{"gene":"DNAJB13","run_date":"2026-06-09T23:54:42","timeline":{"discoveries":[{"year":2004,"finding":"DNAJB13 (then called TSARG6) encodes a protein containing a conserved J domain, placing it in the HSP40/DnaJ family; the J domain is critical for DnaJ-DnaK (HSP40-HSP70) protein-protein interactions, establishing DNAJB13 as an HSP40 co-chaperone.","method":"Molecular cloning, sequence analysis, RT-PCR, Northern blot","journal":"Acta biochimica et biophysica Sinica","confidence":"Low","confidence_rationale":"Tier 4 / Weak — sequence-based inference only; no biochemical interaction assay performed for the J domain function in this paper","pmids":["14970903"],"is_preprint":false},{"year":2008,"finding":"DNAJB13 is localized to the axoneme of mouse sperm flagella. It is present along the entire flagellum but absent from SDS-resistant tail structures lacking the axoneme, establishing it as an axoneme-associated component. Expression is constitutive and not heat-shock-induced.","method":"Western blot, immunohistochemistry, subcellular fractionation of sperm tail structures with specific antibody","journal":"Molecular reproduction and development","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by fractionation and immunohistochemistry, single lab, two orthogonal methods","pmids":["18247331"],"is_preprint":false},{"year":2010,"finding":"DNAJB13 localizes specifically to the radial spokes of the mouse '9+2' axoneme in sperm flagella, and is also present in motile cilia of trachea and oviduct.","method":"Immunoelectron microscopy of mouse sperm flagella; immunohistochemistry on trachea and oviduct sections","journal":"Reproduction in domestic animals","confidence":"High","confidence_rationale":"Tier 1 / Moderate — immunoelectron microscopy with subcellular resolution establishing radial spoke localization, confirmed in multiple tissue types, single lab","pmids":["19919626"],"is_preprint":false},{"year":2016,"finding":"A missense mutation (p.Met278Arg) in DNAJB13 causes protein instability and proteasomal degradation, resulting in absence of DNAJB13 from cilia and sperm axonemes and leading to central complex (CC) defects and PCD. A second splice-site mutation (c.68+1G>C) causes a splicing defect and loss-of-function. These findings establish DNAJB13 as essential for proper formation and function of the ciliary/flagellar axoneme central complex in humans.","method":"In vitro expression studies of mutant protein, proteasome inhibition assays, whole-exome sequencing, SNP genotyping, transcript analysis from airway cells, immunofluorescence of patient cilia and sperm","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — in vitro protein stability assay with mutant confirmed by absence of endogenous protein in patient tissue, two independent mutations in two families, multiple orthogonal methods","pmids":["27486783"],"is_preprint":false},{"year":2016,"finding":"DNAJB13 physically interacts with hexokinase 1 (HK1) in mouse testis, suggesting a role in regulating sperm motility through interaction with a glycolytic enzyme.","method":"GST pull-down assay using recombinant GST-DNAJB13 fusion protein with mouse testis lysate, followed by Western blot detection of HK1","journal":"Nan fang yi ke da xue xue bao (Journal of Southern Medical University)","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single GST pull-down, no reciprocal Co-IP, single lab, single method","pmids":["27998865"],"is_preprint":false},{"year":2019,"finding":"A heterozygous missense mutation (c.106T>C) in DNAJB13 reduces DNAJB13 protein levels and is associated with sperm tail ultrastructural defects and immotile spermatozoa in asthenozoospermia patients. Co-immunoprecipitation and mass spectrometry identified DNAJB13-interacting partners in sperm.","method":"Co-immunoprecipitation, mass spectrometric detection, immunoelectron microscopy, transmission electron microscopy, multiple reaction monitoring (MRM) for protein quantification, indirect immunofluorescence","journal":"Andrology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — MRM quantification of reduced protein levels, co-IP/MS interactome, TEM ultrastructure, single lab with multiple orthogonal methods","pmids":["31342671"],"is_preprint":false},{"year":2022,"finding":"A homozygous frameshift mutation (c.335_336del, p.E112Vfs*3) in DNAJB13 abolishes DNAJB13 protein expression in spermatozoa and causes sperm ultrastructural defects and teratozoospermia with recurrent respiratory infections. DNAJB13 is expressed in the cytoplasm of primary germ cells and in flagella of spermatids during human and mouse spermiogenesis.","method":"Whole-exome sequencing, immunofluorescence staining, Western blotting, transmission electron microscopy","journal":"Journal of assisted reproduction and genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function mutation confirmed by Western blot absence of protein and TEM ultrastructural defects, single lab, multiple orthogonal methods","pmids":["35166991"],"is_preprint":false},{"year":2024,"finding":"DNAJB13 physically interacts with DNAH12, a special inner dynein arm component. DNAH12 deficiency disrupts recruitment of DNALI1 and DNAH1 to inner dynein arms and impairs central pair stability in a manner that involves DNAJB13 (along with RSPH1 and RSPH9), placing DNAJB13 within the radial spoke head protein network that regulates central pair stability.","method":"Co-immunoprecipitation (interaction between DNAH12 and DNAJB13/RSPH1/RSPH9 demonstrated), mouse knockout models (Dnah12−/− and Dnah12mut/mut), TEM, immunofluorescence","journal":"bioRxiv (preprint)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP interaction demonstrated, supported by KO mouse model and TEM, but preprint not yet peer-reviewed","pmids":["bio_10.1101_2024.06.20.599934"],"is_preprint":true}],"current_model":"DNAJB13 is an HSP40 co-chaperone that localizes to the radial spokes of the '9+2' axoneme in motile cilia and sperm flagella, where it is essential for central complex stability and axonemal integrity; loss-of-function mutations cause proteasomal degradation of the protein, leading to central complex defects, primary ciliary dyskinesia, and male infertility, while its interactions with HK1 and (via DNAH12) with other radial spoke head proteins (RSPH1, RSPH9) suggest additional roles in sperm motility regulation."},"narrative":{"mechanistic_narrative":"DNAJB13 is an HSP40/DnaJ-family co-chaperone that functions as a structural component of the radial spokes of the '9+2' axoneme in motile cilia and sperm flagella, where it is required for central complex stability and axonemal integrity [PMID:19919626, PMID:27486783]. It is an axoneme-associated protein distributed along the entire sperm flagellum and present in motile cilia of trachea and oviduct, with constitutive (non-heat-shock-induced) expression [PMID:18247331, PMID:19919626]. Loss-of-function mutations destabilize the protein and trigger its proteasomal degradation, producing absence of DNAJB13 from cilia and sperm axonemes, central complex defects, primary ciliary dyskinesia, and male infertility spanning asthenozoospermia and teratozoospermia [PMID:27486783, PMID:31342671, PMID:35166991]. Within the axoneme it sits in a radial spoke head protein network: it physically interacts with DNAH12, an inner dynein arm component whose loss disrupts central pair stability in a manner involving DNAJB13 together with RSPH1 and RSPH9 [PMID:bio_10.1101_2024.06.20.599934]. The biochemical chaperone activity predicted from its conserved J domain has not been experimentally demonstrated in the available corpus, and its reported interaction with the glycolytic enzyme HK1 rests on a single pull-down [PMID:14970903, PMID:27998865].","teleology":[{"year":2004,"claim":"Established the molecular identity of DNAJB13 by placing it in the HSP40/DnaJ family via a conserved J domain, framing it as a candidate HSP70 co-chaperone.","evidence":"Molecular cloning, sequence analysis, RT-PCR and Northern blot of TSARG6","pmids":["14970903"],"confidence":"Low","gaps":["Sequence-based inference only — no biochemical assay of J-domain function or HSP70 binding","No subcellular or tissue localization established","No functional phenotype linked"]},{"year":2008,"claim":"Resolved where DNAJB13 acts by showing it is an axoneme-associated component of the sperm flagellum rather than a heat-inducible stress chaperone.","evidence":"Western blot, immunohistochemistry and fractionation of SDS-resistant sperm tail structures in mouse","pmids":["18247331"],"confidence":"Medium","gaps":["Did not resolve the specific axonemal substructure","No mechanistic role demonstrated","Single lab"]},{"year":2010,"claim":"Pinpointed DNAJB13 to the radial spokes of the '9+2' axoneme, defining its precise structural position in both flagella and motile cilia.","evidence":"Immunoelectron microscopy of mouse sperm flagella and immunohistochemistry of trachea and oviduct","pmids":["19919626"],"confidence":"High","gaps":["Did not define radial spoke binding partners","No functional consequence of localization tested","Single lab"]},{"year":2016,"claim":"Established DNAJB13 as causative for human disease by showing loss-of-function mutations destabilize the protein, drive its proteasomal degradation, and produce central complex defects and PCD.","evidence":"In vitro mutant expression and proteasome inhibition, whole-exome sequencing, transcript analysis, and immunofluorescence of patient cilia/sperm across two families","pmids":["27486783"],"confidence":"High","gaps":["Molecular mechanism by which DNAJB13 loss causes central complex collapse not defined","Chaperone client proteins not identified","No structural model of DNAJB13 in the spoke"]},{"year":2016,"claim":"Probed a possible metabolic role by detecting an interaction between DNAJB13 and the glycolytic enzyme HK1 in testis.","evidence":"GST pull-down with recombinant DNAJB13 against mouse testis lysate, Western blot detection of HK1","pmids":["27998865"],"confidence":"Low","gaps":["Single pull-down without reciprocal Co-IP or in vivo validation","Functional consequence for motility untested","Whether interaction reflects chaperone-client relationship unknown"]},{"year":2019,"claim":"Extended the disease spectrum and began mapping the sperm interactome, linking a missense allele to reduced DNAJB13 levels, tail ultrastructural defects, and immotile sperm in asthenozoospermia.","evidence":"Co-IP/mass spectrometry interactome, MRM protein quantification, TEM and immuno-EM of patient sperm","pmids":["31342671"],"confidence":"Medium","gaps":["Interactome partners not individually validated","Genotype-phenotype mechanism for heterozygous allele not resolved","Single lab"]},{"year":2022,"claim":"Confirmed loss of DNAJB13 expression as a cause of teratozoospermia with respiratory disease and clarified its developmental expression during spermiogenesis.","evidence":"Whole-exome sequencing, Western blot showing protein absence, immunofluorescence, and TEM in human and mouse","pmids":["35166991"],"confidence":"Medium","gaps":["Does not explain variable phenotype across alleles","No molecular pathway from DNAJB13 loss to flagellar malformation","Single lab"]},{"year":2024,"claim":"Positioned DNAJB13 within a radial spoke head network by showing it physically interacts with the inner dynein arm component DNAH12 and participates with RSPH1/RSPH9 in central pair stability.","evidence":"Co-IP, Dnah12 knockout and mutant mouse models, TEM and immunofluorescence (preprint)","pmids":["bio_10.1101_2024.06.20.599934"],"confidence":"Medium","gaps":["Preprint, not yet peer-reviewed","Directness and stoichiometry of DNAJB13-DNAH12 interaction not resolved","Whether DNAJB13 acts as chaperone for these partners untested"]},{"year":null,"claim":"Whether DNAJB13 exerts a bona fide HSP40 chaperone activity — and what its client proteins are within the radial spoke — remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No demonstrated HSP70 partnership or J-domain-dependent folding activity","No identified chaperone clients among axonemal proteins","No structural model of DNAJB13 within the radial spoke"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0044183","term_label":"protein folding chaperone","supporting_discovery_ids":[0]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[2,3]}],"localization":[{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[2,3]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[1,2]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[6]}],"pathway":[{"term_id":"R-HSA-1474244","term_label":"Extracellular matrix organization","supporting_discovery_ids":[3]}],"complexes":["radial spoke"],"partners":["DNAH12","RSPH1","RSPH9","HK1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P59910","full_name":"DnaJ homolog subfamily B member 13","aliases":["Testis and spermatogenesis cell-related protein 6","Testis spermatocyte apoptosis-related gene 6 protein","Testis spermatogenesis apoptosis-related gene 3 protein","Testis spermatogenesis apoptosis-related gene 6 protein"],"length_aa":316,"mass_kda":36.1,"function":"Functions as part of axonemal radial spoke complexes that play an important part in the motility of sperm and cilia","subcellular_location":"Cell projection, cilium, flagellum","url":"https://www.uniprot.org/uniprotkb/P59910/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/DNAJB13","classification":"Not Classified","n_dependent_lines":13,"n_total_lines":1208,"dependency_fraction":0.01076158940397351},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/DNAJB13","total_profiled":1310},"omim":[{"mim_id":"617091","title":"CILIARY DYSKINESIA, PRIMARY, 34; CILD34","url":"https://www.omim.org/entry/617091"},{"mim_id":"610263","title":"DNAJ/HSP40 HOMOLOG, SUBFAMILY B, MEMBER 13; DNAJB13","url":"https://www.omim.org/entry/610263"},{"mim_id":"603340","title":"DYNEIN, AXONEMAL, HEAVY CHAIN 12; DNAH12","url":"https://www.omim.org/entry/603340"},{"mim_id":"244400","title":"CILIARY DYSKINESIA, PRIMARY, 1; CILD1","url":"https://www.omim.org/entry/244400"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Plasma membrane","reliability":"Uncertain"},{"location":"Mid piece","reliability":"Uncertain"},{"location":"Principal piece","reliability":"Uncertain"},{"location":"End piece","reliability":"Uncertain"},{"location":"Nucleoli","reliability":"Additional"},{"location":"Nucleoli rim","reliability":"Additional"},{"location":"Mitotic chromosome","reliability":"Additional"},{"location":"Vesicles","reliability":"Additional"},{"location":"Primary cilium","reliability":"Additional"},{"location":"Primary cilium tip","reliability":"Additional"}],"tissue_specificity":"Group enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"choroid plexus","ntpm":25.4},{"tissue":"fallopian tube","ntpm":50.1},{"tissue":"testis","ntpm":18.0}],"url":"https://www.proteinatlas.org/search/DNAJB13"},"hgnc":{"alias_symbol":["TSARG6","RSPH16A"],"prev_symbol":[]},"alphafold":{"accession":"P59910","domains":[{"cath_id":"1.10.287.110","chopping":"6-105","consensus_level":"high","plddt":81.998,"start":6,"end":105},{"cath_id":"2.60.260.20","chopping":"137-218","consensus_level":"high","plddt":93.2334,"start":137,"end":218},{"cath_id":"2.60.260.20","chopping":"224-298","consensus_level":"high","plddt":96.788,"start":224,"end":298}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P59910","model_url":"https://alphafold.ebi.ac.uk/files/AF-P59910-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P59910-F1-predicted_aligned_error_v6.png","plddt_mean":86.25},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=DNAJB13","jax_strain_url":"https://www.jax.org/strain/search?query=DNAJB13"},"sequence":{"accession":"P59910","fasta_url":"https://rest.uniprot.org/uniprotkb/P59910.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P59910/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P59910"}},"corpus_meta":[{"pmid":"27486783","id":"PMC_27486783","title":"Mutations in DNAJB13, Encoding an HSP40 Family Member, Cause Primary Ciliary Dyskinesia and Male Infertility.","date":"2016","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/27486783","citation_count":77,"is_preprint":false},{"pmid":"18247331","id":"PMC_18247331","title":"A heat-shock protein 40, DNAJB13, is an axoneme-associated component in mouse spermatozoa.","date":"2008","source":"Molecular reproduction and development","url":"https://pubmed.ncbi.nlm.nih.gov/18247331","citation_count":30,"is_preprint":false},{"pmid":"31342671","id":"PMC_31342671","title":"Missense mutation in DNAJB13 gene correlated with male fertility in asthenozoospermia.","date":"2019","source":"Andrology","url":"https://pubmed.ncbi.nlm.nih.gov/31342671","citation_count":22,"is_preprint":false},{"pmid":"19919626","id":"PMC_19919626","title":"DNAJB13 is a radial spoke protein of mouse '9+2' axoneme.","date":"2010","source":"Reproduction in domestic animals = Zuchthygiene","url":"https://pubmed.ncbi.nlm.nih.gov/19919626","citation_count":20,"is_preprint":false},{"pmid":"25233908","id":"PMC_25233908","title":"DNAJB13, a type II HSP40 family member, localizes to the spermatids and spermatozoa during mouse spermatogenesis.","date":"2014","source":"BMC developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/25233908","citation_count":20,"is_preprint":false},{"pmid":"14970903","id":"PMC_14970903","title":"Molecular cloning of TSARG6 gene related to apoptosis in human spermatogenic cells.","date":"2004","source":"Acta biochimica et biophysica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/14970903","citation_count":15,"is_preprint":false},{"pmid":"35166991","id":"PMC_35166991","title":"A novel homozygous mutation in DNAJB13-a gene associated with the sperm axoneme-leads to teratozoospermia.","date":"2022","source":"Journal of assisted reproduction and genetics","url":"https://pubmed.ncbi.nlm.nih.gov/35166991","citation_count":11,"is_preprint":false},{"pmid":"33346962","id":"PMC_33346962","title":"[Expression of Dnajb13 and its involvement in the apoptosis of spermatogenic cells in the testis of the mouse with cryptorchidism].","date":"2020","source":"Zhonghua nan ke xue = National journal of andrology","url":"https://pubmed.ncbi.nlm.nih.gov/33346962","citation_count":1,"is_preprint":false},{"pmid":"27998865","id":"PMC_27998865","title":"[Interaction of DNAJB13 with HK1 in mouse].","date":"2016","source":"Nan fang yi ke da xue xue bao = Journal of Southern Medical University","url":"https://pubmed.ncbi.nlm.nih.gov/27998865","citation_count":1,"is_preprint":false},{"pmid":"41413469","id":"PMC_41413469","title":"DNAJB13 polymorphisms and association with idiopathic asthenozoospermia in Sichuan, China.","date":"2025","source":"Basic and clinical andrology","url":"https://pubmed.ncbi.nlm.nih.gov/41413469","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.06.20.599934","title":"Deficiency in DNAH12 causes male infertility by impairing DNAH1 and DNALI1 recruitment in humans and mice","date":"2024-06-23","source":"bioRxiv","url":"https://doi.org/10.1101/2024.06.20.599934","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7667,"output_tokens":2076,"usd":0.027071,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9018,"output_tokens":2741,"usd":0.056807,"stage2_stop_reason":"end_turn"},"total_usd":0.083878,"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\": 2004,\n      \"finding\": \"DNAJB13 (then called TSARG6) encodes a protein containing a conserved J domain, placing it in the HSP40/DnaJ family; the J domain is critical for DnaJ-DnaK (HSP40-HSP70) protein-protein interactions, establishing DNAJB13 as an HSP40 co-chaperone.\",\n      \"method\": \"Molecular cloning, sequence analysis, RT-PCR, Northern blot\",\n      \"journal\": \"Acta biochimica et biophysica Sinica\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — sequence-based inference only; no biochemical interaction assay performed for the J domain function in this paper\",\n      \"pmids\": [\"14970903\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"DNAJB13 is localized to the axoneme of mouse sperm flagella. It is present along the entire flagellum but absent from SDS-resistant tail structures lacking the axoneme, establishing it as an axoneme-associated component. Expression is constitutive and not heat-shock-induced.\",\n      \"method\": \"Western blot, immunohistochemistry, subcellular fractionation of sperm tail structures with specific antibody\",\n      \"journal\": \"Molecular reproduction and development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization by fractionation and immunohistochemistry, single lab, two orthogonal methods\",\n      \"pmids\": [\"18247331\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"DNAJB13 localizes specifically to the radial spokes of the mouse '9+2' axoneme in sperm flagella, and is also present in motile cilia of trachea and oviduct.\",\n      \"method\": \"Immunoelectron microscopy of mouse sperm flagella; immunohistochemistry on trachea and oviduct sections\",\n      \"journal\": \"Reproduction in domestic animals\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — immunoelectron microscopy with subcellular resolution establishing radial spoke localization, confirmed in multiple tissue types, single lab\",\n      \"pmids\": [\"19919626\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"A missense mutation (p.Met278Arg) in DNAJB13 causes protein instability and proteasomal degradation, resulting in absence of DNAJB13 from cilia and sperm axonemes and leading to central complex (CC) defects and PCD. A second splice-site mutation (c.68+1G>C) causes a splicing defect and loss-of-function. These findings establish DNAJB13 as essential for proper formation and function of the ciliary/flagellar axoneme central complex in humans.\",\n      \"method\": \"In vitro expression studies of mutant protein, proteasome inhibition assays, whole-exome sequencing, SNP genotyping, transcript analysis from airway cells, immunofluorescence of patient cilia and sperm\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — in vitro protein stability assay with mutant confirmed by absence of endogenous protein in patient tissue, two independent mutations in two families, multiple orthogonal methods\",\n      \"pmids\": [\"27486783\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"DNAJB13 physically interacts with hexokinase 1 (HK1) in mouse testis, suggesting a role in regulating sperm motility through interaction with a glycolytic enzyme.\",\n      \"method\": \"GST pull-down assay using recombinant GST-DNAJB13 fusion protein with mouse testis lysate, followed by Western blot detection of HK1\",\n      \"journal\": \"Nan fang yi ke da xue xue bao (Journal of Southern Medical University)\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single GST pull-down, no reciprocal Co-IP, single lab, single method\",\n      \"pmids\": [\"27998865\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"A heterozygous missense mutation (c.106T>C) in DNAJB13 reduces DNAJB13 protein levels and is associated with sperm tail ultrastructural defects and immotile spermatozoa in asthenozoospermia patients. Co-immunoprecipitation and mass spectrometry identified DNAJB13-interacting partners in sperm.\",\n      \"method\": \"Co-immunoprecipitation, mass spectrometric detection, immunoelectron microscopy, transmission electron microscopy, multiple reaction monitoring (MRM) for protein quantification, indirect immunofluorescence\",\n      \"journal\": \"Andrology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — MRM quantification of reduced protein levels, co-IP/MS interactome, TEM ultrastructure, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"31342671\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"A homozygous frameshift mutation (c.335_336del, p.E112Vfs*3) in DNAJB13 abolishes DNAJB13 protein expression in spermatozoa and causes sperm ultrastructural defects and teratozoospermia with recurrent respiratory infections. DNAJB13 is expressed in the cytoplasm of primary germ cells and in flagella of spermatids during human and mouse spermiogenesis.\",\n      \"method\": \"Whole-exome sequencing, immunofluorescence staining, Western blotting, transmission electron microscopy\",\n      \"journal\": \"Journal of assisted reproduction and genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function mutation confirmed by Western blot absence of protein and TEM ultrastructural defects, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"35166991\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"DNAJB13 physically interacts with DNAH12, a special inner dynein arm component. DNAH12 deficiency disrupts recruitment of DNALI1 and DNAH1 to inner dynein arms and impairs central pair stability in a manner that involves DNAJB13 (along with RSPH1 and RSPH9), placing DNAJB13 within the radial spoke head protein network that regulates central pair stability.\",\n      \"method\": \"Co-immunoprecipitation (interaction between DNAH12 and DNAJB13/RSPH1/RSPH9 demonstrated), mouse knockout models (Dnah12−/− and Dnah12mut/mut), TEM, immunofluorescence\",\n      \"journal\": \"bioRxiv (preprint)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP interaction demonstrated, supported by KO mouse model and TEM, but preprint not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2024.06.20.599934\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"DNAJB13 is an HSP40 co-chaperone that localizes to the radial spokes of the '9+2' axoneme in motile cilia and sperm flagella, where it is essential for central complex stability and axonemal integrity; loss-of-function mutations cause proteasomal degradation of the protein, leading to central complex defects, primary ciliary dyskinesia, and male infertility, while its interactions with HK1 and (via DNAH12) with other radial spoke head proteins (RSPH1, RSPH9) suggest additional roles in sperm motility regulation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"DNAJB13 is an HSP40/DnaJ-family co-chaperone that functions as a structural component of the radial spokes of the '9+2' axoneme in motile cilia and sperm flagella, where it is required for central complex stability and axonemal integrity [#2, #3]. It is an axoneme-associated protein distributed along the entire sperm flagellum and present in motile cilia of trachea and oviduct, with constitutive (non-heat-shock-induced) expression [#1, #2]. Loss-of-function mutations destabilize the protein and trigger its proteasomal degradation, producing absence of DNAJB13 from cilia and sperm axonemes, central complex defects, primary ciliary dyskinesia, and male infertility spanning asthenozoospermia and teratozoospermia [#3, #5, #6]. Within the axoneme it sits in a radial spoke head protein network: it physically interacts with DNAH12, an inner dynein arm component whose loss disrupts central pair stability in a manner involving DNAJB13 together with RSPH1 and RSPH9 [#7]. The biochemical chaperone activity predicted from its conserved J domain has not been experimentally demonstrated in the available corpus, and its reported interaction with the glycolytic enzyme HK1 rests on a single pull-down [#0, #4].\",\n  \"teleology\": [\n    {\n      \"year\": 2004,\n      \"claim\": \"Established the molecular identity of DNAJB13 by placing it in the HSP40/DnaJ family via a conserved J domain, framing it as a candidate HSP70 co-chaperone.\",\n      \"evidence\": \"Molecular cloning, sequence analysis, RT-PCR and Northern blot of TSARG6\",\n      \"pmids\": [\"14970903\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Sequence-based inference only — no biochemical assay of J-domain function or HSP70 binding\", \"No subcellular or tissue localization established\", \"No functional phenotype linked\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Resolved where DNAJB13 acts by showing it is an axoneme-associated component of the sperm flagellum rather than a heat-inducible stress chaperone.\",\n      \"evidence\": \"Western blot, immunohistochemistry and fractionation of SDS-resistant sperm tail structures in mouse\",\n      \"pmids\": [\"18247331\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not resolve the specific axonemal substructure\", \"No mechanistic role demonstrated\", \"Single lab\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Pinpointed DNAJB13 to the radial spokes of the '9+2' axoneme, defining its precise structural position in both flagella and motile cilia.\",\n      \"evidence\": \"Immunoelectron microscopy of mouse sperm flagella and immunohistochemistry of trachea and oviduct\",\n      \"pmids\": [\"19919626\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define radial spoke binding partners\", \"No functional consequence of localization tested\", \"Single lab\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Established DNAJB13 as causative for human disease by showing loss-of-function mutations destabilize the protein, drive its proteasomal degradation, and produce central complex defects and PCD.\",\n      \"evidence\": \"In vitro mutant expression and proteasome inhibition, whole-exome sequencing, transcript analysis, and immunofluorescence of patient cilia/sperm across two families\",\n      \"pmids\": [\"27486783\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism by which DNAJB13 loss causes central complex collapse not defined\", \"Chaperone client proteins not identified\", \"No structural model of DNAJB13 in the spoke\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Probed a possible metabolic role by detecting an interaction between DNAJB13 and the glycolytic enzyme HK1 in testis.\",\n      \"evidence\": \"GST pull-down with recombinant DNAJB13 against mouse testis lysate, Western blot detection of HK1\",\n      \"pmids\": [\"27998865\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single pull-down without reciprocal Co-IP or in vivo validation\", \"Functional consequence for motility untested\", \"Whether interaction reflects chaperone-client relationship unknown\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Extended the disease spectrum and began mapping the sperm interactome, linking a missense allele to reduced DNAJB13 levels, tail ultrastructural defects, and immotile sperm in asthenozoospermia.\",\n      \"evidence\": \"Co-IP/mass spectrometry interactome, MRM protein quantification, TEM and immuno-EM of patient sperm\",\n      \"pmids\": [\"31342671\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Interactome partners not individually validated\", \"Genotype-phenotype mechanism for heterozygous allele not resolved\", \"Single lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Confirmed loss of DNAJB13 expression as a cause of teratozoospermia with respiratory disease and clarified its developmental expression during spermiogenesis.\",\n      \"evidence\": \"Whole-exome sequencing, Western blot showing protein absence, immunofluorescence, and TEM in human and mouse\",\n      \"pmids\": [\"35166991\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not explain variable phenotype across alleles\", \"No molecular pathway from DNAJB13 loss to flagellar malformation\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Positioned DNAJB13 within a radial spoke head network by showing it physically interacts with the inner dynein arm component DNAH12 and participates with RSPH1/RSPH9 in central pair stability.\",\n      \"evidence\": \"Co-IP, Dnah12 knockout and mutant mouse models, TEM and immunofluorescence (preprint)\",\n      \"pmids\": [\"bio_10.1101_2024.06.20.599934\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Preprint, not yet peer-reviewed\", \"Directness and stoichiometry of DNAJB13-DNAH12 interaction not resolved\", \"Whether DNAJB13 acts as chaperone for these partners untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Whether DNAJB13 exerts a bona fide HSP40 chaperone activity — and what its client proteins are within the radial spoke — remains unresolved.\",\n      \"evidence\": null,\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No demonstrated HSP70 partnership or J-domain-dependent folding activity\", \"No identified chaperone clients among axonemal proteins\", \"No structural model of DNAJB13 within the radial spoke\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0044183\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [2, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [2, 3]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474244\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"complexes\": [\"radial spoke\"],\n    \"partners\": [\"DNAH12\", \"RSPH1\", \"RSPH9\", \"HK1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":3,"faith_total":3,"faith_pct":100.0}}