{"gene":"DRC5","run_date":"2026-06-09T23:54:42","timeline":{"discoveries":[{"year":2017,"finding":"TCTE1 (DRC5) is a conserved component of the nexin-dynein regulatory complex (N-DRC) of the axoneme, localized to the flagellum of mouse spermatozoa. Knockout of Tcte1 causes male sterility with aberrant sperm motility despite structurally normal axonemes, and Tcte1-null sperm show a significant decrease in ATP levels, linking TCTE1 to energy metabolism required for dynein motor function.","method":"Mouse knockout (Tcte1-null), immunofluorescence localization, ATP measurement, transmission electron microscopy, Northern/Western blot","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO with defined cellular phenotype, protein localization to flagellum, ATP measurement as functional readout, axoneme structural analysis; single lab but multiple orthogonal methods","pmids":["28630322"],"is_preprint":false},{"year":2020,"finding":"TCTE1 (DRC5) interacts with FBXL13 (DRC6) and DRC7 within the N-DRC complex in the mammalian sperm flagellum. DRC7 (but not FBXL13) is required for correct assembly of the N-DRC and for incorporating other N-DRC components, including TCTE1, into the flagellum.","method":"Mouse knockout of Drc7 and Fbxl13, immunofluorescence, electron microscopy of axoneme structure, Western blot for N-DRC component localization","journal":"PLoS genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO with defined phenotype and demonstrated loss of N-DRC component incorporation; interaction of TCTE1 with DRC6/DRC7 reported but not independently replicated","pmids":["31961863"],"is_preprint":false},{"year":2022,"finding":"Bi-allelic loss-of-function frameshift variants in human TCTE1/DRC5 cause asthenospermia and male infertility, with structurally normal but low-motility sperm, confirming the conserved requirement of TCTE1 for flagellar motility in humans.","method":"Whole-exome sequencing of infertile patient, protein degradation assay (Western blot showing rapid degradation of mutant TCTE1), clinical semen analysis, IVF rescue experiment","journal":"European journal of human genetics : EJHG","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — human genetic case with protein-level validation (degradation shown by Western blot), single case but consistent with mouse KO findings","pmids":["35388187"],"is_preprint":false},{"year":2024,"finding":"In Tcte1 knockout mice, Tcte1 protein is present only in residual amounts in the sperm head nucleus and is not transported to the sperm flagella; other N-DRC components (DRC7, FBXL13/DRC6, EPS8L1/DRC3) are also absent from the flagella, indicating TCTE1 is required for N-DRC complex assembly and transport to the flagellum. Knockout causes oligoasthenoteratozoospermia with 2.4-fold reduced sperm ATP and disturbed tail:midpiece ratios. Haploinsufficiency causes oligozoospermia. RNA-seq revealed 21 differentially expressed genes related to mitochondrial ATP processing, apoptosis, or spermatogenesis.","method":"CRISPR/Cas9 Tcte1 knockout mice, immunofluorescence localization of N-DRC proteins in sperm, ATP luminescence assay, semen analysis, RNAseq, protein prediction modeling of human variants","journal":"Human reproduction open","confidence":"High","confidence_rationale":"Tier 2 / Moderate — CRISPR KO with multiple orthogonal methods (localization, ATP, RNAseq, electron microscopy of tail morphology), consistent with prior mouse KO study","pmids":["38650655"],"is_preprint":false},{"year":2025,"finding":"DRC5/TCTE1 physically interacts with ANKEF1 (ANKRD5) within the N-DRC of the sperm axoneme. This interaction occurs independently of calcium regulation. ANKEF1 deficiency does not alter ATP levels but causes increased structural heterogeneity of doublet microtubules, suggesting TCTE1 participates in N-DRC-mediated mechanical buffering between adjacent doublet microtubules.","method":"Co-immunoprecipitation of ANKEF1 with DRC5/TCTE1 and DRC4/GAS8, Ankef1 knockout mice, cryo-electron tomography of sperm axoneme, ATP/ROS/mitochondrial membrane potential measurements","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP interaction with DRC5/TCTE1 in the context of the N-DRC, supported by cryo-ET structural data; single lab, peer-reviewed","pmids":["41460250"],"is_preprint":false},{"year":1998,"finding":"The N-terminal domain of TCTE1 shows species-specific sequence divergence correlated with heterospecific sperm-egg binding ability, suggesting the TCTE1 sperm polypeptide contributes to species-specific sperm function; the protein is expressed in early stages of spermatogenesis and is absolutely required for fertilization in mouse.","method":"Comparative amino acid sequence analysis of TCTE1 N-terminal regions across rodent species; heterospecific sperm-egg binding assay","journal":"Journal of andrology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — species comparison and binding assay; no direct mechanistic experiment on the protein's molecular function","pmids":["9570741"],"is_preprint":false}],"current_model":"TCTE1/DRC5 is an evolutionarily conserved axonemal protein that forms a structural component of the nexin-dynein regulatory complex (N-DRC) in the sperm flagellum; it is required for N-DRC assembly and transport to the flagellum, for normal sperm ATP production, and for flagellar beating, with loss-of-function causing asthenospermia and male infertility in both mice and humans. TCTE1 physically interacts with DRC6 (FBXL13), DRC7, and ANKEF1 within the N-DRC, contributing to mechanical stability of adjacent doublet microtubules."},"narrative":{"mechanistic_narrative":"TCTE1/DRC5 is an evolutionarily conserved axonemal protein that functions as a structural component of the nexin-dynein regulatory complex (N-DRC) in the sperm flagellum, where it is required for flagellar motility and male fertility [PMID:28630322]. TCTE1 is required for assembly of the N-DRC and its transport to the flagellum: in its absence the protein is retained only in residual amounts in the sperm head nucleus and other N-DRC subunits (DRC7, FBXL13/DRC6, EPS8L1/DRC3) fail to reach the flagellum [PMID:38650655]. Within the complex, TCTE1 physically interacts with FBXL13 (DRC6) and DRC7, with DRC7 being required to incorporate TCTE1 and other components into the flagellum [PMID:31961863], and it also associates with ANKEF1 in a calcium-independent manner, contributing to N-DRC-mediated mechanical buffering between adjacent doublet microtubules [PMID:41460250]. Loss of TCTE1 produces aberrant sperm motility with reduced sperm ATP levels despite structurally normal axonemes, linking the protein to the energy supply required for dynein motor function [PMID:28630322, PMID:38650655]. Bi-allelic loss-of-function variants in human TCTE1 cause asthenospermia and male infertility, establishing a conserved requirement for flagellar motility [PMID:35388187].","teleology":[{"year":2017,"claim":"Established TCTE1/DRC5 as a flagellar N-DRC component whose loss causes male sterility, answering whether the protein has a functional role in sperm motility and energy metabolism.","evidence":"Tcte1-null mouse knockout with flagellar immunofluorescence, ATP measurement, and axoneme electron microscopy","pmids":["28630322"],"confidence":"High","gaps":["Mechanism linking TCTE1 loss to reduced ATP not defined","Direct binding partners within the N-DRC not yet identified","Whether axoneme is biochemically as well as structurally intact unresolved"]},{"year":2020,"claim":"Defined TCTE1's molecular partners and assembly hierarchy, showing it interacts with FBXL13 and DRC7 and that DRC7 is required to incorporate TCTE1 into the flagellum.","evidence":"Drc7 and Fbxl13 knockout mice with immunofluorescence and Western blot for N-DRC component localization","pmids":["31961863"],"confidence":"Medium","gaps":["TCTE1-DRC6/DRC7 interactions not independently replicated","Direct vs indirect nature of interactions not resolved","Stoichiometry within N-DRC unknown"]},{"year":2022,"claim":"Extended the requirement for TCTE1 to humans, showing bi-allelic loss-of-function variants cause asthenospermia and infertility.","evidence":"Whole-exome sequencing of an infertile patient with protein degradation assay and clinical semen analysis","pmids":["35388187"],"confidence":"Medium","gaps":["Single human case limits genotype-phenotype generalization","No structural analysis of patient sperm axonemes","Mechanism of mutant protein degradation not characterized"]},{"year":2024,"claim":"Demonstrated that TCTE1 is required for N-DRC assembly and transport to the flagellum, with broader effects on sperm morphology, ATP, and gene expression.","evidence":"CRISPR/Cas9 Tcte1 knockout mice with N-DRC protein localization, ATP luminescence assay, semen analysis, and RNA-seq","pmids":["38650655"],"confidence":"High","gaps":["Why residual TCTE1 localizes to the sperm head nucleus unexplained","Causal link between transcriptional changes and phenotype not established","Order of N-DRC subunit recruitment not fully mapped"]},{"year":2025,"claim":"Identified ANKEF1 as a calcium-independent TCTE1 partner and connected the complex to mechanical buffering of doublet microtubules.","evidence":"Co-immunoprecipitation of ANKEF1 with DRC5/TCTE1 and DRC4/GAS8, Ankef1 knockout mice, and cryo-electron tomography","pmids":["41460250"],"confidence":"Medium","gaps":["Co-IP not reciprocally validated for direct binding","Functional consequence of TCTE1-ANKEF1 interaction for motility untested","Whether mechanical buffering is mediated by TCTE1 itself unresolved"]},{"year":null,"claim":"How TCTE1 mechanistically couples N-DRC integrity to sperm ATP levels and dynein motor regulation remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of TCTE1 within the assembled N-DRC","Mechanism connecting TCTE1 loss to reduced ATP undefined","Direct biochemical demonstration of TCTE1 binding interfaces lacking"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[0,3,4]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[0,4]}],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[0,2,3]}],"complexes":["nexin-dynein regulatory complex (N-DRC)"],"partners":["FBXL13","DRC7","ANKEF1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q5JU00","full_name":"Dynein regulatory complex subunit 5","aliases":["T-complex-associated testis-expressed protein 1","Tcte-1"],"length_aa":501,"mass_kda":55.6,"function":"Component of the nexin-dynein regulatory complex (N-DRC) a key regulator of ciliary/flagellar motility which maintains the alignment and integrity of the distal axoneme and regulates microtubule sliding in motile axonemes. May play a role in the assembly of N-DRC. May be required for sperm motility","subcellular_location":"Cell projection, cilium, flagellum; Cytoplasm, cytoskeleton, flagellum axoneme","url":"https://www.uniprot.org/uniprotkb/Q5JU00/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"TCTE1","url":"https://depmap.org/portal/gene/TCTE1","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/DRC5","total_profiled":1310},"omim":[{"mim_id":"186975","title":"T COMPLEX-ASSOCIATED TESTIS-EXPRESSED 1; TCTE1","url":"https://www.omim.org/entry/186975"}],"hpa":{"profiled":true,"resolved_as":"TCTE1","reliability":"Approved","locations":[{"location":"Vesicles","reliability":"Approved"},{"location":"Mid piece","reliability":"Approved"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Group enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"brain","ntpm":7.9},{"tissue":"fallopian tube","ntpm":13.6},{"tissue":"testis","ntpm":28.4}],"url":"https://www.proteinatlas.org/search/TCTE1"},"hgnc":{"alias_symbol":["D6S46","MGC33600","FAP155"],"prev_symbol":["TCTE1"]},"alphafold":{"accession":"Q5JU00","domains":[{"cath_id":"-","chopping":"77-143","consensus_level":"medium","plddt":92.7501,"start":77,"end":143},{"cath_id":"-","chopping":"144-200_226-291","consensus_level":"medium","plddt":91.9767,"start":144,"end":291},{"cath_id":"3.80.10.10","chopping":"318-487","consensus_level":"medium","plddt":96.3314,"start":318,"end":487}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q5JU00","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q5JU00-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q5JU00-F1-predicted_aligned_error_v6.png","plddt_mean":82.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=DRC5","jax_strain_url":"https://www.jax.org/strain/search?query=DRC5"},"sequence":{"accession":"Q5JU00","fasta_url":"https://rest.uniprot.org/uniprotkb/Q5JU00.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q5JU00/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q5JU00"}},"corpus_meta":[{"pmid":"2063871","id":"PMC_2063871","title":"The gene for autosomal dominant spinocerebellar ataxia (SCA1) maps telomeric to the HLA complex and is closely linked to the D6S89 locus in three large kindreds.","date":"1991","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/2063871","citation_count":126,"is_preprint":false},{"pmid":"7711736","id":"PMC_7711736","title":"Genetic mapping of cleidocranial dysplasia and evidence of a microdeletion in one family.","date":"1995","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/7711736","citation_count":98,"is_preprint":false},{"pmid":"8352275","id":"PMC_8352275","title":"Linkage analysis of idiopathic generalized epilepsy (IGE) and marker loci on chromosome 6p in families of patients with juvenile myoclonic epilepsy: no evidence for an epilepsy locus in the HLA region.","date":"1993","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/8352275","citation_count":91,"is_preprint":false},{"pmid":"28630322","id":"PMC_28630322","title":"TCTE1 is a conserved component of the dynein regulatory complex and is required for motility and metabolism in mouse spermatozoa.","date":"2017","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/28630322","citation_count":85,"is_preprint":false},{"pmid":"31961863","id":"PMC_31961863","title":"Nexin-Dynein regulatory complex component DRC7 but not FBXL13 is required for sperm flagellum formation and male fertility in mice.","date":"2020","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/31961863","citation_count":40,"is_preprint":false},{"pmid":"1916824","id":"PMC_1916824","title":"Linkage mapping and fluorescence in situ hybridization of TCTE1 on human chromosome 6p: analysis of dinucleotide polymorphisms on native gels.","date":"1991","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/1916824","citation_count":29,"is_preprint":false},{"pmid":"8646886","id":"PMC_8646886","title":"Cloning, expression, and mapping of TCTEL1, a putative human homologue of murine Tcte1, to 6q.","date":"1996","source":"Cytogenetics and cell genetics","url":"https://pubmed.ncbi.nlm.nih.gov/8646886","citation_count":29,"is_preprint":false},{"pmid":"25761592","id":"PMC_25761592","title":"Comparative analysis of testis transcriptomes from triploid and fertile diploid cyprinid fish.","date":"2015","source":"Biology of reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/25761592","citation_count":28,"is_preprint":false},{"pmid":"9647638","id":"PMC_9647638","title":"Physical map of human 6p21.2-6p21.3: region flanking the centromeric end of the major histocompatibility complex.","date":"1998","source":"Genome research","url":"https://pubmed.ncbi.nlm.nih.gov/9647638","citation_count":28,"is_preprint":false},{"pmid":"35388187","id":"PMC_35388187","title":"Bi-allelic variants in human TCTE1/DRC5 cause asthenospermia and male infertility.","date":"2022","source":"European journal of human genetics : EJHG","url":"https://pubmed.ncbi.nlm.nih.gov/35388187","citation_count":19,"is_preprint":false},{"pmid":"7977450","id":"PMC_7977450","title":"Linkage analysis of a candidate locus (HLA) in autosomal dominant sacral defect with anterior meningocele.","date":"1994","source":"American journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/7977450","citation_count":10,"is_preprint":false},{"pmid":"27440996","id":"PMC_27440996","title":"Variation in PTCHD2, CRISP3, NAP1L4, FSCB, and AP3B2 associated with spherical equivalent.","date":"2016","source":"Molecular vision","url":"https://pubmed.ncbi.nlm.nih.gov/27440996","citation_count":9,"is_preprint":false},{"pmid":"9570741","id":"PMC_9570741","title":"Sequence divergence within the sperm-specific polypeptide TCTE1 is correlated with species-specific differences in sperm binding to zona-intact eggs.","date":"1998","source":"Journal of andrology","url":"https://pubmed.ncbi.nlm.nih.gov/9570741","citation_count":8,"is_preprint":false},{"pmid":"39707004","id":"PMC_39707004","title":"Genetic susceptibility of diffuse large B-cell lymphoma: a meta genome-wide association study in Asian population.","date":"2024","source":"Leukemia","url":"https://pubmed.ncbi.nlm.nih.gov/39707004","citation_count":4,"is_preprint":false},{"pmid":"38650655","id":"PMC_38650655","title":"Effects of Tcte1 knockout on energy chain transportation and spermatogenesis: implications for male infertility.","date":"2024","source":"Human reproduction open","url":"https://pubmed.ncbi.nlm.nih.gov/38650655","citation_count":1,"is_preprint":false},{"pmid":"41460250","id":"PMC_41460250","title":"ANKEF1 is a key axonemal component essential for murine sperm motility and male fertility.","date":"2025","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/41460250","citation_count":1,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.12.03.626701","title":"ANKRD5: a key component of the axoneme required for sperm motility and male fertility","date":"2024-12-07","source":"bioRxiv","url":"https://doi.org/10.1101/2024.12.03.626701","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":11591,"output_tokens":1808,"usd":0.030946,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8646,"output_tokens":2217,"usd":0.049328,"stage2_stop_reason":"end_turn"},"total_usd":0.080274,"stage1_batch_id":"msgbatch_01AsR7g8dGTEiEw9U83bJeWn","stage2_batch_id":"msgbatch_01YV5ZyxtFNUZEjxRcpd9jzb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2017,\n      \"finding\": \"TCTE1 (DRC5) is a conserved component of the nexin-dynein regulatory complex (N-DRC) of the axoneme, localized to the flagellum of mouse spermatozoa. Knockout of Tcte1 causes male sterility with aberrant sperm motility despite structurally normal axonemes, and Tcte1-null sperm show a significant decrease in ATP levels, linking TCTE1 to energy metabolism required for dynein motor function.\",\n      \"method\": \"Mouse knockout (Tcte1-null), immunofluorescence localization, ATP measurement, transmission electron microscopy, Northern/Western blot\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO with defined cellular phenotype, protein localization to flagellum, ATP measurement as functional readout, axoneme structural analysis; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"28630322\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TCTE1 (DRC5) interacts with FBXL13 (DRC6) and DRC7 within the N-DRC complex in the mammalian sperm flagellum. DRC7 (but not FBXL13) is required for correct assembly of the N-DRC and for incorporating other N-DRC components, including TCTE1, into the flagellum.\",\n      \"method\": \"Mouse knockout of Drc7 and Fbxl13, immunofluorescence, electron microscopy of axoneme structure, Western blot for N-DRC component localization\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO with defined phenotype and demonstrated loss of N-DRC component incorporation; interaction of TCTE1 with DRC6/DRC7 reported but not independently replicated\",\n      \"pmids\": [\"31961863\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Bi-allelic loss-of-function frameshift variants in human TCTE1/DRC5 cause asthenospermia and male infertility, with structurally normal but low-motility sperm, confirming the conserved requirement of TCTE1 for flagellar motility in humans.\",\n      \"method\": \"Whole-exome sequencing of infertile patient, protein degradation assay (Western blot showing rapid degradation of mutant TCTE1), clinical semen analysis, IVF rescue experiment\",\n      \"journal\": \"European journal of human genetics : EJHG\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — human genetic case with protein-level validation (degradation shown by Western blot), single case but consistent with mouse KO findings\",\n      \"pmids\": [\"35388187\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In Tcte1 knockout mice, Tcte1 protein is present only in residual amounts in the sperm head nucleus and is not transported to the sperm flagella; other N-DRC components (DRC7, FBXL13/DRC6, EPS8L1/DRC3) are also absent from the flagella, indicating TCTE1 is required for N-DRC complex assembly and transport to the flagellum. Knockout causes oligoasthenoteratozoospermia with 2.4-fold reduced sperm ATP and disturbed tail:midpiece ratios. Haploinsufficiency causes oligozoospermia. RNA-seq revealed 21 differentially expressed genes related to mitochondrial ATP processing, apoptosis, or spermatogenesis.\",\n      \"method\": \"CRISPR/Cas9 Tcte1 knockout mice, immunofluorescence localization of N-DRC proteins in sperm, ATP luminescence assay, semen analysis, RNAseq, protein prediction modeling of human variants\",\n      \"journal\": \"Human reproduction open\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR KO with multiple orthogonal methods (localization, ATP, RNAseq, electron microscopy of tail morphology), consistent with prior mouse KO study\",\n      \"pmids\": [\"38650655\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"DRC5/TCTE1 physically interacts with ANKEF1 (ANKRD5) within the N-DRC of the sperm axoneme. This interaction occurs independently of calcium regulation. ANKEF1 deficiency does not alter ATP levels but causes increased structural heterogeneity of doublet microtubules, suggesting TCTE1 participates in N-DRC-mediated mechanical buffering between adjacent doublet microtubules.\",\n      \"method\": \"Co-immunoprecipitation of ANKEF1 with DRC5/TCTE1 and DRC4/GAS8, Ankef1 knockout mice, cryo-electron tomography of sperm axoneme, ATP/ROS/mitochondrial membrane potential measurements\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP interaction with DRC5/TCTE1 in the context of the N-DRC, supported by cryo-ET structural data; single lab, peer-reviewed\",\n      \"pmids\": [\"41460250\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"The N-terminal domain of TCTE1 shows species-specific sequence divergence correlated with heterospecific sperm-egg binding ability, suggesting the TCTE1 sperm polypeptide contributes to species-specific sperm function; the protein is expressed in early stages of spermatogenesis and is absolutely required for fertilization in mouse.\",\n      \"method\": \"Comparative amino acid sequence analysis of TCTE1 N-terminal regions across rodent species; heterospecific sperm-egg binding assay\",\n      \"journal\": \"Journal of andrology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — species comparison and binding assay; no direct mechanistic experiment on the protein's molecular function\",\n      \"pmids\": [\"9570741\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TCTE1/DRC5 is an evolutionarily conserved axonemal protein that forms a structural component of the nexin-dynein regulatory complex (N-DRC) in the sperm flagellum; it is required for N-DRC assembly and transport to the flagellum, for normal sperm ATP production, and for flagellar beating, with loss-of-function causing asthenospermia and male infertility in both mice and humans. TCTE1 physically interacts with DRC6 (FBXL13), DRC7, and ANKEF1 within the N-DRC, contributing to mechanical stability of adjacent doublet microtubules.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TCTE1/DRC5 is an evolutionarily conserved axonemal protein that functions as a structural component of the nexin-dynein regulatory complex (N-DRC) in the sperm flagellum, where it is required for flagellar motility and male fertility [#0]. TCTE1 is required for assembly of the N-DRC and its transport to the flagellum: in its absence the protein is retained only in residual amounts in the sperm head nucleus and other N-DRC subunits (DRC7, FBXL13/DRC6, EPS8L1/DRC3) fail to reach the flagellum [#3]. Within the complex, TCTE1 physically interacts with FBXL13 (DRC6) and DRC7, with DRC7 being required to incorporate TCTE1 and other components into the flagellum [#1], and it also associates with ANKEF1 in a calcium-independent manner, contributing to N-DRC-mediated mechanical buffering between adjacent doublet microtubules [#4]. Loss of TCTE1 produces aberrant sperm motility with reduced sperm ATP levels despite structurally normal axonemes, linking the protein to the energy supply required for dynein motor function [#0, #3]. Bi-allelic loss-of-function variants in human TCTE1 cause asthenospermia and male infertility, establishing a conserved requirement for flagellar motility [#2].\",\n  \"teleology\": [\n    {\n      \"year\": 2017,\n      \"claim\": \"Established TCTE1/DRC5 as a flagellar N-DRC component whose loss causes male sterility, answering whether the protein has a functional role in sperm motility and energy metabolism.\",\n      \"evidence\": \"Tcte1-null mouse knockout with flagellar immunofluorescence, ATP measurement, and axoneme electron microscopy\",\n      \"pmids\": [\"28630322\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mechanism linking TCTE1 loss to reduced ATP not defined\",\n        \"Direct binding partners within the N-DRC not yet identified\",\n        \"Whether axoneme is biochemically as well as structurally intact unresolved\"\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Defined TCTE1's molecular partners and assembly hierarchy, showing it interacts with FBXL13 and DRC7 and that DRC7 is required to incorporate TCTE1 into the flagellum.\",\n      \"evidence\": \"Drc7 and Fbxl13 knockout mice with immunofluorescence and Western blot for N-DRC component localization\",\n      \"pmids\": [\"31961863\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"TCTE1-DRC6/DRC7 interactions not independently replicated\",\n        \"Direct vs indirect nature of interactions not resolved\",\n        \"Stoichiometry within N-DRC unknown\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Extended the requirement for TCTE1 to humans, showing bi-allelic loss-of-function variants cause asthenospermia and infertility.\",\n      \"evidence\": \"Whole-exome sequencing of an infertile patient with protein degradation assay and clinical semen analysis\",\n      \"pmids\": [\"35388187\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single human case limits genotype-phenotype generalization\",\n        \"No structural analysis of patient sperm axonemes\",\n        \"Mechanism of mutant protein degradation not characterized\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Demonstrated that TCTE1 is required for N-DRC assembly and transport to the flagellum, with broader effects on sperm morphology, ATP, and gene expression.\",\n      \"evidence\": \"CRISPR/Cas9 Tcte1 knockout mice with N-DRC protein localization, ATP luminescence assay, semen analysis, and RNA-seq\",\n      \"pmids\": [\"38650655\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Why residual TCTE1 localizes to the sperm head nucleus unexplained\",\n        \"Causal link between transcriptional changes and phenotype not established\",\n        \"Order of N-DRC subunit recruitment not fully mapped\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified ANKEF1 as a calcium-independent TCTE1 partner and connected the complex to mechanical buffering of doublet microtubules.\",\n      \"evidence\": \"Co-immunoprecipitation of ANKEF1 with DRC5/TCTE1 and DRC4/GAS8, Ankef1 knockout mice, and cryo-electron tomography\",\n      \"pmids\": [\"41460250\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Co-IP not reciprocally validated for direct binding\",\n        \"Functional consequence of TCTE1-ANKEF1 interaction for motility untested\",\n        \"Whether mechanical buffering is mediated by TCTE1 itself unresolved\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How TCTE1 mechanistically couples N-DRC integrity to sperm ATP levels and dynein motor regulation remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No structural model of TCTE1 within the assembled N-DRC\",\n        \"Mechanism connecting TCTE1 loss to reduced ATP undefined\",\n        \"Direct biochemical demonstration of TCTE1 binding interfaces lacking\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0, 3, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005930\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [0, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [0, 2, 3]}\n    ],\n    \"complexes\": [\n      \"nexin-dynein regulatory complex (N-DRC)\"\n    ],\n    \"partners\": [\n      \"FBXL13\",\n      \"DRC7\",\n      \"ANKEF1\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}