaptors Ada2A and Ada3 — but not with SAGA-specific subunits — ZZZ3 helped define ATAC as a HAT complex distinct from SAGA [PMID:16428443]; the complex carries two acetyltransferase activities and stimulates nucleosome sliding by ISWI-, SWI-SNF-, and RSC-type remodelers without itself remodeling nucleosomes [PMID:18327268]. Mechanistically, the ZZ-type zinc finger of ZZZ3 reads histone H3 by caging its N-terminal Ala1 in an acidic cavity, and loss of ZZZ3 or disruption of this ZZ–H3 contact reduces ATAC-dependent H3K9 acetylation at promoters and lowers target gene expression [PMID:30217978]. The intact complex is nuclear-restricted: although core modules assemble co-translationally in the cytoplasm, assembled ATAC is detected exclusively in the nucleus [PMID:37682711]. ZZZ3 contributes to disease-relevant transcriptional programs, serving as an interactor recruited by TAZ-CAMTA1 and YAP-TFE3 oncogenic fusions to hyperactivate a TEAD program in epithelioid hemangioendothelioma [PMID:33913810] and binding the CD70 super-enhancer to drive CD70 transcription in diffuse large B-cell lymphoma [PMID:39376717]. In human embryonic stem cells, ZZZ3 supports ribosome biogenesis, translation, mTOR signaling, and proliferation without affecting pluripotency [PMID:38701777].","teleology":[{"year":2006,"claim":"Establishing that ZZZ3 is a bona fide subunit of a HAT complex distinct from SAGA defined its molecular context and the complex it operates within.","evidence":"Affinity purification, mass spectrometry, and reciprocal co-immunoprecipitation/fractionation in Drosophila","pmids":["16428443"],"confidence":"High","gaps":["Did not define ZZZ3's specific molecular function within ATAC","Mammalian ATAC composition not addressed","No domain-level mechanism for ZZZ3"]},{"year":2008,"claim":"Characterizing ATAC's enzymatic and chromatin activities placed ZZZ3 within a complex that both acetylates histones and stimulates ATP-dependent remodelers.","evidence":"MudPIT mass spectrometry, in vitro HAT and nucleosome-sliding assays, and in vivo mutagenesis in Drosophila embryos","pmids":["18327268"],"confidence":"High","gaps":["Did not assign a specific function to the ZZZ3 subunit itself","Mechanism linking acetylation to remodeler stimulation unresolved"]},{"year":2018,"claim":"Solving the ZZ domain structure and its H3 recognition mode revealed how ZZZ3 functions as a histone reader that targets ATAC acetyltransferase activity to chromatin.","evidence":"Solution NMR of the ZZ domain–H3 peptide complex with ZZZ3 knockdown, H3K9ac ChIP, and expression analysis","pmids":["30217978"],"confidence":"High","gaps":["Genome-wide map of ZZZ3-dependent recruitment sites not defined","Whether other ATAC readers cooperate with the ZZ domain unaddressed"]},{"year":2021,"claim":"Identifying ZZZ3/ATAC as an effector recruited by oncogenic fusion proteins connected the reader function to a disease transcriptional program.","evidence":"Co-IP/MS proteomic-genetic screen with ChIP-seq and RNA-seq in human and murine cell lines","pmids":["33913810"],"confidence":"High","gaps":["Direct ZZZ3 contribution versus other ATAC subunits not dissected","Whether the ZZ–H3 reader function is required for fusion recruitment unknown"]},{"year":2023,"claim":"Demonstrating nuclear-exclusive residence of assembled ATAC clarified where ZZZ3 acts and how its localization differs from the related SAGA complex.","evidence":"Subcellular fractionation, co-translational assembly assays, and endogenous tagging with immunofluorescence in mammalian cells","pmids":["37682711"],"confidence":"High","gaps":["Mechanism enforcing nuclear restriction not identified","Whether ZZZ3 specifically governs import unknown"]},{"year":2024,"claim":"Loss-of-function in human ESCs linked ZZZ3 to ribosome biogenesis, translation, and mTOR-dependent proliferation, extending its role beyond chromatin readout.","evidence":"siRNA knockdown in human ESCs with ribosome biogenesis, translation, mTOR, proliferation, and pluripotency readouts","pmids":["38701777"],"confidence":"Medium","gaps":["No pathway reconstitution or epistasis linking ATAC activity to these phenotypes","Single lab, no rescue with ZZ-mutant","Direct transcriptional targets driving the dormant-like state not defined"]},{"year":2024,"claim":"Mapping ZZZ3 to the CD70 super-enhancer in DLBCL implicated it in regulating tumor–NK cell interactions through enhancer-driven transcription.","evidence":"H3K27ac ChIP-seq, scRNA-seq, siRNA silencing, overexpression, and NK proliferation/cytotoxicity assays in DLBCL cells","pmids":["39376717"],"confidence":"Medium","gaps":["Direct ZZZ3–super-enhancer binding not structurally established","Whether ZZ-domain reader activity is required not tested"]},{"year":2025,"claim":"Showing that YEATS2 O-GlcNAcylation stabilizes ATAC on chromatin and strengthens its affinity for ZZZ3 revealed a post-translational input regulating complex assembly on DNA.","evidence":"ETD mass spectrometry site mapping, Co-IP, ChIP, T604A mutagenesis, and xenograft experiments","pmids":["40541806"],"confidence":"Medium","gaps":["ZZZ3 itself not directly modified; effect is via YEATS2","Single lab without orthogonal confirmation","Quantitative contribution of ZZZ3 affinity change to H3K9ac unresolved"]},{"year":null,"claim":"How the ZZ-domain reader function mechanistically couples to ATAC's downstream roles in ribosome biogenesis, mTOR signaling, and disease-specific transcriptional programs remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No reconstitution linking ZZ–H3 recognition to mTOR/translation phenotypes","No structure of the full mammalian ATAC complex bound to chromatin","Mechanism of nuclear restriction unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0042393","term_label":"histone binding","supporting_discovery_ids":[2]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[2,3,7]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[2,7]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[4]},{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[2,4]}],"pathway":[{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[0,2]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[2,3,7]}],"complexes":["ATAC (Ada-Two-A-Containing) HAT complex"],"partners":["GCN5","ADA2A","ADA3","YEATS2","KAT14","PCAF"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8IYH5","full_name":"ZZ-type zinc finger-containing protein 3","aliases":[],"length_aa":903,"mass_kda":102.0,"function":"Histone H3 reader that is required for the ATAC complex-mediated maintenance of histone acetylation and gene activation (PubMed:30217978). Component of the ATAC complex, a complex with histone acetyltransferase activity on histones H3 and H4 (PubMed:19103755)","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q8IYH5/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ZZZ3","classification":"Not Classified","n_dependent_lines":234,"n_total_lines":1208,"dependency_fraction":0.19370860927152317},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"ACTB","stoichiometry":0.2},{"gene":"HIST2H2BE","stoichiometry":0.2},{"gene":"U2AF2","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/ZZZ3","total_profiled":1310},"omim":[{"mim_id":"619892","title":"ZINC FINGER ZZ-TYPE DOMAIN-CONTAINING PROTEIN 3; ZZZ3","url":"https://www.omim.org/entry/619892"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Nucleoplasm","reliability":"Enhanced"},{"location":"Nucleoli","reliability":"Enhanced"},{"location":"Nucleoli rim","reliability":"Enhanced"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/ZZZ3"},"hgnc":{"alias_symbol":["DKFZP564I052","ATAC1"],"prev_symbol":[]},"alphafold":{"accession":"Q8IYH5","domains":[{"cath_id":"-","chopping":"793-889","consensus_level":"medium","plddt":80.0045,"start":793,"end":889},{"cath_id":"1.10.287","chopping":"496-566","consensus_level":"high","plddt":88.6721,"start":496,"end":566},{"cath_id":"1.10.10","chopping":"658-730","consensus_level":"high","plddt":79.1837,"start":658,"end":730}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8IYH5","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8IYH5-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8IYH5-F1-predicted_aligned_error_v6.png","plddt_mean":53.47},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ZZZ3","jax_strain_url":"https://www.jax.org/strain/search?query=ZZZ3"},"sequence":{"accession":"Q8IYH5","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8IYH5.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8IYH5/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8IYH5"}},"corpus_meta":[{"pmid":"18327268","id":"PMC_18327268","title":"ATAC is a double histone acetyltransferase complex that stimulates nucleosome sliding.","date":"2008","source":"Nature structural & molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/18327268","citation_count":155,"is_preprint":false},{"pmid":"16428443","id":"PMC_16428443","title":"Host cell factor and an uncharacterized SANT domain protein are stable components of ATAC, a novel dAda2A/dGcn5-containing histone acetyltransferase complex in Drosophila.","date":"2006","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/16428443","citation_count":100,"is_preprint":false},{"pmid":"30217978","id":"PMC_30217978","title":"The ZZ-type zinc finger of ZZZ3 modulates the ATAC complex-mediated histone acetylation and gene activation.","date":"2018","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/30217978","citation_count":62,"is_preprint":false},{"pmid":"33913810","id":"PMC_33913810","title":"TAZ-CAMTA1 and YAP-TFE3 alter the TAZ/YAP transcriptome by recruiting the ATAC histone acetyltransferase complex.","date":"2021","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/33913810","citation_count":57,"is_preprint":false},{"pmid":"15930127","id":"PMC_15930127","title":"Inhibition of translation initiation by volatile anesthetics involves nutrient-sensitive GCN-independent and -dependent processes in yeast.","date":"2005","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/15930127","citation_count":25,"is_preprint":false},{"pmid":"37682711","id":"PMC_37682711","title":"ATAC and SAGA co-activator complexes utilize co-translational assembly, but their cellular localization properties and functions are distinct.","date":"2023","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/37682711","citation_count":21,"is_preprint":false},{"pmid":"21304275","id":"PMC_21304275","title":"NF-Y affects histone acetylation and H2A.Z deposition in cell cycle promoters.","date":"2011","source":"Epigenetics","url":"https://pubmed.ncbi.nlm.nih.gov/21304275","citation_count":16,"is_preprint":false},{"pmid":"26282996","id":"PMC_26282996","title":"Sequence Kernel Association Analysis of Rare Variant Set Based on the Marginal Regression Model for Binary Traits.","date":"2015","source":"Genetic epidemiology","url":"https://pubmed.ncbi.nlm.nih.gov/26282996","citation_count":13,"is_preprint":false},{"pmid":"38102586","id":"PMC_38102586","title":"Radiotranscriptomics of non-small cell lung carcinoma for assessing high-level clinical outcomes using a machine learning-derived multi-modal signature.","date":"2023","source":"Biomedical engineering online","url":"https://pubmed.ncbi.nlm.nih.gov/38102586","citation_count":11,"is_preprint":false},{"pmid":"39583859","id":"PMC_39583859","title":"Exploring Cuproptosis-Related Genes and Diagnostic Models in Renal Ischemia-Reperfusion Injury Using Bioinformatics, Machine Learning, and Experimental 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Atac1 co-purifies with dGcn5 and dAda2A but not with dSAGA-specific components (dAda2B, dSpt3), establishing ATAC as a distinct HAT complex from SAGA.\",\n      \"method\": \"Affinity purification, mass spectrometry, co-immunoprecipitation, biochemical fractionation\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP and biochemical fractionation, independently followed up in multiple subsequent studies\",\n      \"pmids\": [\"16428443\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"The Drosophila ATAC complex (containing Atac1/ZZZ3 ortholog) stimulates nucleosome sliding by ISWI, SWI-SNF, and RSC remodeling complexes but does not itself possess nucleosome-remodeling activity. The complex contains a second HAT subunit (Atac2/KAT14) with preference for H4K16 acetylation.\",\n      \"method\": \"MudPIT mass spectrometry, in vitro HAT assay, nucleosome-sliding assay, in vivo mutagenesis in D. melanogaster embryos\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution assays combined with in vivo mutagenesis and mass spectrometry in a single rigorous study\",\n      \"pmids\": [\"18327268\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The ZZ-type zinc finger (ZZ domain) of ZZZ3 is a histone H3 reader that specifically recognizes the N-terminal Alanine 1 of histone H3 via caging in an acidic cavity. Depletion of ZZZ3 or disruption of the ZZ–H3 interaction reduces ATAC-dependent H3K9 acetylation at promoters and decreases target gene expression.\",\n      \"method\": \"Solution NMR structure of ZZ domain in complex with H3 peptide, ZZZ3 knockdown, chromatin immunoprecipitation (ChIP) for H3K9ac, gene expression analysis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — NMR structure with functional validation by mutagenesis and KD experiments, multiple orthogonal methods in one study\",\n      \"pmids\": [\"30217978\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"ZZZ3 and YEATS2, as components of the ATAC histone acetyltransferase complex, are key interactors of the TAZ-CAMTA1 and YAP-TFE3 oncogenic fusion proteins in epithelioid hemangioendothelioma. The fusion proteins recruit the ATAC complex to hyperactivate a TEAD-based transcriptional program and modulate the chromatin environment.\",\n      \"method\": \"Combined proteomic/genetic screen (Co-IP/MS), integrative next-generation sequencing (ChIP-seq, RNA-seq) in human and murine cell lines\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — proteomic screen confirmed by ChIP-seq and RNA-seq, multiple orthogonal methods across human and murine cell lines\",\n      \"pmids\": [\"33913810\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ATAC complex subunits (including ZZZ3) cannot be detected in the cytoplasm of mammalian cells; the endogenous ATAC complex assembles exclusively in the nucleus. Core modules of ATAC assemble co-translationally in the cytoplasm, but unlike SAGA, assembled ATAC complex is nuclear-restricted.\",\n      \"method\": \"Subcellular fractionation, co-translational assembly assays, endogenous tagging, immunofluorescence in mammalian cells\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct fractionation and co-translational assembly assays with endogenous tagging, multiple orthogonal approaches in single study\",\n      \"pmids\": [\"37682711\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Knockdown of ZZZ3 in human embryonic stem cells negatively impacts ribosome biogenesis, translation, and mTOR signaling, leading to a significant reduction in cell proliferation without affecting pluripotency, suggesting ZZZ3-depleted ESCs enter a 'dormant-like' state.\",\n      \"method\": \"siRNA knockdown of ZZZ3 in human ESCs, ribosome biogenesis assays, translation assays, mTOR signaling readouts, proliferation assays, pluripotency marker analysis\",\n      \"journal\": \"Stem cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — loss-of-function with multiple cellular phenotype readouts but single lab, no pathway reconstitution or epistasis\",\n      \"pmids\": [\"38701777\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"O-GlcNAcylation of YEATS2 (a subunit of the ATAC complex) promotes the chromatin association of YEATS2 and its affinity with other ATAC components including ZZZ3, GCN5, and PCAF, thereby stabilizing the ATAC complex on chromatin and supporting H3K9 acetylation.\",\n      \"method\": \"Electron transfer dissociation mass spectrometry (site mapping), Co-IP, ChIP assay, site-directed mutagenesis (T604A), xenograft experiments\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP and ChIP with mutagenesis in single lab; ZZZ3 involvement shown as ATAC complex partner, not directly modified\",\n      \"pmids\": [\"40541806\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ZZZ3 upregulates the transcription of CD70 in diffuse large B-cell lymphoma (DLBCL) cells by binding to the CD70 super-enhancer. ZZZ3 overexpression counteracted the effects of CD70 silencing on NK cell proliferation and cytotoxicity, placing ZZZ3 upstream of CD70 in the regulation of DLBCL-NK cell interactions.\",\n      \"method\": \"H3K27ac ChIP-seq, single-cell RNA-seq, siRNA silencing, MTS proliferation assay, LDH release assay, ZZZ3 overexpression\",\n      \"journal\": \"Experimental biology and medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — ChIP-seq and functional assays in single lab, but limited mechanistic detail on direct ZZZ3-SE binding\",\n      \"pmids\": [\"39376717\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ZZZ3 (ATAC1) is a dedicated nuclear subunit of the ATAC (Ada-Two-A-Containing) histone acetyltransferase complex; its ZZ-type zinc finger domain acts as a direct histone H3 reader (binding the H3 N-terminal Ala1 in an acidic cavity as determined by NMR), thereby recruiting the ATAC complex to chromatin to maintain H3K9 acetylation and target gene activation, while its nuclear-restricted localization is established by co-translational cytoplasmic assembly followed by exclusive nuclear residence of the intact complex.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ZZZ3 is a dedicated nuclear subunit of the ATAC (Ada-Two-A-Containing) histone acetyltransferase complex, where it functions as a chromatin reader that directs the complex's acetyltransferase activity to target genes [#0, #2]. First identified in Drosophila as a stable component co-purifying with the catalytic Gcn5 module and the adaptors Ada2A and Ada3 — but not with SAGA-specific subunits — ZZZ3 helped define ATAC as a HAT complex distinct from SAGA [#0]; the complex carries two acetyltransferase activities and stimulates nucleosome sliding by ISWI-, SWI-SNF-, and RSC-type remodelers without itself remodeling nucleosomes [#1]. Mechanistically, the ZZ-type zinc finger of ZZZ3 reads histone H3 by caging its N-terminal Ala1 in an acidic cavity, and loss of ZZZ3 or disruption of this ZZ–H3 contact reduces ATAC-dependent H3K9 acetylation at promoters and lowers target gene expression [#2]. The intact complex is nuclear-restricted: although core modules assemble co-translationally in the cytoplasm, assembled ATAC is detected exclusively in the nucleus [#4]. ZZZ3 contributes to disease-relevant transcriptional programs, serving as an interactor recruited by TAZ-CAMTA1 and YAP-TFE3 oncogenic fusions to hyperactivate a TEAD program in epithelioid hemangioendothelioma [#3] and binding the CD70 super-enhancer to drive CD70 transcription in diffuse large B-cell lymphoma [#7]. In human embryonic stem cells, ZZZ3 supports ribosome biogenesis, translation, mTOR signaling, and proliferation without affecting pluripotency [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Establishing that ZZZ3 is a bona fide subunit of a HAT complex distinct from SAGA defined its molecular context and the complex it operates within.\",\n      \"evidence\": \"Affinity purification, mass spectrometry, and reciprocal co-immunoprecipitation/fractionation in Drosophila\",\n      \"pmids\": [\"16428443\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define ZZZ3's specific molecular function within ATAC\", \"Mammalian ATAC composition not addressed\", \"No domain-level mechanism for ZZZ3\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Characterizing ATAC's enzymatic and chromatin activities placed ZZZ3 within a complex that both acetylates histones and stimulates ATP-dependent remodelers.\",\n      \"evidence\": \"MudPIT mass spectrometry, in vitro HAT and nucleosome-sliding assays, and in vivo mutagenesis in Drosophila embryos\",\n      \"pmids\": [\"18327268\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not assign a specific function to the ZZZ3 subunit itself\", \"Mechanism linking acetylation to remodeler stimulation unresolved\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Solving the ZZ domain structure and its H3 recognition mode revealed how ZZZ3 functions as a histone reader that targets ATAC acetyltransferase activity to chromatin.\",\n      \"evidence\": \"Solution NMR of the ZZ domain–H3 peptide complex with ZZZ3 knockdown, H3K9ac ChIP, and expression analysis\",\n      \"pmids\": [\"30217978\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Genome-wide map of ZZZ3-dependent recruitment sites not defined\", \"Whether other ATAC readers cooperate with the ZZ domain unaddressed\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identifying ZZZ3/ATAC as an effector recruited by oncogenic fusion proteins connected the reader function to a disease transcriptional program.\",\n      \"evidence\": \"Co-IP/MS proteomic-genetic screen with ChIP-seq and RNA-seq in human and murine cell lines\",\n      \"pmids\": [\"33913810\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct ZZZ3 contribution versus other ATAC subunits not dissected\", \"Whether the ZZ–H3 reader function is required for fusion recruitment unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Demonstrating nuclear-exclusive residence of assembled ATAC clarified where ZZZ3 acts and how its localization differs from the related SAGA complex.\",\n      \"evidence\": \"Subcellular fractionation, co-translational assembly assays, and endogenous tagging with immunofluorescence in mammalian cells\",\n      \"pmids\": [\"37682711\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism enforcing nuclear restriction not identified\", \"Whether ZZZ3 specifically governs import unknown\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Loss-of-function in human ESCs linked ZZZ3 to ribosome biogenesis, translation, and mTOR-dependent proliferation, extending its role beyond chromatin readout.\",\n      \"evidence\": \"siRNA knockdown in human ESCs with ribosome biogenesis, translation, mTOR, proliferation, and pluripotency readouts\",\n      \"pmids\": [\"38701777\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No pathway reconstitution or epistasis linking ATAC activity to these phenotypes\", \"Single lab, no rescue with ZZ-mutant\", \"Direct transcriptional targets driving the dormant-like state not defined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Mapping ZZZ3 to the CD70 super-enhancer in DLBCL implicated it in regulating tumor–NK cell interactions through enhancer-driven transcription.\",\n      \"evidence\": \"H3K27ac ChIP-seq, scRNA-seq, siRNA silencing, overexpression, and NK proliferation/cytotoxicity assays in DLBCL cells\",\n      \"pmids\": [\"39376717\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct ZZZ3–super-enhancer binding not structurally established\", \"Whether ZZ-domain reader activity is required not tested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Showing that YEATS2 O-GlcNAcylation stabilizes ATAC on chromatin and strengthens its affinity for ZZZ3 revealed a post-translational input regulating complex assembly on DNA.\",\n      \"evidence\": \"ETD mass spectrometry site mapping, Co-IP, ChIP, T604A mutagenesis, and xenograft experiments\",\n      \"pmids\": [\"40541806\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"ZZZ3 itself not directly modified; effect is via YEATS2\", \"Single lab without orthogonal confirmation\", \"Quantitative contribution of ZZZ3 affinity change to H3K9ac unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the ZZ-domain reader function mechanistically couples to ATAC's downstream roles in ribosome biogenesis, mTOR signaling, and disease-specific transcriptional programs remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No reconstitution linking ZZ–H3 recognition to mTOR/translation phenotypes\", \"No structure of the full mammalian ATAC complex bound to chromatin\", \"Mechanism of nuclear restriction unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [2]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [2, 3, 7]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [2, 7]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [2, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [2, 3, 7]}\n    ],\n    \"complexes\": [\"ATAC (Ada-Two-A-Containing) HAT complex\"],\n    \"partners\": [\"GCN5\", \"ADA2A\", \"ADA3\", \"YEATS2\", \"KAT14\", \"PCAF\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}