{"gene":"ACTRT3","run_date":"2026-04-28T17:12:37","timeline":{"discoveries":[{"year":2008,"finding":"Mouse ArpM1 (ACTRT3 ortholog) is expressed exclusively in the testis in haploid germ cells, localizes dynamically in the nucleus during spermiogenesis, and interacts with profilin III as identified by co-immunoprecipitation, suggesting the profilin III–ArpM1 complex is involved in conformational changes in sperm-specific nuclear organization.","method":"Co-immunoprecipitation, immunofluorescence localization","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 3 — single Co-IP identifying binding partner; localization data but mechanistic consequence is inferred","pmids":["18692047"],"is_preprint":false},{"year":2021,"finding":"ARPM1 (ACTRT3) is absent from the nuclear fraction of Pfn3-deficient testes and sperm, indicating that PFN3 stabilizes the PFN3–ARPM1 complex and that loss of PFN3 leads to destabilization and degradation of ARPM1.","method":"Co-immunoprecipitation, subcellular fractionation, CRISPR/Cas9 knockout mouse model","journal":"Frontiers in cell and developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 — clean KO with defined molecular phenotype (ARPM1 loss from nuclear fraction) and Co-IP in a single study","pmids":["34869336"],"is_preprint":false},{"year":2026,"finding":"ACTRT3 localizes to the perinuclear theca (PT) of murine spermatids; Actrt3 knockout males are subfertile with acrosome biogenesis defects starting at cap phase, reduced levels of trans-Golgi markers TGN46 and GOPC, and mislocalization of cis-Golgi protein GM130, indicating ACTRT3 is required for Golgi trafficking and autophagic flux during acrosome biogenesis.","method":"CRISPR/Cas9 knockout mouse, immunofluorescence localization, western blotting","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 — clean KO with multiple defined molecular and cellular phenotypes, replicated independently from preprint data","pmids":["41668650"],"is_preprint":false},{"year":2026,"finding":"ACTRT3 physically interacts with perinuclear theca proteins ACTRT1, ACTRT2, ACTL7A, SPEM2, and sperm surface protein ZPBP, as revealed by co-immunoprecipitation, suggesting ACTRT3 is a structural component of the PT 3D scaffold and contributes to ZPBP localization.","method":"Co-immunoprecipitation","journal":"Development (Cambridge, England)","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP identifying multiple binding partners in a single study","pmids":["41668650"],"is_preprint":false},{"year":2026,"finding":"Mass spectrometry of ACTRT3-associated proteins revealed enrichment of cytoskeletal regulators including CFL1 and CNN1, and overexpression of Actrt3 in HEK293T cells caused changes in cell shape and F-actin filament distribution, indicating a role for ACTRT3 in cytoskeletal remodeling.","method":"Mass spectrometry, overexpression in HEK293T cells with F-actin staining","journal":"Development (Cambridge, England)","confidence":"Medium","confidence_rationale":"Tier 2 — mass spectrometry interactome combined with functional cell-based assay in a single study","pmids":["41668650"],"is_preprint":false},{"year":2025,"finding":"ARPM1 (ACTRT3) interacts with PT-specific proteins ACTRT1, ACTRT2, ACTL7A, and sperm surface protein ZPBP by co-immunoprecipitation; Arpm1-/- mice are subfertile with acrosomal morphological aberrations and deregulation of GM130 and TGN46, supporting ARPM1 as a structural PT component that mediates ZPBP localization and tethers PFN3 to regulate Golgi-related acrosome development.","method":"CRISPR/Cas9 knockout mouse, co-immunoprecipitation, immunofluorescence","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 — clean KO with defined phenotypes and Co-IP; preprint, largely consistent with peer-reviewed paper","pmids":["bio_10.1101_2025.03.27.645694"],"is_preprint":true}],"current_model":"ACTRT3 (ARPM1) is a testis-enriched actin-related protein that localizes to the perinuclear theca of spermatids, where it forms a complex with profilin III (PFN3) and PT scaffold proteins (ACTRT1, ACTRT2, ACTL7A, SPEM2) and the sperm surface protein ZPBP; it is required for proper Golgi trafficking, autophagic flux, and acrosome biogenesis during spermiogenesis, and influences F-actin organization, with its loss causing subfertility and acrosomal defects in mice."},"narrative":{"teleology":[{"year":2008,"claim":"Establishing that ACTRT3 is a testis-specific, haploid germ cell protein that physically associates with profilin III resolved its tissue expression and identified a first binding partner, suggesting a role in sperm nuclear organization.","evidence":"Co-immunoprecipitation and immunofluorescence in mouse testis","pmids":["18692047"],"confidence":"Medium","gaps":["Single Co-IP without reciprocal validation","Functional consequence of the PFN3–ACTRT3 interaction was not tested","No loss-of-function model"]},{"year":2021,"claim":"Demonstrating that PFN3 is required to stabilize ACTRT3 in the nuclear fraction established a dependency relationship within the PFN3–ACTRT3 complex and showed that ACTRT3 protein fate is controlled by its binding partner.","evidence":"Subcellular fractionation and Co-IP in Pfn3-knockout mouse testes (CRISPR/Cas9)","pmids":["34869336"],"confidence":"Medium","gaps":["Mechanism of ACTRT3 degradation upon PFN3 loss (proteasomal vs. autophagic) not determined","Whether ACTRT3 loss mediates any of the Pfn3-KO phenotypes was not tested"]},{"year":2026,"claim":"An Actrt3 knockout mouse revealed that ACTRT3 localizes to the perinuclear theca, is required for acrosome biogenesis from the cap phase onward, and controls Golgi organization and autophagic flux, establishing the first direct loss-of-function phenotype and defining its cellular role in spermiogenesis.","evidence":"CRISPR/Cas9 Actrt3-knockout mouse with immunofluorescence, western blotting for Golgi markers (TGN46, GOPC, GM130)","pmids":["41668650"],"confidence":"High","gaps":["How ACTRT3 mechanistically regulates Golgi trafficking is unresolved","Whether the subfertility phenotype is solely acrosome-dependent or also involves other sperm functions is not addressed"]},{"year":2026,"claim":"Identification of ACTRT3 interactions with multiple PT proteins (ACTRT1, ACTRT2, ACTL7A, SPEM2) and the sperm surface protein ZPBP positioned ACTRT3 as a hub within the PT scaffold that contributes to ZPBP surface localization and overall PT architecture.","evidence":"Co-immunoprecipitation from testis lysates","pmids":["41668650"],"confidence":"Medium","gaps":["Co-IPs lack reciprocal pull-downs for all partners","Stoichiometry and direct vs. indirect nature of each interaction not resolved","How ZPBP localization depends on ACTRT3 scaffolding is not mechanistically defined"]},{"year":2026,"claim":"Mass spectrometry interactome analysis and overexpression studies demonstrated that ACTRT3 associates with cytoskeletal regulators (CFL1, CNN1) and can remodel F-actin, extending its function beyond a static scaffold to an active participant in cytoskeletal dynamics.","evidence":"Mass spectrometry of ACTRT3-associated proteins; F-actin staining after ACTRT3 overexpression in HEK293T cells","pmids":["41668650"],"confidence":"Medium","gaps":["F-actin remodeling shown only in a heterologous cell line, not in spermatids","Whether cytoskeletal regulation is separable from Golgi/acrosome function is unknown","No structural data on ACTRT3 or its actin-fold properties"]},{"year":null,"claim":"The mechanism by which ACTRT3 coordinates Golgi trafficking and autophagic flux during acrosome biogenesis remains undefined, as does whether its cytoskeletal remodeling activity directly drives acrosome vesicle transport.","evidence":"","pmids":[],"confidence":"High","gaps":["No structural model of ACTRT3 or its complexes exists","Molecular basis of Golgi trafficking control (cargo adaptors, membrane tethers) is unknown","Whether ACTRT3 mutations contribute to human male infertility has not been tested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[4]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,1,2]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[2]}],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[0,2]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[2]}],"complexes":[],"partners":["PFN3","ACTRT1","ACTRT2","ACTL7A","SPEM2","ZPBP","CFL1","CNN1"],"other_free_text":[]},"mechanistic_narrative":"ACTRT3 (ARPM1) is a testis-specific actin-related protein that functions as a structural component of the perinuclear theca (PT) during spermiogenesis, where it is required for Golgi trafficking, autophagic flux, and acrosome biogenesis. ACTRT3 forms a complex with profilin III (PFN3), which stabilizes ACTRT3 in the nuclear fraction; loss of PFN3 leads to ACTRT3 destabilization and degradation [PMID:18692047, PMID:34869336]. ACTRT3 physically interacts with PT scaffold proteins ACTRT1, ACTRT2, ACTL7A, and SPEM2, as well as the sperm surface protein ZPBP, and its knockout in mice causes subfertility with acrosomal defects beginning at cap phase, reduced trans-Golgi markers TGN46 and GOPC, and mislocalization of cis-Golgi protein GM130 [PMID:41668650]. ACTRT3 also influences F-actin organization, with its interactome enriched for cytoskeletal regulators including CFL1 and CNN1 [PMID:41668650]."},"prefetch_data":{"uniprot":{"accession":"Q9BYD9","full_name":"Actin-related protein T3","aliases":["Actin-related protein M1"],"length_aa":372,"mass_kda":41.0,"function":"","subcellular_location":"Cytoplasm, cytoskeleton; Cytoplasm; Nucleus","url":"https://www.uniprot.org/uniprotkb/Q9BYD9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ACTRT3","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/ACTRT3","total_profiled":1310},"omim":[{"mim_id":"608534","title":"ACTIN-RELATED PROTEIN T3; ACTRT3","url":"https://www.omim.org/entry/608534"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Centrosome","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"},{"location":"Acrosome","reliability":"Additional"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"testis","ntpm":54.1}],"url":"https://www.proteinatlas.org/search/ACTRT3"},"hgnc":{"alias_symbol":["ARPM1"],"prev_symbol":[]},"alphafold":{"accession":"Q9BYD9","domains":[{"cath_id":"3.30.420.40","chopping":"9-137_335-372","consensus_level":"medium","plddt":92.6333,"start":9,"end":372},{"cath_id":"3.30.420.40","chopping":"143-180_269-328","consensus_level":"medium","plddt":97.4665,"start":143,"end":328},{"cath_id":"3.90.640.10","chopping":"182-264","consensus_level":"high","plddt":95.1876,"start":182,"end":264}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BYD9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BYD9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BYD9-F1-predicted_aligned_error_v6.png","plddt_mean":94.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ACTRT3","jax_strain_url":"https://www.jax.org/strain/search?query=ACTRT3"},"sequence":{"accession":"Q9BYD9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9BYD9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9BYD9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BYD9"}},"corpus_meta":[{"pmid":"18692047","id":"PMC_18692047","title":"Nuclear localization of profilin III-ArpM1 complex in mouse spermiogenesis.","date":"2008","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/18692047","citation_count":26,"is_preprint":false},{"pmid":"34869336","id":"PMC_34869336","title":"Loss of Profilin3 Impairs Spermiogenesis by Affecting Acrosome Biogenesis, Autophagy, Manchette Development and Mitochondrial Organization.","date":"2021","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/34869336","citation_count":21,"is_preprint":false},{"pmid":"39425105","id":"PMC_39425105","title":"Plasma genome-wide mendelian randomization identifies potentially causal genes in idiopathic pulmonary fibrosis.","date":"2024","source":"Respiratory research","url":"https://pubmed.ncbi.nlm.nih.gov/39425105","citation_count":4,"is_preprint":false},{"pmid":"31524152","id":"PMC_31524152","title":"Assessment of the genes and molecular mechanisms of B cells activation through systems biology approaches.","date":"2020","source":"Human antibodies","url":"https://pubmed.ncbi.nlm.nih.gov/31524152","citation_count":0,"is_preprint":false},{"pmid":"41668650","id":"PMC_41668650","title":"Actin-related protein T3 is required for acrosome biogenesis and sperm function in mice.","date":"2026","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/41668650","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.03.27.645694","title":"Actin-related protein M1 (ARPM1) required for acrosome biogenesis and sperm function in mice","date":"2025-04-01","source":"bioRxiv","url":"https://doi.org/10.1101/2025.03.27.645694","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.10.29.24316326","title":"Unraveling the genetic landscape of susceptibility to multiple primary cancers","date":"2024-10-30","source":"bioRxiv","url":"https://doi.org/10.1101/2024.10.29.24316326","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":5232,"output_tokens":1501,"usd":0.019106},"stage2":{"model":"claude-opus-4-6","input_tokens":4742,"output_tokens":1770,"usd":0.10194},"total_usd":0.121046,"stage1_batch_id":"msgbatch_01TqNM6p6FsoMBT2jzQTwKBr","stage2_batch_id":"msgbatch_01Ya473eco8sTHbvRymQaU8o","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2008,\n      \"finding\": \"Mouse ArpM1 (ACTRT3 ortholog) is expressed exclusively in the testis in haploid germ cells, localizes dynamically in the nucleus during spermiogenesis, and interacts with profilin III as identified by co-immunoprecipitation, suggesting the profilin III–ArpM1 complex is involved in conformational changes in sperm-specific nuclear organization.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence localization\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single Co-IP identifying binding partner; localization data but mechanistic consequence is inferred\",\n      \"pmids\": [\"18692047\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"ARPM1 (ACTRT3) is absent from the nuclear fraction of Pfn3-deficient testes and sperm, indicating that PFN3 stabilizes the PFN3–ARPM1 complex and that loss of PFN3 leads to destabilization and degradation of ARPM1.\",\n      \"method\": \"Co-immunoprecipitation, subcellular fractionation, CRISPR/Cas9 knockout mouse model\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined molecular phenotype (ARPM1 loss from nuclear fraction) and Co-IP in a single study\",\n      \"pmids\": [\"34869336\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"ACTRT3 localizes to the perinuclear theca (PT) of murine spermatids; Actrt3 knockout males are subfertile with acrosome biogenesis defects starting at cap phase, reduced levels of trans-Golgi markers TGN46 and GOPC, and mislocalization of cis-Golgi protein GM130, indicating ACTRT3 is required for Golgi trafficking and autophagic flux during acrosome biogenesis.\",\n      \"method\": \"CRISPR/Cas9 knockout mouse, immunofluorescence localization, western blotting\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with multiple defined molecular and cellular phenotypes, replicated independently from preprint data\",\n      \"pmids\": [\"41668650\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"ACTRT3 physically interacts with perinuclear theca proteins ACTRT1, ACTRT2, ACTL7A, SPEM2, and sperm surface protein ZPBP, as revealed by co-immunoprecipitation, suggesting ACTRT3 is a structural component of the PT 3D scaffold and contributes to ZPBP localization.\",\n      \"method\": \"Co-immunoprecipitation\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP identifying multiple binding partners in a single study\",\n      \"pmids\": [\"41668650\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Mass spectrometry of ACTRT3-associated proteins revealed enrichment of cytoskeletal regulators including CFL1 and CNN1, and overexpression of Actrt3 in HEK293T cells caused changes in cell shape and F-actin filament distribution, indicating a role for ACTRT3 in cytoskeletal remodeling.\",\n      \"method\": \"Mass spectrometry, overexpression in HEK293T cells with F-actin staining\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — mass spectrometry interactome combined with functional cell-based assay in a single study\",\n      \"pmids\": [\"41668650\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"ARPM1 (ACTRT3) interacts with PT-specific proteins ACTRT1, ACTRT2, ACTL7A, and sperm surface protein ZPBP by co-immunoprecipitation; Arpm1-/- mice are subfertile with acrosomal morphological aberrations and deregulation of GM130 and TGN46, supporting ARPM1 as a structural PT component that mediates ZPBP localization and tethers PFN3 to regulate Golgi-related acrosome development.\",\n      \"method\": \"CRISPR/Cas9 knockout mouse, co-immunoprecipitation, immunofluorescence\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined phenotypes and Co-IP; preprint, largely consistent with peer-reviewed paper\",\n      \"pmids\": [\"bio_10.1101_2025.03.27.645694\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"ACTRT3 (ARPM1) is a testis-enriched actin-related protein that localizes to the perinuclear theca of spermatids, where it forms a complex with profilin III (PFN3) and PT scaffold proteins (ACTRT1, ACTRT2, ACTL7A, SPEM2) and the sperm surface protein ZPBP; it is required for proper Golgi trafficking, autophagic flux, and acrosome biogenesis during spermiogenesis, and influences F-actin organization, with its loss causing subfertility and acrosomal defects in mice.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"ACTRT3 (ARPM1) is a testis-specific actin-related protein that functions as a structural component of the perinuclear theca (PT) during spermiogenesis, where it is required for Golgi trafficking, autophagic flux, and acrosome biogenesis. ACTRT3 forms a complex with profilin III (PFN3), which stabilizes ACTRT3 in the nuclear fraction; loss of PFN3 leads to ACTRT3 destabilization and degradation [PMID:18692047, PMID:34869336]. ACTRT3 physically interacts with PT scaffold proteins ACTRT1, ACTRT2, ACTL7A, and SPEM2, as well as the sperm surface protein ZPBP, and its knockout in mice causes subfertility with acrosomal defects beginning at cap phase, reduced trans-Golgi markers TGN46 and GOPC, and mislocalization of cis-Golgi protein GM130 [PMID:41668650]. ACTRT3 also influences F-actin organization, with its interactome enriched for cytoskeletal regulators including CFL1 and CNN1 [PMID:41668650].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Establishing that ACTRT3 is a testis-specific, haploid germ cell protein that physically associates with profilin III resolved its tissue expression and identified a first binding partner, suggesting a role in sperm nuclear organization.\",\n      \"evidence\": \"Co-immunoprecipitation and immunofluorescence in mouse testis\",\n      \"pmids\": [\"18692047\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single Co-IP without reciprocal validation\",\n        \"Functional consequence of the PFN3–ACTRT3 interaction was not tested\",\n        \"No loss-of-function model\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Demonstrating that PFN3 is required to stabilize ACTRT3 in the nuclear fraction established a dependency relationship within the PFN3–ACTRT3 complex and showed that ACTRT3 protein fate is controlled by its binding partner.\",\n      \"evidence\": \"Subcellular fractionation and Co-IP in Pfn3-knockout mouse testes (CRISPR/Cas9)\",\n      \"pmids\": [\"34869336\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism of ACTRT3 degradation upon PFN3 loss (proteasomal vs. autophagic) not determined\",\n        \"Whether ACTRT3 loss mediates any of the Pfn3-KO phenotypes was not tested\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"An Actrt3 knockout mouse revealed that ACTRT3 localizes to the perinuclear theca, is required for acrosome biogenesis from the cap phase onward, and controls Golgi organization and autophagic flux, establishing the first direct loss-of-function phenotype and defining its cellular role in spermiogenesis.\",\n      \"evidence\": \"CRISPR/Cas9 Actrt3-knockout mouse with immunofluorescence, western blotting for Golgi markers (TGN46, GOPC, GM130)\",\n      \"pmids\": [\"41668650\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"How ACTRT3 mechanistically regulates Golgi trafficking is unresolved\",\n        \"Whether the subfertility phenotype is solely acrosome-dependent or also involves other sperm functions is not addressed\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Identification of ACTRT3 interactions with multiple PT proteins (ACTRT1, ACTRT2, ACTL7A, SPEM2) and the sperm surface protein ZPBP positioned ACTRT3 as a hub within the PT scaffold that contributes to ZPBP surface localization and overall PT architecture.\",\n      \"evidence\": \"Co-immunoprecipitation from testis lysates\",\n      \"pmids\": [\"41668650\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Co-IPs lack reciprocal pull-downs for all partners\",\n        \"Stoichiometry and direct vs. indirect nature of each interaction not resolved\",\n        \"How ZPBP localization depends on ACTRT3 scaffolding is not mechanistically defined\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Mass spectrometry interactome analysis and overexpression studies demonstrated that ACTRT3 associates with cytoskeletal regulators (CFL1, CNN1) and can remodel F-actin, extending its function beyond a static scaffold to an active participant in cytoskeletal dynamics.\",\n      \"evidence\": \"Mass spectrometry of ACTRT3-associated proteins; F-actin staining after ACTRT3 overexpression in HEK293T cells\",\n      \"pmids\": [\"41668650\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"F-actin remodeling shown only in a heterologous cell line, not in spermatids\",\n        \"Whether cytoskeletal regulation is separable from Golgi/acrosome function is unknown\",\n        \"No structural data on ACTRT3 or its actin-fold properties\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The mechanism by which ACTRT3 coordinates Golgi trafficking and autophagic flux during acrosome biogenesis remains undefined, as does whether its cytoskeletal remodeling activity directly drives acrosome vesicle transport.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No structural model of ACTRT3 or its complexes exists\",\n        \"Molecular basis of Golgi trafficking control (cargo adaptors, membrane tethers) is unknown\",\n        \"Whether ACTRT3 mutations contribute to human male infertility has not been tested\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"PFN3\", \"ACTRT1\", \"ACTRT2\", \"ACTL7A\", \"SPEM2\", \"ZPBP\", \"CFL1\", \"CNN1\"],\n    \"other_free_text\": []\n  }\n}\n```"}