{"gene":"ACTL9","run_date":"2026-04-28T17:12:37","timeline":{"discoveries":[{"year":2022,"finding":"ACTL9 protein interacts with ACTRT1, ACTRT2, and ACTL7A to form a multimeric complex that localizes to the subacrosomal region of spermatids, where this complex mediates the acrosome-nucleus connection.","method":"Co-immunoprecipitation, immunostaining, and genetic knockout mouse model","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 — reciprocal protein interaction demonstrated with KO phenotypic validation, replicated across multiple studies","pmids":["35616329"],"is_preprint":false},{"year":2022,"finding":"ACTL9 is a phosphorylation substrate of testis-specific serine kinase 3 (TSSK3); loss of TSSK3 results in significantly reduced phosphorylation of ACTL9 in germ cells without altering total ACTL9 protein levels.","method":"Phosphoproteomics of purified germ cells from Tssk3 knockout vs. heterozygous mice","journal":"Andrology","confidence":"Medium","confidence_rationale":"Tier 2 — phosphoproteomic mass spectrometry in KO model, single study","pmids":["36306217"],"is_preprint":false},{"year":2024,"finding":"CABS1, a perinuclear theca protein, physically interacts with ACTL9; a nonsense mutation in CABS1 reduces this interaction, leading to acrosome absence, abnormal PLCζ localization, and total fertilization failure.","method":"Co-immunoprecipitation of wild-type vs. mutant CABS1 with ACTL9, immunofluorescence, western blot","journal":"Journal of assisted reproduction and genetics","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP with mutant comparison and functional readout, single study","pmids":["40407971"],"is_preprint":false},{"year":2024,"finding":"Homozygous mutations in ACTL9 cause irregular mitochondrial sheath arrangement and abnormal '9+2' axonemal structure in sperm flagella, leading to reduced sperm motility and abnormal sperm morphology; an Actl9 knock-in mouse model recapitulated these flagellar ultrastructural defects.","method":"Whole-exome sequencing, scanning and transmission electron microscopy, CASA, Actl9 knock-in mouse model, immunostaining","journal":"Journal of assisted reproduction and genetics","confidence":"Medium","confidence_rationale":"Tier 2 — KO/KI animal model with ultrastructural validation, single lab","pmids":["38963606"],"is_preprint":false},{"year":2024,"finding":"ACTL9 localizes to the subacrosomal perinuclear theca region of spermatids, and loss-of-function variants in ACTL9 result in fertilization failure after ICSI, consistent with a role in the acrosomal complex required for sperm-egg fusion.","method":"Immunostaining of patient sperm, whole-exome sequencing with segregation analysis, ICSI outcome data","journal":"Molecular genetics & genomic medicine","confidence":"Low","confidence_rationale":"Tier 3 — single patient variant with in silico and localization data, no direct functional rescue","pmids":["38769899"],"is_preprint":false}],"current_model":"ACTL9 is a sperm-specific actin-related protein that forms a multimeric complex with ACTRT1, ACTRT2, and ACTL7A in the subacrosomal perinuclear theca of spermatids, where it anchors the acrosome to the nucleus, supports proper flagellar axonemal and mitochondrial sheath assembly, and undergoes TSSK3-mediated phosphorylation; loss-of-function mutations cause acrosomal detachment, flagellar ultrastructural defects, and complete fertilization failure."},"narrative":{"teleology":[{"year":2022,"claim":"Identifying ACTL9 as part of a subacrosomal multimeric complex with ACTRT1, ACTRT2, and ACTL7A established its primary molecular function: mediating the physical connection between the acrosome and the nucleus in spermatids.","evidence":"Co-immunoprecipitation, immunostaining, and genetic knockout mouse model in Development","pmids":["35616329"],"confidence":"High","gaps":["Stoichiometry and assembly order of the ACTL9–ACTRT1–ACTRT2–ACTL7A complex are unknown","No structural model of the complex exists","Whether ACTL9 has intrinsic actin-like ATPase or filament-forming activity has not been tested"]},{"year":2022,"claim":"Phosphoproteomic analysis of Tssk3-knockout germ cells revealed ACTL9 as a TSSK3 phosphorylation substrate, establishing a post-translational regulatory axis for the subacrosomal complex during spermiogenesis.","evidence":"Phosphoproteomics of purified germ cells from Tssk3-KO vs. heterozygous mice","pmids":["36306217"],"confidence":"Medium","gaps":["The specific phosphorylation site(s) on ACTL9 and their functional consequences have not been determined","Whether TSSK3-mediated phosphorylation modulates ACTL9 complex assembly or stability is untested","No in vitro kinase assay confirming direct phosphorylation"]},{"year":2024,"claim":"Discovery that homozygous ACTL9 mutations cause flagellar ultrastructural defects—irregular mitochondrial sheath and abnormal 9+2 axoneme—expanded ACTL9's role beyond acrosomal anchoring to flagellar assembly and sperm motility.","evidence":"Whole-exome sequencing, TEM/SEM of patient and knock-in mouse sperm, CASA motility analysis","pmids":["38963606"],"confidence":"Medium","gaps":["Whether ACTL9 acts directly in flagellar assembly or the defect is secondary to perinuclear theca disruption is unclear","Single-lab study; independent replication in additional cohorts not yet reported","Molecular partners of ACTL9 in the flagellar compartment are unidentified"]},{"year":2024,"claim":"Identification of CABS1 as an ACTL9-interacting partner, and demonstration that a CABS1 nonsense mutation disrupts this interaction and causes acrosome absence with fertilization failure, linked the ACTL9 interaction network to oocyte activation (via PLCζ mislocalization).","evidence":"Co-IP of wild-type vs. mutant CABS1 with ACTL9, immunofluorescence, western blot","pmids":["40407971"],"confidence":"Medium","gaps":["Whether ACTL9 directly recruits PLCζ or the effect is indirect through CABS1 is unknown","Single study without reciprocal ACTL9 perturbation to confirm directionality","Binding domain mapping between ACTL9 and CABS1 has not been performed"]},{"year":null,"claim":"It remains unknown whether ACTL9 possesses intrinsic actin-like biochemical activities (ATPase, polymerization), how TSSK3 phosphorylation regulates complex dynamics, and whether ACTL9's flagellar role is direct or secondary to perinuclear theca disruption.","evidence":"","pmids":[],"confidence":"Low","gaps":["No in vitro biochemical characterization of ACTL9","No high-resolution structural data for ACTL9 or its complexes","Causal relationship between ACTL9 loss and flagellar vs. acrosomal defects not dissected"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,4]}],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[0,3]}],"complexes":["ACTRT1–ACTRT2–ACTL7A–ACTL9 subacrosomal complex"],"partners":["ACTRT1","ACTRT2","ACTL7A","CABS1","TSSK3"],"other_free_text":[]},"mechanistic_narrative":"ACTL9 is a testis-specific actin-related protein that localizes to the subacrosomal perinuclear theca of spermatids, where it forms a multimeric complex with ACTRT1, ACTRT2, and ACTL7A to anchor the acrosome to the nucleus [PMID:35616329]. ACTL9 also interacts with CABS1, and disruption of this interaction leads to acrosome absence, abnormal PLCζ localization, and total fertilization failure [PMID:40407971]. Beyond acrosomal attachment, ACTL9 is required for proper flagellar axonemal organization and mitochondrial sheath assembly, and homozygous loss-of-function mutations cause asthenoteratozoospermia and fertilization failure in both humans and knock-in mouse models [PMID:38963606]. ACTL9 undergoes TSSK3-mediated phosphorylation in germ cells, indicating post-translational regulation of its function during spermiogenesis [PMID:36306217]."},"prefetch_data":{"uniprot":{"accession":"Q8TC94","full_name":"Actin-like protein 9","aliases":[],"length_aa":416,"mass_kda":45.5,"function":"Testis-specic protein that plays an important role in fusion of proacrosomal vesicles and perinuclear theca formation","subcellular_location":"Cytoplasmic vesicle, secretory vesicle, acrosome; Cytoplasm, cytoskeleton, perinuclear theca","url":"https://www.uniprot.org/uniprotkb/Q8TC94/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ACTL9","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":[],"url":"https://opencell.sf.czbiohub.org/search/ACTL9","total_profiled":1310},"omim":[{"mim_id":"619258","title":"SPERMATOGENIC FAILURE 53; SPGF53","url":"https://www.omim.org/entry/619258"},{"mim_id":"619251","title":"ACTIN-LIKE 9; ACTL9","url":"https://www.omim.org/entry/619251"},{"mim_id":"604303","title":"ACTIN-LIKE 7A; ACTL7A","url":"https://www.omim.org/entry/604303"},{"mim_id":"300487","title":"ACTIN-RELATED PROTEIN T1; ACTRT1","url":"https://www.omim.org/entry/300487"},{"mim_id":"258150","title":"SPERMATOGENIC FAILURE 1; SPGF1","url":"https://www.omim.org/entry/258150"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Acrosome","reliability":"Supported"},{"location":"Equatorial segment","reliability":"Supported"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in single","driving_tissues":[{"tissue":"testis","ntpm":108.2}],"url":"https://www.proteinatlas.org/search/ACTL9"},"hgnc":{"alias_symbol":["MGC33407"],"prev_symbol":[]},"alphafold":{"accession":"Q8TC94","domains":[{"cath_id":"3.30.420.40","chopping":"51-182_380-412","consensus_level":"medium","plddt":91.4415,"start":51,"end":412},{"cath_id":"3.90.640.10","chopping":"224-299","consensus_level":"high","plddt":91.3493,"start":224,"end":299}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TC94","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TC94-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TC94-F1-predicted_aligned_error_v6.png","plddt_mean":87.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ACTL9","jax_strain_url":"https://www.jax.org/strain/search?query=ACTL9"},"sequence":{"accession":"Q8TC94","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8TC94.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8TC94/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TC94"}},"corpus_meta":[{"pmid":"37758324","id":"PMC_37758324","title":"Genetic mechanisms of fertilization failure and early embryonic arrest: a comprehensive review.","date":"2024","source":"Human reproduction update","url":"https://pubmed.ncbi.nlm.nih.gov/37758324","citation_count":49,"is_preprint":false},{"pmid":"35616329","id":"PMC_35616329","title":"Loss of perinuclear theca ACTRT1 causes acrosome detachment and severe male subfertility in mice.","date":"2022","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/35616329","citation_count":29,"is_preprint":false},{"pmid":"36306217","id":"PMC_36306217","title":"Testis-specific serine kinase 3 is required for sperm morphogenesis and male fertility.","date":"2022","source":"Andrology","url":"https://pubmed.ncbi.nlm.nih.gov/36306217","citation_count":25,"is_preprint":false},{"pmid":"36589837","id":"PMC_36589837","title":"Gene mutations associated with fertilization failure after in vitro fertilization/intracytoplasmic sperm injection.","date":"2022","source":"Frontiers in endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/36589837","citation_count":19,"is_preprint":false},{"pmid":"23278845","id":"PMC_23278845","title":"Association of KIF3A, but not OVOL1 and ACTL9, with atopic eczema in Italian patients.","date":"2013","source":"The British journal of dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/23278845","citation_count":16,"is_preprint":false},{"pmid":"33707600","id":"PMC_33707600","title":"Establishment and genomic characterization of a sporadic malignant peripheral nerve sheath tumor cell line.","date":"2021","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/33707600","citation_count":15,"is_preprint":false},{"pmid":"38414365","id":"PMC_38414365","title":"Deletion of ACTRT1 is associated with male infertility as sperm acrosomal ultrastructural defects and fertilization failure in human.","date":"2024","source":"Human reproduction (Oxford, England)","url":"https://pubmed.ncbi.nlm.nih.gov/38414365","citation_count":11,"is_preprint":false},{"pmid":"37118964","id":"PMC_37118964","title":"Differential Proteomic Analysis of Human Sperm: A Systematic Review to Identify Candidate Targets to Monitor Sperm Quality.","date":"2023","source":"The world journal of men's health","url":"https://pubmed.ncbi.nlm.nih.gov/37118964","citation_count":8,"is_preprint":false},{"pmid":"37212058","id":"PMC_37212058","title":"Exonic genetic variants associated with unexpected fertilization failure and zygotic arrest after ICSI: a systematic review.","date":"2023","source":"Zygote (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/37212058","citation_count":6,"is_preprint":false},{"pmid":"38769899","id":"PMC_38769899","title":"Identification of a new mutation in the ACTL9 gene in men with unexplained infertility.","date":"2024","source":"Molecular genetics & genomic medicine","url":"https://pubmed.ncbi.nlm.nih.gov/38769899","citation_count":2,"is_preprint":false},{"pmid":"38963606","id":"PMC_38963606","title":"Homozygous ACTL9 mutations cause irregular mitochondrial sheath arrangement and abnormal flagellum assembly in spermatozoa and male infertility.","date":"2024","source":"Journal of assisted reproduction and genetics","url":"https://pubmed.ncbi.nlm.nih.gov/38963606","citation_count":2,"is_preprint":false},{"pmid":"40407971","id":"PMC_40407971","title":"Identification of nonfunctional CABS1 causing fertilization failure and male infertility in humans: a case report.","date":"2025","source":"Journal of assisted reproduction and genetics","url":"https://pubmed.ncbi.nlm.nih.gov/40407971","citation_count":1,"is_preprint":false},{"pmid":"40376536","id":"PMC_40376536","title":"Establishment and clinical significance of genetic factor screening method for patients with nonobstructive azoospermia based on whole exon sequencing technology.","date":"2025","source":"Translational andrology and urology","url":"https://pubmed.ncbi.nlm.nih.gov/40376536","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8700,"output_tokens":1131,"usd":0.021532},"stage2":{"model":"claude-opus-4-6","input_tokens":4352,"output_tokens":1586,"usd":0.092115},"total_usd":0.113647,"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\": 2022,\n      \"finding\": \"ACTL9 protein interacts with ACTRT1, ACTRT2, and ACTL7A to form a multimeric complex that localizes to the subacrosomal region of spermatids, where this complex mediates the acrosome-nucleus connection.\",\n      \"method\": \"Co-immunoprecipitation, immunostaining, and genetic knockout mouse model\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal protein interaction demonstrated with KO phenotypic validation, replicated across multiple studies\",\n      \"pmids\": [\"35616329\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ACTL9 is a phosphorylation substrate of testis-specific serine kinase 3 (TSSK3); loss of TSSK3 results in significantly reduced phosphorylation of ACTL9 in germ cells without altering total ACTL9 protein levels.\",\n      \"method\": \"Phosphoproteomics of purified germ cells from Tssk3 knockout vs. heterozygous mice\",\n      \"journal\": \"Andrology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — phosphoproteomic mass spectrometry in KO model, single study\",\n      \"pmids\": [\"36306217\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CABS1, a perinuclear theca protein, physically interacts with ACTL9; a nonsense mutation in CABS1 reduces this interaction, leading to acrosome absence, abnormal PLCζ localization, and total fertilization failure.\",\n      \"method\": \"Co-immunoprecipitation of wild-type vs. mutant CABS1 with ACTL9, immunofluorescence, western blot\",\n      \"journal\": \"Journal of assisted reproduction and genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP with mutant comparison and functional readout, single study\",\n      \"pmids\": [\"40407971\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Homozygous mutations in ACTL9 cause irregular mitochondrial sheath arrangement and abnormal '9+2' axonemal structure in sperm flagella, leading to reduced sperm motility and abnormal sperm morphology; an Actl9 knock-in mouse model recapitulated these flagellar ultrastructural defects.\",\n      \"method\": \"Whole-exome sequencing, scanning and transmission electron microscopy, CASA, Actl9 knock-in mouse model, immunostaining\",\n      \"journal\": \"Journal of assisted reproduction and genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO/KI animal model with ultrastructural validation, single lab\",\n      \"pmids\": [\"38963606\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ACTL9 localizes to the subacrosomal perinuclear theca region of spermatids, and loss-of-function variants in ACTL9 result in fertilization failure after ICSI, consistent with a role in the acrosomal complex required for sperm-egg fusion.\",\n      \"method\": \"Immunostaining of patient sperm, whole-exome sequencing with segregation analysis, ICSI outcome data\",\n      \"journal\": \"Molecular genetics & genomic medicine\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — single patient variant with in silico and localization data, no direct functional rescue\",\n      \"pmids\": [\"38769899\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ACTL9 is a sperm-specific actin-related protein that forms a multimeric complex with ACTRT1, ACTRT2, and ACTL7A in the subacrosomal perinuclear theca of spermatids, where it anchors the acrosome to the nucleus, supports proper flagellar axonemal and mitochondrial sheath assembly, and undergoes TSSK3-mediated phosphorylation; loss-of-function mutations cause acrosomal detachment, flagellar ultrastructural defects, and complete fertilization failure.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"ACTL9 is a testis-specific actin-related protein that localizes to the subacrosomal perinuclear theca of spermatids, where it forms a multimeric complex with ACTRT1, ACTRT2, and ACTL7A to anchor the acrosome to the nucleus [PMID:35616329]. ACTL9 also interacts with CABS1, and disruption of this interaction leads to acrosome absence, abnormal PLCζ localization, and total fertilization failure [PMID:40407971]. Beyond acrosomal attachment, ACTL9 is required for proper flagellar axonemal organization and mitochondrial sheath assembly, and homozygous loss-of-function mutations cause asthenoteratozoospermia and fertilization failure in both humans and knock-in mouse models [PMID:38963606]. ACTL9 undergoes TSSK3-mediated phosphorylation in germ cells, indicating post-translational regulation of its function during spermiogenesis [PMID:36306217].\",\n  \"teleology\": [\n    {\n      \"year\": 2022,\n      \"claim\": \"Identifying ACTL9 as part of a subacrosomal multimeric complex with ACTRT1, ACTRT2, and ACTL7A established its primary molecular function: mediating the physical connection between the acrosome and the nucleus in spermatids.\",\n      \"evidence\": \"Co-immunoprecipitation, immunostaining, and genetic knockout mouse model in Development\",\n      \"pmids\": [\"35616329\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Stoichiometry and assembly order of the ACTL9–ACTRT1–ACTRT2–ACTL7A complex are unknown\",\n        \"No structural model of the complex exists\",\n        \"Whether ACTL9 has intrinsic actin-like ATPase or filament-forming activity has not been tested\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Phosphoproteomic analysis of Tssk3-knockout germ cells revealed ACTL9 as a TSSK3 phosphorylation substrate, establishing a post-translational regulatory axis for the subacrosomal complex during spermiogenesis.\",\n      \"evidence\": \"Phosphoproteomics of purified germ cells from Tssk3-KO vs. heterozygous mice\",\n      \"pmids\": [\"36306217\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"The specific phosphorylation site(s) on ACTL9 and their functional consequences have not been determined\",\n        \"Whether TSSK3-mediated phosphorylation modulates ACTL9 complex assembly or stability is untested\",\n        \"No in vitro kinase assay confirming direct phosphorylation\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Discovery that homozygous ACTL9 mutations cause flagellar ultrastructural defects—irregular mitochondrial sheath and abnormal 9+2 axoneme—expanded ACTL9's role beyond acrosomal anchoring to flagellar assembly and sperm motility.\",\n      \"evidence\": \"Whole-exome sequencing, TEM/SEM of patient and knock-in mouse sperm, CASA motility analysis\",\n      \"pmids\": [\"38963606\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether ACTL9 acts directly in flagellar assembly or the defect is secondary to perinuclear theca disruption is unclear\",\n        \"Single-lab study; independent replication in additional cohorts not yet reported\",\n        \"Molecular partners of ACTL9 in the flagellar compartment are unidentified\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identification of CABS1 as an ACTL9-interacting partner, and demonstration that a CABS1 nonsense mutation disrupts this interaction and causes acrosome absence with fertilization failure, linked the ACTL9 interaction network to oocyte activation (via PLCζ mislocalization).\",\n      \"evidence\": \"Co-IP of wild-type vs. mutant CABS1 with ACTL9, immunofluorescence, western blot\",\n      \"pmids\": [\"40407971\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether ACTL9 directly recruits PLCζ or the effect is indirect through CABS1 is unknown\",\n        \"Single study without reciprocal ACTL9 perturbation to confirm directionality\",\n        \"Binding domain mapping between ACTL9 and CABS1 has not been performed\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unknown whether ACTL9 possesses intrinsic actin-like biochemical activities (ATPase, polymerization), how TSSK3 phosphorylation regulates complex dynamics, and whether ACTL9's flagellar role is direct or secondary to perinuclear theca disruption.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No in vitro biochemical characterization of ACTL9\",\n        \"No high-resolution structural data for ACTL9 or its complexes\",\n        \"Causal relationship between ACTL9 loss and flagellar vs. acrosomal defects not dissected\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"complexes\": [\n      \"ACTRT1–ACTRT2–ACTL7A–ACTL9 subacrosomal complex\"\n    ],\n    \"partners\": [\n      \"ACTRT1\",\n      \"ACTRT2\",\n      \"ACTL7A\",\n      \"CABS1\",\n      \"TSSK3\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}