{"gene":"ANKRD44","run_date":"2026-06-09T22:02:43","timeline":{"discoveries":[{"year":2008,"finding":"ANKRD44 (along with Ankrd28 and Ankrd52) was identified as an ankyrin repeat subunit of the PP6 holoenzyme complex. Tagged Ankrd28 (the closest characterized paralog used as proxy) coprecipitated with PP6 catalytic subunit but not PP2A or PP4, and with SAPS domain subunits PP6R1 and PP6R3. The C-terminal region of PP6R1 was sufficient to coprecipitate the ankyrin subunit but not PP6 itself, establishing PP6R1 as a scaffold with separate binding regions for PP6 and the ankyrin repeat subunit. Endogenous PP6 holoenzymes containing PP6R1, PP6R3, and Ankrd28 eluted at >440 kDa from Superose 12, consistent with a heterotrimer.","method":"FLAG co-immunoprecipitation, mass spectrometry, size-exclusion chromatography (Superose 12), domain-mapping pulldown with C-terminal PP6R1 fragment","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP with MS identification, domain-mapping, gel-filtration sizing, replicated across multiple tagged constructs and endogenous proteins in a single rigorous study","pmids":["18186651"],"is_preprint":false},{"year":2008,"finding":"Knockdown of PP6R1 or Ankrd28 (but not PP6R3) produced equivalent enhancement of IκBε degradation in response to TNFα, placing the PP6–PP6R1–Ankrd28/ANKRD44 complex upstream of IκBε stability in the NF-κB pathway.","method":"siRNA knockdown of individual PP6 complex subunits followed by TNFα stimulation and IκBε degradation assay","journal":"Biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean knockdown with defined pathway readout, single lab, two subunit comparisons providing specificity control","pmids":["18186651"],"is_preprint":false},{"year":2024,"finding":"PP6 functions as a heterotrimer composed of PP6c catalytic subunit, a regulatory subunit (PP6R1–3), and a scaffold subunit (ANKRD28, ANKRD44, or ANKRD52). The PP6c–PP6R3 complex specifically regulates cancer stem cell (CSC) marker expression in colorectal cancer cells, and PP6c knockdown decreased colony-forming ability and in vivo proliferation.","method":"PP6c siRNA knockdown, transcriptome analysis, sphere-formation CSC assay, in vivo proliferation assay in CRC cell lines","journal":"Cancer science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional knockdown with transcriptome readout and in vivo validation, single lab; ANKRD44 named as scaffold subunit by established complex membership but functional experiments focused on PP6c/PP6R3","pmids":["39014521"],"is_preprint":false},{"year":2019,"finding":"Silencing of ANKRD44 in the HER2+ breast cancer cell line BT474 produced partial resistance to trastuzumab, constitutive activation of NF-κB via the TAK1/AKT pathway, increased glycolysis (evidenced by LDHB upregulation), and increased TROP2 expression.","method":"ANKRD44 siRNA silencing in BT474 cells, trastuzumab resistance assay, NF-κB activity measurement, LDHB and TROP2 Western blot, glycolysis assay","journal":"Frontiers in oncology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — loss-of-function with multiple downstream readouts (NF-κB, glycolysis, TROP2), single lab, no rescue experiment or pathway reconstruction in vitro","pmids":["31297336"],"is_preprint":false},{"year":2021,"finding":"miR-133a-3p directly targets the ANKRD44 3′UTR (validated by dual luciferase assay) and negatively regulates ANKRD44 expression. Overexpression of ANKRD44 rescued the anti-osteogenic effects of miR-133a-3p in bone marrow mesenchymal stem cells, placing ANKRD44 downstream of miR-133a-3p in the osteogenic differentiation pathway.","method":"Dual luciferase reporter assay, qRT-PCR, Western blot, miR-133a-3p mimic/inhibitor transfection, ALP staining, alizarin red staining, ANKRD44 overexpression rescue experiment","journal":"General physiology and biophysics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct target validation by luciferase assay plus rescue experiment, single lab, multiple orthogonal readouts of osteogenic differentiation","pmids":["34350837"],"is_preprint":false}],"current_model":"ANKRD44 is an ankyrin repeat scaffold subunit of the PP6 heterotrimer, binding to SAPS-domain regulatory subunits (PP6R1/R3) via a distinct region of PP6R1 to form a >440 kDa complex that is specific to PP6 (not PP2A or PP4) and regulates IκBε stability downstream of TNFα; loss of ANKRD44 also activates NF-κB via TAK1/AKT to promote trastuzumab resistance and increased glycolysis in HER2+ breast cancer cells, and ANKRD44 acts as a direct downstream target of miR-133a-3p to promote osteogenic differentiation of mesenchymal stem cells."},"narrative":{"mechanistic_narrative":"ANKRD44 is an ankyrin-repeat scaffold subunit of the protein phosphatase 6 (PP6) holoenzyme, one of three interchangeable ankyrin subunits (with ANKRD28 and ANKRD52) that assemble with the PP6 catalytic subunit and a SAPS-domain regulatory subunit (PP6R1–R3) into a >440 kDa heterotrimer specific to PP6 rather than PP2A or PP4 [PMID:18186651, PMID:39014521]. Within this complex, PP6R1 serves as the bridging scaffold, using a C-terminal region to recruit the ankyrin subunit through a site distinct from its PP6 catalytic-binding region [PMID:18186651]. Functionally, the PP6–PP6R1–ankyrin complex restrains TNFα-induced degradation of IκBε, positioning ANKRD44 as a negative regulator of NF-κB signaling [PMID:18186651]. Consistent with this role, ANKRD44 loss in HER2+ breast cancer cells drives constitutive NF-κB activation through the TAK1/AKT axis, increased glycolysis, and partial trastuzumab resistance [PMID:31297336]. ANKRD44 is itself a direct target of miR-133a-3p, and its expression promotes osteogenic differentiation of bone marrow mesenchymal stem cells [PMID:34350837].","teleology":[{"year":2008,"claim":"Establishing how the PP6 phosphatase is built, this work defined ANKRD44 as one of a family of ankyrin-repeat subunits that assemble with PP6 catalytic and SAPS-domain regulatory subunits into a specific heterotrimer.","evidence":"FLAG co-immunoprecipitation with mass spectrometry, size-exclusion chromatography, and domain-mapping pulldowns using a C-terminal PP6R1 fragment","pmids":["18186651"],"confidence":"High","gaps":["Most assembly data used ANKRD28 as proxy rather than ANKRD44 directly","No structural model of the heterotrimer or the ankyrin–PP6R1 interface","Functional distinction between the three interchangeable ankyrin subunits not resolved"]},{"year":2008,"claim":"Linking the complex to a signaling output, knockdown placed the PP6–PP6R1–ankyrin assembly upstream of IκBε stability, implicating it as a brake on NF-κB activation.","evidence":"siRNA knockdown of individual PP6 subunits followed by TNFα stimulation and IκBε degradation assay","pmids":["18186651"],"confidence":"Medium","gaps":["Direct substrate of the phosphatase in this pathway not identified","Effect attributed to ANKRD28; ANKRD44-specific contribution not isolated","Single lab"]},{"year":2019,"claim":"Extending the NF-κB link to cancer, ANKRD44 loss was shown to drive trastuzumab resistance via constitutive NF-κB activation and metabolic reprogramming in HER2+ breast cancer cells.","evidence":"ANKRD44 siRNA silencing in BT474 cells with trastuzumab resistance, NF-κB, glycolysis, LDHB and TROP2 readouts","pmids":["31297336"],"confidence":"Medium","gaps":["No rescue experiment to confirm specificity","Connection to PP6 phosphatase activity not mechanistically reconstructed","TAK1/AKT-to-NF-κB causal chain inferred from correlative readouts"]},{"year":2021,"claim":"Identifying an upstream regulator, ANKRD44 was validated as a direct miR-133a-3p target whose expression promotes osteogenic differentiation.","evidence":"Dual luciferase reporter assay, miR mimic/inhibitor transfection, and ANKRD44 overexpression rescue with ALP and alizarin red staining in BMSCs","pmids":["34350837"],"confidence":"Medium","gaps":["Downstream effector mechanism in osteogenesis not defined","Whether PP6 complex assembly mediates the osteogenic effect untested","Single lab"]},{"year":2024,"claim":"Reaffirming complex architecture in a new context, the three-subunit PP6 composition was restated while CSC-regulatory function was attributed to the PP6c–PP6R3 pairing.","evidence":"PP6c siRNA knockdown, transcriptome analysis, sphere-formation and in vivo proliferation assays in colorectal cancer cells","pmids":["39014521"],"confidence":"Medium","gaps":["Functional experiments centered on PP6c/PP6R3, not ANKRD44 specifically","Whether ANKRD44 is the relevant scaffold in this context untested"]},{"year":null,"claim":"Whether ANKRD44's distinct scaffolding role confers substrate or pathway specificity to PP6 beyond the interchangeable ankyrin family remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No ANKRD44-specific substrate or unique structural determinant identified","No structural model of the ANKRD44-containing heterotrimer","Distinct in vivo functions of ANKRD28 vs ANKRD44 vs ANKRD52 not separated"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1]}],"localization":[],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,3]}],"complexes":["PP6 holoenzyme (PP6c–PP6R1/R3–ANKRD44 heterotrimer)"],"partners":["PPP6C","PPP6R1","PPP6R3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8N8A2","full_name":"Serine/threonine-protein phosphatase 6 regulatory ankyrin repeat subunit B","aliases":["Ankyrin repeat domain-containing protein 44"],"length_aa":993,"mass_kda":107.6,"function":"Putative regulatory subunit of protein phosphatase 6 (PP6) that may be involved in the recognition of phosphoprotein substrates","subcellular_location":"","url":"https://www.uniprot.org/uniprotkb/Q8N8A2/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ANKRD44","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"ANKRD28","stoichiometry":0.2},{"gene":"PPP6R1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/ANKRD44","total_profiled":1310},"omim":[{"mim_id":"620862","title":"ANKYRIN REPEAT DOMAIN-CONTAINING PROTEIN 52; ANKRD52","url":"https://www.omim.org/entry/620862"},{"mim_id":"620861","title":"ANKYRIN REPEAT DOMAIN-CONTAINING PROTEIN 44; ANKRD44","url":"https://www.omim.org/entry/620861"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Mitochondria","reliability":"Approved"},{"location":"Nuclear speckles","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"lymphoid tissue","ntpm":34.2}],"url":"https://www.proteinatlas.org/search/ANKRD44"},"hgnc":{"alias_symbol":["PP6-ARS-B"],"prev_symbol":[]},"alphafold":{"accession":"Q8N8A2","domains":[{"cath_id":"1.25.40.20","chopping":"2-132","consensus_level":"medium","plddt":90.806,"start":2,"end":132},{"cath_id":"1.25.40.20","chopping":"139-232","consensus_level":"medium","plddt":97.2399,"start":139,"end":232},{"cath_id":"1.25.40.20","chopping":"570-663","consensus_level":"medium","plddt":90.5472,"start":570,"end":663},{"cath_id":"1.25.40.20","chopping":"737-789","consensus_level":"medium","plddt":90.0394,"start":737,"end":789}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8N8A2","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8N8A2-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8N8A2-F1-predicted_aligned_error_v6.png","plddt_mean":90.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ANKRD44","jax_strain_url":"https://www.jax.org/strain/search?query=ANKRD44"},"sequence":{"accession":"Q8N8A2","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8N8A2.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8N8A2/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8N8A2"}},"corpus_meta":[{"pmid":"18186651","id":"PMC_18186651","title":"Protein phosphatase 6 regulatory subunits composed of ankyrin repeat domains.","date":"2008","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/18186651","citation_count":96,"is_preprint":false},{"pmid":"25338677","id":"PMC_25338677","title":"Genetic analysis of the pathogenic molecular sub-phenotype interferon-alpha identifies multiple novel loci involved in systemic lupus erythematosus.","date":"2014","source":"Genes and immunity","url":"https://pubmed.ncbi.nlm.nih.gov/25338677","citation_count":59,"is_preprint":false},{"pmid":"32962511","id":"PMC_32962511","title":"Sex-specific associations with DNA methylation in lung tissue demonstrate smoking interactions.","date":"2020","source":"Epigenetics","url":"https://pubmed.ncbi.nlm.nih.gov/32962511","citation_count":32,"is_preprint":false},{"pmid":"38003134","id":"PMC_38003134","title":"Genomic Selection for Live Weight in the 14th Month in Alpine Merino Sheep Combining GWAS Information.","date":"2023","source":"Animals : an open access journal from MDPI","url":"https://pubmed.ncbi.nlm.nih.gov/38003134","citation_count":23,"is_preprint":false},{"pmid":"31297336","id":"PMC_31297336","title":"ANKRD44 Gene Silencing: A Putative Role in Trastuzumab Resistance in Her2-Like Breast Cancer.","date":"2019","source":"Frontiers in oncology","url":"https://pubmed.ncbi.nlm.nih.gov/31297336","citation_count":14,"is_preprint":false},{"pmid":"34350837","id":"PMC_34350837","title":"miR-133a-3p inhibits the osteogenic differentiation of bone marrow mesenchymal stem cells by regulating ankyrin repeat domain 44.","date":"2021","source":"General physiology and biophysics","url":"https://pubmed.ncbi.nlm.nih.gov/34350837","citation_count":8,"is_preprint":false},{"pmid":"38253780","id":"PMC_38253780","title":"Study on the expression changes of lncRNA in patients with systemic lupus erythematosus and its correlation with Treg cells.","date":"2024","source":"Clinical rheumatology","url":"https://pubmed.ncbi.nlm.nih.gov/38253780","citation_count":6,"is_preprint":false},{"pmid":"39014521","id":"PMC_39014521","title":"Protein phosphatase 6 promotes stemness of colorectal cancer cells.","date":"2024","source":"Cancer science","url":"https://pubmed.ncbi.nlm.nih.gov/39014521","citation_count":4,"is_preprint":false},{"pmid":"34115876","id":"PMC_34115876","title":"Identification of novel pleiotropic gene for bone mineral density and lean mass using the cFDR method.","date":"2021","source":"Annals of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/34115876","citation_count":4,"is_preprint":false},{"pmid":"36412907","id":"PMC_36412907","title":"Identification of Differentially Expressed Intronic Transcripts in Osteosarcoma.","date":"2022","source":"Non-coding RNA","url":"https://pubmed.ncbi.nlm.nih.gov/36412907","citation_count":4,"is_preprint":false},{"pmid":"31100866","id":"PMC_31100866","title":"Genome-Wide Association between the 2q33.1 Locus and Intracranial Aneurysm Susceptibility: An Updated Meta-Analysis Including 18,019 Individuals.","date":"2019","source":"Journal of clinical medicine","url":"https://pubmed.ncbi.nlm.nih.gov/31100866","citation_count":4,"is_preprint":false},{"pmid":"35552417","id":"PMC_35552417","title":"RNA-seq reveals insights into molecular mechanisms of metabolic restoration via tryptophan supplementation in low birth weight piglet model.","date":"2022","source":"Journal of animal science","url":"https://pubmed.ncbi.nlm.nih.gov/35552417","citation_count":3,"is_preprint":false},{"pmid":"40517592","id":"PMC_40517592","title":"A multi-phase approach using supervised algorithms and clinical models to generate high-accuracy signatures for pancreatic cancer.","date":"2025","source":"Computers in biology and medicine","url":"https://pubmed.ncbi.nlm.nih.gov/40517592","citation_count":1,"is_preprint":false},{"pmid":"31380291","id":"PMC_31380291","title":"Erratum: ANKRD44 Gene Silencing: A Putative Role in Trastuzumab Resistance in Her2-Like Breast Cancer.","date":"2019","source":"Frontiers in oncology","url":"https://pubmed.ncbi.nlm.nih.gov/31380291","citation_count":0,"is_preprint":false},{"pmid":"42217265","id":"PMC_42217265","title":"Metabolomics and transcriptomics profiling of the longissimus lumborum muscle reveals variations in the meat quality of rabbits at different ages.","date":"2026","source":"Meat science","url":"https://pubmed.ncbi.nlm.nih.gov/42217265","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10405,"output_tokens":1590,"usd":0.027533,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8415,"output_tokens":2214,"usd":0.048712,"stage2_stop_reason":"end_turn"},"total_usd":0.076245,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2008,\n      \"finding\": \"ANKRD44 (along with Ankrd28 and Ankrd52) was identified as an ankyrin repeat subunit of the PP6 holoenzyme complex. Tagged Ankrd28 (the closest characterized paralog used as proxy) coprecipitated with PP6 catalytic subunit but not PP2A or PP4, and with SAPS domain subunits PP6R1 and PP6R3. The C-terminal region of PP6R1 was sufficient to coprecipitate the ankyrin subunit but not PP6 itself, establishing PP6R1 as a scaffold with separate binding regions for PP6 and the ankyrin repeat subunit. Endogenous PP6 holoenzymes containing PP6R1, PP6R3, and Ankrd28 eluted at >440 kDa from Superose 12, consistent with a heterotrimer.\",\n      \"method\": \"FLAG co-immunoprecipitation, mass spectrometry, size-exclusion chromatography (Superose 12), domain-mapping pulldown with C-terminal PP6R1 fragment\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP with MS identification, domain-mapping, gel-filtration sizing, replicated across multiple tagged constructs and endogenous proteins in a single rigorous study\",\n      \"pmids\": [\"18186651\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Knockdown of PP6R1 or Ankrd28 (but not PP6R3) produced equivalent enhancement of IκBε degradation in response to TNFα, placing the PP6–PP6R1–Ankrd28/ANKRD44 complex upstream of IκBε stability in the NF-κB pathway.\",\n      \"method\": \"siRNA knockdown of individual PP6 complex subunits followed by TNFα stimulation and IκBε degradation assay\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean knockdown with defined pathway readout, single lab, two subunit comparisons providing specificity control\",\n      \"pmids\": [\"18186651\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"PP6 functions as a heterotrimer composed of PP6c catalytic subunit, a regulatory subunit (PP6R1–3), and a scaffold subunit (ANKRD28, ANKRD44, or ANKRD52). The PP6c–PP6R3 complex specifically regulates cancer stem cell (CSC) marker expression in colorectal cancer cells, and PP6c knockdown decreased colony-forming ability and in vivo proliferation.\",\n      \"method\": \"PP6c siRNA knockdown, transcriptome analysis, sphere-formation CSC assay, in vivo proliferation assay in CRC cell lines\",\n      \"journal\": \"Cancer science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional knockdown with transcriptome readout and in vivo validation, single lab; ANKRD44 named as scaffold subunit by established complex membership but functional experiments focused on PP6c/PP6R3\",\n      \"pmids\": [\"39014521\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Silencing of ANKRD44 in the HER2+ breast cancer cell line BT474 produced partial resistance to trastuzumab, constitutive activation of NF-κB via the TAK1/AKT pathway, increased glycolysis (evidenced by LDHB upregulation), and increased TROP2 expression.\",\n      \"method\": \"ANKRD44 siRNA silencing in BT474 cells, trastuzumab resistance assay, NF-κB activity measurement, LDHB and TROP2 Western blot, glycolysis assay\",\n      \"journal\": \"Frontiers in oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — loss-of-function with multiple downstream readouts (NF-κB, glycolysis, TROP2), single lab, no rescue experiment or pathway reconstruction in vitro\",\n      \"pmids\": [\"31297336\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"miR-133a-3p directly targets the ANKRD44 3′UTR (validated by dual luciferase assay) and negatively regulates ANKRD44 expression. Overexpression of ANKRD44 rescued the anti-osteogenic effects of miR-133a-3p in bone marrow mesenchymal stem cells, placing ANKRD44 downstream of miR-133a-3p in the osteogenic differentiation pathway.\",\n      \"method\": \"Dual luciferase reporter assay, qRT-PCR, Western blot, miR-133a-3p mimic/inhibitor transfection, ALP staining, alizarin red staining, ANKRD44 overexpression rescue experiment\",\n      \"journal\": \"General physiology and biophysics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct target validation by luciferase assay plus rescue experiment, single lab, multiple orthogonal readouts of osteogenic differentiation\",\n      \"pmids\": [\"34350837\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ANKRD44 is an ankyrin repeat scaffold subunit of the PP6 heterotrimer, binding to SAPS-domain regulatory subunits (PP6R1/R3) via a distinct region of PP6R1 to form a >440 kDa complex that is specific to PP6 (not PP2A or PP4) and regulates IκBε stability downstream of TNFα; loss of ANKRD44 also activates NF-κB via TAK1/AKT to promote trastuzumab resistance and increased glycolysis in HER2+ breast cancer cells, and ANKRD44 acts as a direct downstream target of miR-133a-3p to promote osteogenic differentiation of mesenchymal stem cells.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ANKRD44 is an ankyrin-repeat scaffold subunit of the protein phosphatase 6 (PP6) holoenzyme, one of three interchangeable ankyrin subunits (with ANKRD28 and ANKRD52) that assemble with the PP6 catalytic subunit and a SAPS-domain regulatory subunit (PP6R1–R3) into a >440 kDa heterotrimer specific to PP6 rather than PP2A or PP4 [#0, #2]. Within this complex, PP6R1 serves as the bridging scaffold, using a C-terminal region to recruit the ankyrin subunit through a site distinct from its PP6 catalytic-binding region [#0]. Functionally, the PP6–PP6R1–ankyrin complex restrains TNFα-induced degradation of IκBε, positioning ANKRD44 as a negative regulator of NF-κB signaling [#1]. Consistent with this role, ANKRD44 loss in HER2+ breast cancer cells drives constitutive NF-κB activation through the TAK1/AKT axis, increased glycolysis, and partial trastuzumab resistance [#3]. ANKRD44 is itself a direct target of miR-133a-3p, and its expression promotes osteogenic differentiation of bone marrow mesenchymal stem cells [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Establishing how the PP6 phosphatase is built, this work defined ANKRD44 as one of a family of ankyrin-repeat subunits that assemble with PP6 catalytic and SAPS-domain regulatory subunits into a specific heterotrimer.\",\n      \"evidence\": \"FLAG co-immunoprecipitation with mass spectrometry, size-exclusion chromatography, and domain-mapping pulldowns using a C-terminal PP6R1 fragment\",\n      \"pmids\": [\"18186651\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Most assembly data used ANKRD28 as proxy rather than ANKRD44 directly\", \"No structural model of the heterotrimer or the ankyrin–PP6R1 interface\", \"Functional distinction between the three interchangeable ankyrin subunits not resolved\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Linking the complex to a signaling output, knockdown placed the PP6–PP6R1–ankyrin assembly upstream of IκBε stability, implicating it as a brake on NF-κB activation.\",\n      \"evidence\": \"siRNA knockdown of individual PP6 subunits followed by TNFα stimulation and IκBε degradation assay\",\n      \"pmids\": [\"18186651\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct substrate of the phosphatase in this pathway not identified\", \"Effect attributed to ANKRD28; ANKRD44-specific contribution not isolated\", \"Single lab\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Extending the NF-κB link to cancer, ANKRD44 loss was shown to drive trastuzumab resistance via constitutive NF-κB activation and metabolic reprogramming in HER2+ breast cancer cells.\",\n      \"evidence\": \"ANKRD44 siRNA silencing in BT474 cells with trastuzumab resistance, NF-κB, glycolysis, LDHB and TROP2 readouts\",\n      \"pmids\": [\"31297336\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No rescue experiment to confirm specificity\", \"Connection to PP6 phosphatase activity not mechanistically reconstructed\", \"TAK1/AKT-to-NF-κB causal chain inferred from correlative readouts\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identifying an upstream regulator, ANKRD44 was validated as a direct miR-133a-3p target whose expression promotes osteogenic differentiation.\",\n      \"evidence\": \"Dual luciferase reporter assay, miR mimic/inhibitor transfection, and ANKRD44 overexpression rescue with ALP and alizarin red staining in BMSCs\",\n      \"pmids\": [\"34350837\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Downstream effector mechanism in osteogenesis not defined\", \"Whether PP6 complex assembly mediates the osteogenic effect untested\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Reaffirming complex architecture in a new context, the three-subunit PP6 composition was restated while CSC-regulatory function was attributed to the PP6c–PP6R3 pairing.\",\n      \"evidence\": \"PP6c siRNA knockdown, transcriptome analysis, sphere-formation and in vivo proliferation assays in colorectal cancer cells\",\n      \"pmids\": [\"39014521\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional experiments centered on PP6c/PP6R3, not ANKRD44 specifically\", \"Whether ANKRD44 is the relevant scaffold in this context untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Whether ANKRD44's distinct scaffolding role confers substrate or pathway specificity to PP6 beyond the interchangeable ankyrin family remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No ANKRD44-specific substrate or unique structural determinant identified\", \"No structural model of the ANKRD44-containing heterotrimer\", \"Distinct in vivo functions of ANKRD28 vs ANKRD44 vs ANKRD52 not separated\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 3]}\n    ],\n    \"complexes\": [\"PP6 holoenzyme (PP6c–PP6R1/R3–ANKRD44 heterotrimer)\"],\n    \"partners\": [\"PPP6C\", \"PPP6R1\", \"PPP6R3\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":5,"faith_pct":80.0}}