{"gene":"TEKT3","run_date":"2026-04-28T21:42:58","timeline":{"discoveries":[{"year":2004,"finding":"TEKT3 is a microtubule-associated cytoskeletal protein expressed preferentially in late pachytene spermatocytes and early round spermatids in mouse testes, with the encoded protein sharing a conserved carboxy-terminal nonapeptide signature sequence present in all TEKTIN family members, consistent with a role in axonemal architecture and microtubule stability in sperm flagella.","method":"RT-PCR, Northern blot, in situ hybridization, bioinformatic sequence analysis","journal":"Molecular reproduction and development","confidence":"Medium","confidence_rationale":"Tier 3 — localization established by in situ hybridization and sequence analysis in a single study; no functional rescue or in vitro assay","pmids":["14735490"],"is_preprint":false},{"year":2009,"finding":"TEKT3 is required for progressive sperm motility and normal flagellar architecture in mice; male mice null for TEKT3 show reduced sperm motility (47.2%) and increased flagellar structural bending defects, and double knockout of TEKT3 and TEKT4 causes subfertility, indicating partially non-redundant roles.","method":"Knockout mouse generation, sperm motility analysis, flagellar ultrastructure analysis, fertility testing","journal":"Molecular reproduction and development","confidence":"High","confidence_rationale":"Tier 2 — clean KO with defined cellular phenotype (motility, morphology), double-KO genetic epistasis confirming non-redundancy","pmids":["18951373"],"is_preprint":false},{"year":2015,"finding":"TEKT3 was identified as a component of the outer acrosomal membrane-associated matrix (OMC45 polypeptide) in bovine sperm heads, localizing to the acrosomal segment as shown by immunofluorescence and confirmed by MALDI-TOF-TOF proteomics and immunoprecipitation.","method":"MALDI-TOF-TOF proteomics, immunoprecipitation, immunofluorescence","journal":"Molecular and cellular biochemistry","confidence":"Medium","confidence_rationale":"Tier 3 — single lab, proteomic identification plus immunoprecipitation and immunofluorescence confirming acrosomal localization","pmids":["26268136"],"is_preprint":false},{"year":2016,"finding":"In bull spermatozoa, TEKT3 resides beneath the plasma membrane of the post-acrosomal region in unactivated sperm and translocates to the equatorial segment upon hyperactivation induced by dibutyryl cAMP and the protein phosphatase inhibitor calyculin A; TEKT3 is subsequently lost from the equatorial segment during the acrosome reaction.","method":"Immunofluorescence localization, pharmacological hyperactivation (dibutyryl cAMP + calyculin A), acrosome reaction assay","journal":"Molecular reproduction and development","confidence":"Medium","confidence_rationale":"Tier 2 — direct localization experiment linked to capacitation/hyperactivation functional state; single lab but multiple conditions tested","pmids":["27883267"],"is_preprint":false},{"year":2023,"finding":"Bi-allelic loss-of-function mutations in human TEKT3 (homozygous deletion-insertion causing p.Glu182* and compound heterozygous p.[Arg183Gln];[Gln251Pro]) cause oligoasthenoteratozoospermia with reduced progressive sperm motility and acrosomal hypoplasia; TEKT3 was shown by co-immunoprecipitation to bind other TEKTIN family proteins, suggesting it forms a complex within human spermatozoa.","method":"Whole-exome sequencing, Sanger sequencing, Western blot, immunofluorescence, co-immunoprecipitation, sperm functional analysis, ICSI","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 — human genetics with functional validation (protein expression loss, motility, morphology defects), plus Co-IP establishing TEKTIN complex formation; multiple orthogonal methods","pmids":["36708031"],"is_preprint":false},{"year":2023,"finding":"Knockout of Ccdc38 causes decreased levels of TEKT3 in testes and aberrant distribution of TEKT3 in sperm, placing TEKT3 downstream of CCDC38 in acrosome biogenesis; TEKT3 mislocalization is associated with acrosomal hypoplasia in MMAF sperm.","method":"Base-editing KO mouse generation, Western blot, immunofluorescence, sperm phenotype analysis","journal":"Journal of genetics and genomics","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis by KO showing TEKT3 protein level and localization depend on CCDC38; single lab","pmids":["37709195"],"is_preprint":false},{"year":2024,"finding":"TEKTIP1 predominantly interacts with TEKT3 among tektin family members; loss of TEKTIP1 disrupts the tektin bundle mainly by affecting the native status of TEKT3 and its interaction with other tektins, leading to disorganized axoneme structures and reduced sperm motility in mice.","method":"Knockout mouse generation (Tektip1-/-), co-immunoprecipitation, cryo-EM-based localization, sperm motility and ultrastructure analysis","journal":"Cellular and molecular life sciences","confidence":"High","confidence_rationale":"Tier 1–2 — cryo-EM localization, reciprocal interaction (Co-IP of TEKTIP1 with TEKT3), KO phenotype showing TEKT3-dependent tektin bundle disruption; multiple orthogonal methods","pmids":["38448737"],"is_preprint":false},{"year":2025,"finding":"In zebrafish, tekt3 is expressed in inner ear and lateral line neuromast hair cells; Tekt3 protein localizes to the apical cytosol of neuromast and utricular hair cells (enriched in non-hearing hair cell subtypes), and tekt3 mutants display kinocilia morphological defects in neuromast hair cells, resulting in reduced vital dye intake, delayed hair cell regeneration after neomycin treatment, and reduced startle response; these phenotypes are rescued by wild-type tekt3 mRNA.","method":"Antibody staining/immunofluorescence, tekt3 mutant zebrafish, mRNA rescue, vital dye uptake assay, behavioral (startle response) assay","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 — localization with functional consequence in KO, mRNA rescue confirming specificity; single lab, zebrafish ortholog","pmids":["40243732"],"is_preprint":false},{"year":2025,"finding":"Individual CRISPR/Cas9-mediated knockout of Tekt3 in mice results in no significant defect in male fertility, testis morphology, or sperm motility parameters, suggesting Tekt3 alone is dispensable for male fecundity in mice under standard conditions.","method":"CRISPR/Cas9 knockout, mating tests, sperm motility parameter analysis, testis/epididymis histology","journal":"Journal of biomedical research","confidence":"Medium","confidence_rationale":"Tier 2 — clean KO with defined phenotypic readouts; contrasts with earlier Tekt3-KO study (18951373) but uses C57BL/6 background; single lab","pmids":["41194443"],"is_preprint":false}],"current_model":"TEKT3 is an evolutionarily conserved tektin filamentous protein that localizes to the axoneme and acrosomal structures of sperm, where it forms a complex with other TEKTIN family members (stabilized by TEKTIP1) to maintain doublet microtubule integrity and axonemal architecture; loss of TEKT3 function in humans causes oligoasthenoteratozoospermia with reduced progressive sperm motility and acrosomal hypoplasia, while in mouse models it contributes to progressive sperm motility in a partially non-redundant manner with TEKT4, and in zebrafish it maintains kinocilia integrity in neuromast hair cells."},"narrative":{"teleology":[{"year":2004,"claim":"Initial cloning established TEKT3 as a testis-enriched tektin family member expressed in late spermatocytes and early spermatids, placing it temporally in the window of flagellar biogenesis.","evidence":"RT-PCR, Northern blot, and in situ hybridization in mouse testes","pmids":["14735490"],"confidence":"Medium","gaps":["No functional data or loss-of-function phenotype at this stage","Protein-level localization within flagellar substructures not determined","No information on whether TEKT3 acts redundantly with other tektins"]},{"year":2009,"claim":"Knockout studies demonstrated that TEKT3 is required for normal progressive sperm motility and flagellar architecture, and double-KO with TEKT4 revealed partial non-redundancy by causing subfertility beyond single-KO effects.","evidence":"Tekt3-null and Tekt3/Tekt4 double-null mice, sperm motility and ultrastructure analysis, fertility testing","pmids":["18951373"],"confidence":"High","gaps":["Molecular mechanism of motility defect (dynein arm integrity, axonemal periodicity) not resolved","Whether TEKT3 interacts directly with TEKT4 or they stabilize the axoneme independently was unknown"]},{"year":2015,"claim":"Proteomic identification of TEKT3 in the outer acrosomal membrane matrix expanded its known localization beyond the flagellum to the sperm head acrosomal compartment.","evidence":"MALDI-TOF-TOF proteomics, immunoprecipitation, and immunofluorescence in bovine sperm","pmids":["26268136"],"confidence":"Medium","gaps":["Single species (bovine); conservation of acrosomal localization in human sperm not shown","Functional significance of acrosomal TEKT3 not tested"]},{"year":2016,"claim":"Dynamic redistribution of TEKT3 from the post-acrosomal region to the equatorial segment during hyperactivation, and its loss during the acrosome reaction, linked TEKT3 to capacitation-associated membrane/cytoskeletal remodeling.","evidence":"Immunofluorescence in bull sperm under pharmacological hyperactivation and acrosome reaction conditions","pmids":["27883267"],"confidence":"Medium","gaps":["Mechanism of TEKT3 translocation (phosphorylation, scaffolding) not identified","Functional consequence of preventing TEKT3 redistribution not tested"]},{"year":2023,"claim":"Human genetic evidence established bi-allelic TEKT3 mutations as a cause of oligoasthenoteratozoospermia with acrosomal hypoplasia, and co-immunoprecipitation demonstrated TEKT3 forms a complex with other TEKTIN family proteins in human sperm.","evidence":"Whole-exome sequencing of infertile men, Sanger validation, Western blot, immunofluorescence, co-IP in human spermatozoa","pmids":["36708031"],"confidence":"High","gaps":["Stoichiometry and architecture of the human TEKTIN complex not resolved","No structural data for TEKT3 or its disease-associated variants"]},{"year":2023,"claim":"Epistasis experiments placed TEKT3 downstream of CCDC38 in acrosome biogenesis, showing that CCDC38 is required for TEKT3 protein levels and proper acrosomal localization.","evidence":"Ccdc38-knockout mice (base editing), Western blot and immunofluorescence of TEKT3 in sperm","pmids":["37709195"],"confidence":"Medium","gaps":["Whether CCDC38 directly binds TEKT3 or acts indirectly is unknown","Single lab; no reciprocal rescue by TEKT3 overexpression tested"]},{"year":2024,"claim":"Identification of TEKTIP1 as the primary stabilizer of TEKT3 within the tektin bundle clarified the molecular basis of axonemal tektin filament assembly: TEKTIP1 loss preferentially destabilizes TEKT3 and disrupts its interactions with other tektins.","evidence":"Tektip1-knockout mice, co-immunoprecipitation, cryo-EM-based localization, sperm motility and ultrastructure analysis","pmids":["38448737"],"confidence":"High","gaps":["Atomic-resolution structure of the TEKTIP1–TEKT3 interface not determined","Whether TEKTIP1 acts as a chaperone during assembly or a structural brace in the mature filament is unresolved"]},{"year":2025,"claim":"Extension to a non-reproductive context showed that TEKT3 maintains kinocilia integrity in zebrafish neuromast hair cells, with mutants displaying morphological defects, impaired mechanosensory function, and delayed hair cell regeneration — all rescued by wild-type mRNA.","evidence":"tekt3-mutant zebrafish, immunofluorescence, vital dye uptake, startle response assay, mRNA rescue","pmids":["40243732"],"confidence":"Medium","gaps":["Whether mammalian TEKT3 has analogous ciliary roles outside the germline is untested","Molecular basis of kinocilia structural defect not characterized at the ultrastructural level"]},{"year":2025,"claim":"A second Tekt3-KO mouse study found no significant fertility or motility defect, revealing strain- or condition-dependent penetrance of the loss-of-function phenotype and complicating the simple model of TEKT3 essentiality in mouse spermatogenesis.","evidence":"CRISPR/Cas9 knockout on C57BL/6 background, mating tests, sperm motility, histology","pmids":["41194443"],"confidence":"Medium","gaps":["Discrepancy with earlier KO (PMID:18951373) not resolved — genetic background, housing conditions, or assay sensitivity differences not systematically tested","Whether compensatory upregulation of other tektins occurs in C57BL/6 background is unknown"]},{"year":null,"claim":"Key unresolved questions include the atomic structure of the TEKT3-containing tektin filament, the precise mechanism by which TEKT3 contributes to acrosome biogenesis versus axonemal integrity, and why TEKT3 loss in mice shows variable penetrance across genetic backgrounds.","evidence":"","pmids":[],"confidence":"Low","gaps":["No high-resolution structure of TEKT3 or the tektin bundle","Mechanism of TEKT3 involvement in acrosome formation remains indirect (downstream of CCDC38)","Reconciliation of contrasting mouse KO phenotypes requires systematic background-controlled studies"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0,1,6]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[0,1,6]},{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[1,7]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[7]}],"pathway":[{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[1,6,7]}],"complexes":["Tektin filament bundle"],"partners":["TEKTIP1","TEKT4","CCDC38"],"other_free_text":[]},"mechanistic_narrative":"TEKT3 is a tektin family filamentous protein that functions in axonemal and acrosomal architecture of spermatozoa and in kinocilia maintenance of sensory hair cells. In sperm, TEKT3 assembles with other TEKTIN family members into a bundle stabilized by TEKTIP1; loss of TEKTIP1 primarily disrupts TEKT3 and its interactions with other tektins, leading to disorganized axoneme structures and reduced motility [PMID:38448737]. TEKT3 also localizes to acrosomal structures and depends on CCDC38 for proper acrosomal targeting, with its mislocalization associated with acrosomal hypoplasia [PMID:26268136, PMID:37709195]. Bi-allelic loss-of-function mutations in human TEKT3 cause oligoasthenoteratozoospermia with reduced progressive sperm motility and acrosomal hypoplasia [PMID:36708031]."},"prefetch_data":{"uniprot":{"accession":"Q9BXF9","full_name":"Tektin-3","aliases":[],"length_aa":490,"mass_kda":56.6,"function":"Microtubule inner protein (MIP) part of the dynein-decorated doublet microtubules (DMTs) in cilia and flagellar axoneme (PubMed:36191189). Forms filamentous polymers in the walls of ciliary and flagellar microtubules (By similarity). Required for normal sperm mobility (By similarity)","subcellular_location":"Cytoplasm, cytoskeleton, cilium axoneme; Cytoplasm, cytoskeleton, flagellum axoneme; Cytoplasmic vesicle, secretory vesicle, acrosome outer membrane","url":"https://www.uniprot.org/uniprotkb/Q9BXF9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TEKT3","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/TEKT3","total_profiled":1310},"omim":[{"mim_id":"620277","title":"SPERMATOGENIC FAILURE 81; SPGF81","url":"https://www.omim.org/entry/620277"},{"mim_id":"618686","title":"TEKTIN 5; TEKT5","url":"https://www.omim.org/entry/618686"},{"mim_id":"612683","title":"TEKTIN 3; TEKT3","url":"https://www.omim.org/entry/612683"},{"mim_id":"601097","title":"PERIPHERAL MYELIN PROTEIN 22; PMP22","url":"https://www.omim.org/entry/601097"},{"mim_id":"258150","title":"SPERMATOGENIC FAILURE 1; SPGF1","url":"https://www.omim.org/entry/258150"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Mid piece","reliability":"Supported"},{"location":"Principal piece","reliability":"Supported"},{"location":"End piece","reliability":"Supported"},{"location":"Equatorial segment","reliability":"Additional"},{"location":"Calyx","reliability":"Additional"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"testis","ntpm":29.9}],"url":"https://www.proteinatlas.org/search/TEKT3"},"hgnc":{"alias_symbol":["FLJ32828"],"prev_symbol":[]},"alphafold":{"accession":"Q9BXF9","domains":[{"cath_id":"1.10.287","chopping":"359-488","consensus_level":"medium","plddt":95.7568,"start":359,"end":488}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BXF9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BXF9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BXF9-F1-predicted_aligned_error_v6.png","plddt_mean":85.88},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TEKT3","jax_strain_url":"https://www.jax.org/strain/search?query=TEKT3"},"sequence":{"accession":"Q9BXF9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9BXF9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9BXF9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BXF9"}},"corpus_meta":[{"pmid":"11381029","id":"PMC_11381029","title":"The 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putative testicular microtubules-related protein expressed preferentially in male germ cells.","date":"2004","source":"Molecular reproduction and development","url":"https://pubmed.ncbi.nlm.nih.gov/14735490","citation_count":46,"is_preprint":false},{"pmid":"25999357","id":"PMC_25999357","title":"Spermatozoa protein alterations in infertile men with bilateral varicocele.","date":"2016","source":"Asian journal of andrology","url":"https://pubmed.ncbi.nlm.nih.gov/25999357","citation_count":36,"is_preprint":false},{"pmid":"36766254","id":"PMC_36766254","title":"Identification of New Candidate Genes Related to Semen Traits in Duroc Pigs through Weighted Single-Step GWAS.","date":"2023","source":"Animals : an open access journal from MDPI","url":"https://pubmed.ncbi.nlm.nih.gov/36766254","citation_count":18,"is_preprint":false},{"pmid":"32251302","id":"PMC_32251302","title":"Transcriptomic analysis of female and male gonads in juvenile snakeskin gourami (Trichopodus 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CMLS","url":"https://pubmed.ncbi.nlm.nih.gov/38448737","citation_count":10,"is_preprint":false},{"pmid":"26268136","id":"PMC_26268136","title":"Identification and characterization of a bovine sperm acrosomal matrix protein and its mechanism of interaction with acrosomal hydrolases.","date":"2015","source":"Molecular and cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/26268136","citation_count":8,"is_preprint":false},{"pmid":"37709195","id":"PMC_37709195","title":"Coiled-coil domain-containing 38 is required for acrosome biogenesis and fibrous sheath assembly in mice.","date":"2023","source":"Journal of genetics and genomics = Yi chuan xue bao","url":"https://pubmed.ncbi.nlm.nih.gov/37709195","citation_count":6,"is_preprint":false},{"pmid":"35804605","id":"PMC_35804605","title":"Comparative Proteomic Analyses of Poorly Motile Swamp Buffalo Spermatozoa Reveal Low Energy Metabolism and Deficiencies in Motility-Related Proteins.","date":"2022","source":"Animals : an open 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spermatids in mouse testes, with the encoded protein sharing a conserved carboxy-terminal nonapeptide signature sequence present in all TEKTIN family members, consistent with a role in axonemal architecture and microtubule stability in sperm flagella.\",\n      \"method\": \"RT-PCR, Northern blot, in situ hybridization, bioinformatic sequence analysis\",\n      \"journal\": \"Molecular reproduction and development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — localization established by in situ hybridization and sequence analysis in a single study; no functional rescue or in vitro assay\",\n      \"pmids\": [\"14735490\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"TEKT3 is required for progressive sperm motility and normal flagellar architecture in mice; male mice null for TEKT3 show reduced sperm motility (47.2%) and increased flagellar structural bending defects, and double knockout of TEKT3 and TEKT4 causes subfertility, indicating partially non-redundant roles.\",\n      \"method\": \"Knockout mouse generation, sperm motility analysis, flagellar ultrastructure analysis, fertility testing\",\n      \"journal\": \"Molecular reproduction and development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined cellular phenotype (motility, morphology), double-KO genetic epistasis confirming non-redundancy\",\n      \"pmids\": [\"18951373\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"TEKT3 was identified as a component of the outer acrosomal membrane-associated matrix (OMC45 polypeptide) in bovine sperm heads, localizing to the acrosomal segment as shown by immunofluorescence and confirmed by MALDI-TOF-TOF proteomics and immunoprecipitation.\",\n      \"method\": \"MALDI-TOF-TOF proteomics, immunoprecipitation, immunofluorescence\",\n      \"journal\": \"Molecular and cellular biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single lab, proteomic identification plus immunoprecipitation and immunofluorescence confirming acrosomal localization\",\n      \"pmids\": [\"26268136\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"In bull spermatozoa, TEKT3 resides beneath the plasma membrane of the post-acrosomal region in unactivated sperm and translocates to the equatorial segment upon hyperactivation induced by dibutyryl cAMP and the protein phosphatase inhibitor calyculin A; TEKT3 is subsequently lost from the equatorial segment during the acrosome reaction.\",\n      \"method\": \"Immunofluorescence localization, pharmacological hyperactivation (dibutyryl cAMP + calyculin A), acrosome reaction assay\",\n      \"journal\": \"Molecular reproduction and development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct localization experiment linked to capacitation/hyperactivation functional state; single lab but multiple conditions tested\",\n      \"pmids\": [\"27883267\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Bi-allelic loss-of-function mutations in human TEKT3 (homozygous deletion-insertion causing p.Glu182* and compound heterozygous p.[Arg183Gln];[Gln251Pro]) cause oligoasthenoteratozoospermia with reduced progressive sperm motility and acrosomal hypoplasia; TEKT3 was shown by co-immunoprecipitation to bind other TEKTIN family proteins, suggesting it forms a complex within human spermatozoa.\",\n      \"method\": \"Whole-exome sequencing, Sanger sequencing, Western blot, immunofluorescence, co-immunoprecipitation, sperm functional analysis, ICSI\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — human genetics with functional validation (protein expression loss, motility, morphology defects), plus Co-IP establishing TEKTIN complex formation; multiple orthogonal methods\",\n      \"pmids\": [\"36708031\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Knockout of Ccdc38 causes decreased levels of TEKT3 in testes and aberrant distribution of TEKT3 in sperm, placing TEKT3 downstream of CCDC38 in acrosome biogenesis; TEKT3 mislocalization is associated with acrosomal hypoplasia in MMAF sperm.\",\n      \"method\": \"Base-editing KO mouse generation, Western blot, immunofluorescence, sperm phenotype analysis\",\n      \"journal\": \"Journal of genetics and genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis by KO showing TEKT3 protein level and localization depend on CCDC38; single lab\",\n      \"pmids\": [\"37709195\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TEKTIP1 predominantly interacts with TEKT3 among tektin family members; loss of TEKTIP1 disrupts the tektin bundle mainly by affecting the native status of TEKT3 and its interaction with other tektins, leading to disorganized axoneme structures and reduced sperm motility in mice.\",\n      \"method\": \"Knockout mouse generation (Tektip1-/-), co-immunoprecipitation, cryo-EM-based localization, sperm motility and ultrastructure analysis\",\n      \"journal\": \"Cellular and molecular life sciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — cryo-EM localization, reciprocal interaction (Co-IP of TEKTIP1 with TEKT3), KO phenotype showing TEKT3-dependent tektin bundle disruption; multiple orthogonal methods\",\n      \"pmids\": [\"38448737\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In zebrafish, tekt3 is expressed in inner ear and lateral line neuromast hair cells; Tekt3 protein localizes to the apical cytosol of neuromast and utricular hair cells (enriched in non-hearing hair cell subtypes), and tekt3 mutants display kinocilia morphological defects in neuromast hair cells, resulting in reduced vital dye intake, delayed hair cell regeneration after neomycin treatment, and reduced startle response; these phenotypes are rescued by wild-type tekt3 mRNA.\",\n      \"method\": \"Antibody staining/immunofluorescence, tekt3 mutant zebrafish, mRNA rescue, vital dye uptake assay, behavioral (startle response) assay\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — localization with functional consequence in KO, mRNA rescue confirming specificity; single lab, zebrafish ortholog\",\n      \"pmids\": [\"40243732\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Individual CRISPR/Cas9-mediated knockout of Tekt3 in mice results in no significant defect in male fertility, testis morphology, or sperm motility parameters, suggesting Tekt3 alone is dispensable for male fecundity in mice under standard conditions.\",\n      \"method\": \"CRISPR/Cas9 knockout, mating tests, sperm motility parameter analysis, testis/epididymis histology\",\n      \"journal\": \"Journal of biomedical research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined phenotypic readouts; contrasts with earlier Tekt3-KO study (18951373) but uses C57BL/6 background; single lab\",\n      \"pmids\": [\"41194443\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TEKT3 is an evolutionarily conserved tektin filamentous protein that localizes to the axoneme and acrosomal structures of sperm, where it forms a complex with other TEKTIN family members (stabilized by TEKTIP1) to maintain doublet microtubule integrity and axonemal architecture; loss of TEKT3 function in humans causes oligoasthenoteratozoospermia with reduced progressive sperm motility and acrosomal hypoplasia, while in mouse models it contributes to progressive sperm motility in a partially non-redundant manner with TEKT4, and in zebrafish it maintains kinocilia integrity in neuromast hair cells.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"TEKT3 is a tektin family filamentous protein that functions in axonemal and acrosomal architecture of spermatozoa and in kinocilia maintenance of sensory hair cells. In sperm, TEKT3 assembles with other TEKTIN family members into a bundle stabilized by TEKTIP1; loss of TEKTIP1 primarily disrupts TEKT3 and its interactions with other tektins, leading to disorganized axoneme structures and reduced motility [PMID:38448737]. TEKT3 also localizes to acrosomal structures and depends on CCDC38 for proper acrosomal targeting, with its mislocalization associated with acrosomal hypoplasia [PMID:26268136, PMID:37709195]. Bi-allelic loss-of-function mutations in human TEKT3 cause oligoasthenoteratozoospermia with reduced progressive sperm motility and acrosomal hypoplasia [PMID:36708031].\",\n  \"teleology\": [\n    {\n      \"year\": 2004,\n      \"claim\": \"Initial cloning established TEKT3 as a testis-enriched tektin family member expressed in late spermatocytes and early spermatids, placing it temporally in the window of flagellar biogenesis.\",\n      \"evidence\": \"RT-PCR, Northern blot, and in situ hybridization in mouse testes\",\n      \"pmids\": [\"14735490\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No functional data or loss-of-function phenotype at this stage\",\n        \"Protein-level localization within flagellar substructures not determined\",\n        \"No information on whether TEKT3 acts redundantly with other tektins\"\n      ]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Knockout studies demonstrated that TEKT3 is required for normal progressive sperm motility and flagellar architecture, and double-KO with TEKT4 revealed partial non-redundancy by causing subfertility beyond single-KO effects.\",\n      \"evidence\": \"Tekt3-null and Tekt3/Tekt4 double-null mice, sperm motility and ultrastructure analysis, fertility testing\",\n      \"pmids\": [\"18951373\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Molecular mechanism of motility defect (dynein arm integrity, axonemal periodicity) not resolved\",\n        \"Whether TEKT3 interacts directly with TEKT4 or they stabilize the axoneme independently was unknown\"\n      ]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Proteomic identification of TEKT3 in the outer acrosomal membrane matrix expanded its known localization beyond the flagellum to the sperm head acrosomal compartment.\",\n      \"evidence\": \"MALDI-TOF-TOF proteomics, immunoprecipitation, and immunofluorescence in bovine sperm\",\n      \"pmids\": [\"26268136\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single species (bovine); conservation of acrosomal localization in human sperm not shown\",\n        \"Functional significance of acrosomal TEKT3 not tested\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Dynamic redistribution of TEKT3 from the post-acrosomal region to the equatorial segment during hyperactivation, and its loss during the acrosome reaction, linked TEKT3 to capacitation-associated membrane/cytoskeletal remodeling.\",\n      \"evidence\": \"Immunofluorescence in bull sperm under pharmacological hyperactivation and acrosome reaction conditions\",\n      \"pmids\": [\"27883267\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism of TEKT3 translocation (phosphorylation, scaffolding) not identified\",\n        \"Functional consequence of preventing TEKT3 redistribution not tested\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Human genetic evidence established bi-allelic TEKT3 mutations as a cause of oligoasthenoteratozoospermia with acrosomal hypoplasia, and co-immunoprecipitation demonstrated TEKT3 forms a complex with other TEKTIN family proteins in human sperm.\",\n      \"evidence\": \"Whole-exome sequencing of infertile men, Sanger validation, Western blot, immunofluorescence, co-IP in human spermatozoa\",\n      \"pmids\": [\"36708031\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Stoichiometry and architecture of the human TEKTIN complex not resolved\",\n        \"No structural data for TEKT3 or its disease-associated variants\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Epistasis experiments placed TEKT3 downstream of CCDC38 in acrosome biogenesis, showing that CCDC38 is required for TEKT3 protein levels and proper acrosomal localization.\",\n      \"evidence\": \"Ccdc38-knockout mice (base editing), Western blot and immunofluorescence of TEKT3 in sperm\",\n      \"pmids\": [\"37709195\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether CCDC38 directly binds TEKT3 or acts indirectly is unknown\",\n        \"Single lab; no reciprocal rescue by TEKT3 overexpression tested\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identification of TEKTIP1 as the primary stabilizer of TEKT3 within the tektin bundle clarified the molecular basis of axonemal tektin filament assembly: TEKTIP1 loss preferentially destabilizes TEKT3 and disrupts its interactions with other tektins.\",\n      \"evidence\": \"Tektip1-knockout mice, co-immunoprecipitation, cryo-EM-based localization, sperm motility and ultrastructure analysis\",\n      \"pmids\": [\"38448737\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Atomic-resolution structure of the TEKTIP1–TEKT3 interface not determined\",\n        \"Whether TEKTIP1 acts as a chaperone during assembly or a structural brace in the mature filament is unresolved\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Extension to a non-reproductive context showed that TEKT3 maintains kinocilia integrity in zebrafish neuromast hair cells, with mutants displaying morphological defects, impaired mechanosensory function, and delayed hair cell regeneration — all rescued by wild-type mRNA.\",\n      \"evidence\": \"tekt3-mutant zebrafish, immunofluorescence, vital dye uptake, startle response assay, mRNA rescue\",\n      \"pmids\": [\"40243732\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether mammalian TEKT3 has analogous ciliary roles outside the germline is untested\",\n        \"Molecular basis of kinocilia structural defect not characterized at the ultrastructural level\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"A second Tekt3-KO mouse study found no significant fertility or motility defect, revealing strain- or condition-dependent penetrance of the loss-of-function phenotype and complicating the simple model of TEKT3 essentiality in mouse spermatogenesis.\",\n      \"evidence\": \"CRISPR/Cas9 knockout on C57BL/6 background, mating tests, sperm motility, histology\",\n      \"pmids\": [\"41194443\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Discrepancy with earlier KO (PMID:18951373) not resolved — genetic background, housing conditions, or assay sensitivity differences not systematically tested\",\n        \"Whether compensatory upregulation of other tektins occurs in C57BL/6 background is unknown\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the atomic structure of the TEKT3-containing tektin filament, the precise mechanism by which TEKT3 contributes to acrosome biogenesis versus axonemal integrity, and why TEKT3 loss in mice shows variable penetrance across genetic backgrounds.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No high-resolution structure of TEKT3 or the tektin bundle\",\n        \"Mechanism of TEKT3 involvement in acrosome formation remains indirect (downstream of CCDC38)\",\n        \"Reconciliation of contrasting mouse KO phenotypes requires systematic background-controlled studies\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0, 1, 6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [0, 1, 6]},\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [1, 7]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [7]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [1, 6, 7]}\n    ],\n    \"complexes\": [\n      \"Tektin filament bundle\"\n    ],\n    \"partners\": [\n      \"TEKTIP1\",\n      \"TEKT4\",\n      \"CCDC38\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}