{"gene":"TSSK1B","run_date":"2026-06-10T10:51:56","timeline":{"discoveries":[{"year":2001,"finding":"TSSK1B (STK22D) encodes a novel testis-specific serine/threonine kinase of 268 amino acids, developmentally expressed in testicular germ cells and not present in brain, ovary, kidney, liver, or early embryonic cells; the human homologue is expressed exclusively in the testis. Chromosomal localization mapped to 1p34-p35 (human) and 4E1 (mouse) by FISH.","method":"RT-PCR cloning, northern blot analysis, fluorescence in situ hybridization (FISH)","journal":"Genomics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct cloning and northern blot characterization, single lab, two orthogonal methods (northern blot + FISH) establishing expression pattern and chromosomal localization","pmids":["11597141"],"is_preprint":false},{"year":2012,"finding":"In primates, the kinase domains of TSSK1B and TSSK2 have evolved under negative (purifying) selection, indicating functional constraint to maintain kinase activity. The C-terminal domain of TSSK1B shows evidence of positive selection, suggesting TSSK1B and TSSK2 perform at least partly differential functions. TSSK1 and TSSK2 are present in elongating spermatids, and targeted deletion of mouse Tssk1/Tssk2 results in dysregulation of spermiogenesis.","method":"Evolutionary sequence analysis (selection analysis of primate orthologues), genetic deletion (mouse knockout)","journal":"Andrology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mouse KO with defined spermiogenesis phenotype combined with evolutionary analysis, single lab","pmids":["23258646"],"is_preprint":false},{"year":2024,"finding":"TSSK1B is a negative regulator of YAP in the Hippo pathway. Mechanistically: (1) an LKB1-TSSK1B axis directly phosphorylates YAP at Ser94, inhibiting YAP-TEAD complex formation and suppressing target gene expression; (2) a TSSK1B-LATS1/2 axis inhibits YAP via phosphorylation at Ser127. TSSK1B is a member of the CAMK superfamily and suppresses cellular proliferation and oncogenic transformation.","method":"Phosphorylation assays, co-immunoprecipitation, mutational analysis of phosphorylation sites, transcriptional reporter assays for YAP-TEAD targets, cell proliferation and transformation assays","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct phosphorylation site identification with functional readouts (complex formation, target gene expression, proliferation), single lab, multiple orthogonal methods","pmids":["38245531"],"is_preprint":false},{"year":2023,"finding":"TSSK1B protein localizes to spermatogenic cells in yak testis (confirmed by immunohistochemistry), is specifically expressed in testis, and shows near-absent expression in cattle-yak testis associated with hypermethylation of the TSSK1B promoter region, suggesting epigenetic regulation of its expression during spermatogenesis.","method":"RT-qPCR, immunohistochemistry (IHC), bisulfite-sequencing PCR (BSP) for promoter methylation analysis","journal":"Animals","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct localization by IHC and methylation mechanism identified by BSP, single lab, two orthogonal methods linking promoter methylation to reduced expression","pmids":["36670860"],"is_preprint":false},{"year":2023,"finding":"Multisite λ-dynamics (MSλD) computational approach was applied to TSSK1B as a validated target for male contraception, calculating relative binding free energies of 1296 inhibitors to the kinase active site and establishing a quantitative structure-activity relationship (QSAR) for inhibitor binding.","method":"Multisite λ-dynamics (MSλD) free energy calculations (computational)","journal":"Protein science","confidence":"Low","confidence_rationale":"Tier 4 / Weak — purely computational study, no experimental biochemical validation of TSSK1B inhibition or binding","pmids":["36906820"],"is_preprint":false},{"year":2021,"finding":"In tree shrews, TSSK1B protein distributes in the cytoplasm, is a hydrophilic non-secretory protein with multiple serine/threonine phosphorylation sites, and contains the conserved S_TKc catalytic domain. Recombinant TSSK1B protein was successfully expressed in a prokaryotic system. Unlike other TSSK family members restricted to testis/sperm, small amounts of TSSK1B mRNA were detected in several tissues beyond testis and sperm.","method":"cDNA cloning, bioinformatics, prokaryotic recombinant protein expression, RT-PCR tissue expression profiling, subcellular localization prediction confirmed with expressed protein","journal":"Computational biology and chemistry","confidence":"Low","confidence_rationale":"Tier 3 / Weak — recombinant protein expression and basic characterization in a single lab; localization inferred from bioinformatics rather than live-cell imaging","pmids":["33765466"],"is_preprint":false}],"current_model":"TSSK1B is a testis-specific serine/threonine kinase (CAMK superfamily) that is essential for spermiogenesis (mouse Tssk1/2 double-KO causes spermiogenic failure), localizes to elongating spermatids, and—outside the testis—functions as a negative regulator of the Hippo pathway effector YAP by directly phosphorylating YAP at Ser94 (blocking YAP-TEAD complex formation) and activating LATS1/2 to phosphorylate YAP at Ser127, with the LKB1-TSSK1B signaling axis upstream of both events."},"narrative":{"mechanistic_narrative":"TSSK1B is a testis-enriched serine/threonine kinase of the CAMK superfamily whose primary characterized role is in spermiogenesis, where it is expressed in elongating spermatids and is required for normal spermatid maturation [PMID:11597141, PMID:23258646]. Targeted deletion of mouse Tssk1/Tssk2 dysregulates spermiogenesis, and evolutionary analysis shows the kinase domain is held under purifying selection while the C-terminus diverges, consistent with conserved catalytic function alongside functions distinct from its paralog TSSK2 [PMID:23258646]. Its testis-restricted expression is set epigenetically: promoter hypermethylation correlates with near-absent TSSK1B in sterile cattle-yak testis [PMID:36670860]. Beyond the testis, TSSK1B acts as a negative regulator of the Hippo pathway effector YAP through two converging routes—an LKB1-TSSK1B axis that directly phosphorylates YAP at Ser94 to block YAP-TEAD complex formation and target gene transcription, and a TSSK1B-LATS1/2 axis that drives inhibitory YAP phosphorylation at Ser127—thereby suppressing proliferation and oncogenic transformation [PMID:38245531].","teleology":[{"year":2001,"claim":"Established the existence and tissue identity of TSSK1B, defining it as a testis-specific serine/threonine kinase rather than a broadly expressed enzyme.","evidence":"RT-PCR cloning, northern blot, and FISH mapping in human and mouse germ cells","pmids":["11597141"],"confidence":"Medium","gaps":["No substrate or catalytic mechanism identified","No protein-level localization within germ cells","Functional requirement not yet tested genetically"]},{"year":2012,"claim":"Linked TSSK1B to a defined developmental requirement, showing the kinase is needed for normal spermiogenesis and is functionally constrained yet partly divergent from TSSK2.","evidence":"Mouse Tssk1/Tssk2 knockout phenotyping combined with selection analysis of primate orthologues","pmids":["23258646"],"confidence":"Medium","gaps":["Phenotype is from combined Tssk1/Tssk2 deletion, not TSSK1B alone","Physiological substrates in spermatids unidentified","Differential function relative to TSSK2 not mechanistically defined"]},{"year":2021,"claim":"Provided basic biochemical characterization, confirming TSSK1B is a cytoplasmic hydrophilic kinase with an intact S_TKc catalytic domain that can be produced as recombinant protein.","evidence":"cDNA cloning, bioinformatics, prokaryotic recombinant expression, and RT-PCR profiling in tree shrew","pmids":["33765466"],"confidence":"Low","gaps":["Localization inferred from bioinformatics rather than imaging","No demonstrated kinase activity on a defined substrate","Detection of mRNA outside testis not validated at protein level"]},{"year":2023,"claim":"Identified an epigenetic mechanism controlling TSSK1B expression, tying promoter hypermethylation to its loss in sterile hybrid testis.","evidence":"RT-qPCR, IHC, and bisulfite-sequencing PCR in yak versus cattle-yak testis","pmids":["36670860"],"confidence":"Medium","gaps":["Causal link between methylation and sterility not directly tested","Regulatory factors driving promoter methylation unknown"]},{"year":2023,"claim":"Advanced TSSK1B as a male contraceptive target by computationally ranking active-site inhibitors, framing it as a druggable kinase.","evidence":"Multisite λ-dynamics free energy calculations and QSAR modeling (computational)","pmids":["36906820"],"confidence":"Low","gaps":["Purely computational with no experimental binding or inhibition validation","No structural model confirmed against the predicted active site"]},{"year":2024,"claim":"Defined a non-testicular signaling role, showing TSSK1B suppresses YAP through dual phosphorylation events and links upstream LKB1 to Hippo pathway control of proliferation.","evidence":"In vitro phosphorylation assays, co-IP, phosphosite mutagenesis, YAP-TEAD reporter assays, and proliferation/transformation assays","pmids":["38245531"],"confidence":"Medium","gaps":["Performed in cell models, not in vivo tumor context","Mechanism of LATS1/2 activation by TSSK1B not resolved","Relationship between testicular and YAP-regulatory functions unclear"]},{"year":null,"claim":"How TSSK1B's role in spermiogenesis mechanistically connects to its YAP/Hippo-regulatory activity, and what its direct germ-cell substrates are, remains unresolved.","evidence":"No discovery in the corpus bridges the spermatid and Hippo-pathway functions or identifies germ-cell phosphorylation substrates","pmids":[],"confidence":"Low","gaps":["No identified physiological substrate in spermatids","TSSK1B-specific (non-redundant with TSSK2) knockout phenotype undefined","No structural data on the kinase"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[2]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[2,5]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[5]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[2]},{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[1]}],"complexes":[],"partners":["YAP1","LATS1","LATS2","LKB1","TSSK2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9BXA7","full_name":"Testis-specific serine/threonine-protein kinase 1","aliases":["Serine/threonine-protein kinase 22A"],"length_aa":367,"mass_kda":41.6,"function":"Testis-specific serine/threonine-protein kinase required during spermatid development. Phosphorylates 'Ser-288' of TSKS. Involved in the late stages of spermatogenesis, during the reconstruction of the cytoplasm. During spermatogenesis, required for the transformation of a ring-shaped structure around the base of the flagellum originating from the chromatoid body","subcellular_location":"Cytoplasm; Cytoplasmic vesicle, secretory vesicle, acrosome; Cell projection, cilium, flagellum","url":"https://www.uniprot.org/uniprotkb/Q9BXA7/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TSSK1B","classification":"Not Classified","n_dependent_lines":6,"n_total_lines":1208,"dependency_fraction":0.004966887417218543},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/TSSK1B","total_profiled":1310},"omim":[{"mim_id":"610709","title":"TESTIS-SPECIFIC SERINE/THREONINE KINASE 1; TSSK1","url":"https://www.omim.org/entry/610709"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nuclear bodies","reliability":"Approved"},{"location":"Principal piece","reliability":"Approved"},{"location":"Centrosome","reliability":"Additional"},{"location":"Basal body","reliability":"Additional"},{"location":"Perinuclear theca","reliability":"Additional"},{"location":"End piece","reliability":"Additional"},{"location":"Annulus","reliability":"Additional"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in single","driving_tissues":[{"tissue":"testis","ntpm":51.7}],"url":"https://www.proteinatlas.org/search/TSSK1B"},"hgnc":{"alias_symbol":["SPOGA4","FKSG81"],"prev_symbol":["STK22D","TSSK1"]},"alphafold":{"accession":"Q9BXA7","domains":[{"cath_id":"3.30.200.20","chopping":"2-90","consensus_level":"high","plddt":94.3664,"start":2,"end":90},{"cath_id":"1.10.510.10","chopping":"95-271","consensus_level":"high","plddt":96.1969,"start":95,"end":271}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BXA7","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BXA7-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BXA7-F1-predicted_aligned_error_v6.png","plddt_mean":80.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TSSK1B","jax_strain_url":"https://www.jax.org/strain/search?query=TSSK1B"},"sequence":{"accession":"Q9BXA7","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9BXA7.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9BXA7/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BXA7"}},"corpus_meta":[{"pmid":"27865410","id":"PMC_27865410","title":"Comparative analysis of testis transcriptomes associated with male infertility in cattleyak.","date":"2016","source":"Theriogenology","url":"https://pubmed.ncbi.nlm.nih.gov/27865410","citation_count":68,"is_preprint":false},{"pmid":"11597141","id":"PMC_11597141","title":"Cloning and chromosomal localization of a gene encoding a novel serine/threonine kinase belonging to the subfamily of testis-specific kinases.","date":"2001","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/11597141","citation_count":34,"is_preprint":false},{"pmid":"35207567","id":"PMC_35207567","title":"Omics and Male Infertility: Highlighting the Application of Transcriptomic Data.","date":"2022","source":"Life (Basel, Switzerland)","url":"https://pubmed.ncbi.nlm.nih.gov/35207567","citation_count":30,"is_preprint":false},{"pmid":"35173218","id":"PMC_35173218","title":"Using publicly available transcriptomic data to identify mechanistic and diagnostic biomarkers in azoospermia and overall male infertility.","date":"2022","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/35173218","citation_count":24,"is_preprint":false},{"pmid":"23258646","id":"PMC_23258646","title":"Evolution of testis-specific kinases TSSK1B and TSSK2 in primates.","date":"2012","source":"Andrology","url":"https://pubmed.ncbi.nlm.nih.gov/23258646","citation_count":15,"is_preprint":false},{"pmid":"38245531","id":"PMC_38245531","title":"The LKB1-TSSK1B axis controls YAP phosphorylation to regulate the Hippo-YAP pathway.","date":"2024","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/38245531","citation_count":13,"is_preprint":false},{"pmid":"38847481","id":"PMC_38847481","title":"Male infertility and perfluoroalkyl and poly-fluoroalkyl substances: evidence for alterations in phosphorylation of proteins and fertility-related functional attributes in bull spermatozoa†.","date":"2024","source":"Biology of reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/38847481","citation_count":8,"is_preprint":false},{"pmid":"36670860","id":"PMC_36670860","title":"The Biological Characteristics and Differential Expression Patterns of TSSK1B Gene in Yak and Its Infertile Hybrid Offspring.","date":"2023","source":"Animals : an open access journal from MDPI","url":"https://pubmed.ncbi.nlm.nih.gov/36670860","citation_count":7,"is_preprint":false},{"pmid":"30733657","id":"PMC_30733657","title":"Interstitial Deletion of 5q22.2q23.1 Including APC and TSSK1B in a Patient with Adenomatous Polyposis and Asthenoteratozoospermia.","date":"2018","source":"Molecular syndromology","url":"https://pubmed.ncbi.nlm.nih.gov/30733657","citation_count":7,"is_preprint":false},{"pmid":"35485285","id":"PMC_35485285","title":"Role of testis‑specific serine kinase 1B in undiagnosed male infertility.","date":"2022","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/35485285","citation_count":6,"is_preprint":false},{"pmid":"33765466","id":"PMC_33765466","title":"cDNA cloning, expression and bioinformatical analysis of Tssk genes in tree shrews.","date":"2021","source":"Computational biology and chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/33765466","citation_count":5,"is_preprint":false},{"pmid":"37151112","id":"PMC_37151112","title":"Integrated testis transcriptome and whole genome analysis of sexual maturity in Large White and Tongcheng pigs.","date":"2023","source":"Reproduction in domestic animals = Zuchthygiene","url":"https://pubmed.ncbi.nlm.nih.gov/37151112","citation_count":4,"is_preprint":false},{"pmid":"28596815","id":"PMC_28596815","title":"Next-generation sequencing traces human induced pluripotent stem cell lines clonally generated from heterogeneous cancer tissue.","date":"2017","source":"World journal of stem cells","url":"https://pubmed.ncbi.nlm.nih.gov/28596815","citation_count":3,"is_preprint":false},{"pmid":"36906820","id":"PMC_36906820","title":"QSAR via multisite λ-dynamics in the orphaned TSSK1B kinase.","date":"2023","source":"Protein science : a publication of the Protein Society","url":"https://pubmed.ncbi.nlm.nih.gov/36906820","citation_count":2,"is_preprint":false},{"pmid":"39331630","id":"PMC_39331630","title":"Whole-genome Sequencing Association Analysis of Quantitative Platelet Traits in A Large Cohort of β-thalassemia.","date":"2025","source":"Genomics, proteomics & bioinformatics","url":"https://pubmed.ncbi.nlm.nih.gov/39331630","citation_count":1,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10742,"output_tokens":1672,"usd":0.028653,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8485,"output_tokens":2275,"usd":0.04965,"stage2_stop_reason":"end_turn"},"total_usd":0.078303,"stage1_batch_id":"msgbatch_017qqVz33Ga63SCDwzb35XPb","stage2_batch_id":"msgbatch_01Scr2Ei9x4HJMiRGxwrmvLK","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2001,\n      \"finding\": \"TSSK1B (STK22D) encodes a novel testis-specific serine/threonine kinase of 268 amino acids, developmentally expressed in testicular germ cells and not present in brain, ovary, kidney, liver, or early embryonic cells; the human homologue is expressed exclusively in the testis. Chromosomal localization mapped to 1p34-p35 (human) and 4E1 (mouse) by FISH.\",\n      \"method\": \"RT-PCR cloning, northern blot analysis, fluorescence in situ hybridization (FISH)\",\n      \"journal\": \"Genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct cloning and northern blot characterization, single lab, two orthogonal methods (northern blot + FISH) establishing expression pattern and chromosomal localization\",\n      \"pmids\": [\"11597141\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"In primates, the kinase domains of TSSK1B and TSSK2 have evolved under negative (purifying) selection, indicating functional constraint to maintain kinase activity. The C-terminal domain of TSSK1B shows evidence of positive selection, suggesting TSSK1B and TSSK2 perform at least partly differential functions. TSSK1 and TSSK2 are present in elongating spermatids, and targeted deletion of mouse Tssk1/Tssk2 results in dysregulation of spermiogenesis.\",\n      \"method\": \"Evolutionary sequence analysis (selection analysis of primate orthologues), genetic deletion (mouse knockout)\",\n      \"journal\": \"Andrology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mouse KO with defined spermiogenesis phenotype combined with evolutionary analysis, single lab\",\n      \"pmids\": [\"23258646\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TSSK1B is a negative regulator of YAP in the Hippo pathway. Mechanistically: (1) an LKB1-TSSK1B axis directly phosphorylates YAP at Ser94, inhibiting YAP-TEAD complex formation and suppressing target gene expression; (2) a TSSK1B-LATS1/2 axis inhibits YAP via phosphorylation at Ser127. TSSK1B is a member of the CAMK superfamily and suppresses cellular proliferation and oncogenic transformation.\",\n      \"method\": \"Phosphorylation assays, co-immunoprecipitation, mutational analysis of phosphorylation sites, transcriptional reporter assays for YAP-TEAD targets, cell proliferation and transformation assays\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct phosphorylation site identification with functional readouts (complex formation, target gene expression, proliferation), single lab, multiple orthogonal methods\",\n      \"pmids\": [\"38245531\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TSSK1B protein localizes to spermatogenic cells in yak testis (confirmed by immunohistochemistry), is specifically expressed in testis, and shows near-absent expression in cattle-yak testis associated with hypermethylation of the TSSK1B promoter region, suggesting epigenetic regulation of its expression during spermatogenesis.\",\n      \"method\": \"RT-qPCR, immunohistochemistry (IHC), bisulfite-sequencing PCR (BSP) for promoter methylation analysis\",\n      \"journal\": \"Animals\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct localization by IHC and methylation mechanism identified by BSP, single lab, two orthogonal methods linking promoter methylation to reduced expression\",\n      \"pmids\": [\"36670860\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Multisite λ-dynamics (MSλD) computational approach was applied to TSSK1B as a validated target for male contraception, calculating relative binding free energies of 1296 inhibitors to the kinase active site and establishing a quantitative structure-activity relationship (QSAR) for inhibitor binding.\",\n      \"method\": \"Multisite λ-dynamics (MSλD) free energy calculations (computational)\",\n      \"journal\": \"Protein science\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — purely computational study, no experimental biochemical validation of TSSK1B inhibition or binding\",\n      \"pmids\": [\"36906820\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"In tree shrews, TSSK1B protein distributes in the cytoplasm, is a hydrophilic non-secretory protein with multiple serine/threonine phosphorylation sites, and contains the conserved S_TKc catalytic domain. Recombinant TSSK1B protein was successfully expressed in a prokaryotic system. Unlike other TSSK family members restricted to testis/sperm, small amounts of TSSK1B mRNA were detected in several tissues beyond testis and sperm.\",\n      \"method\": \"cDNA cloning, bioinformatics, prokaryotic recombinant protein expression, RT-PCR tissue expression profiling, subcellular localization prediction confirmed with expressed protein\",\n      \"journal\": \"Computational biology and chemistry\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — recombinant protein expression and basic characterization in a single lab; localization inferred from bioinformatics rather than live-cell imaging\",\n      \"pmids\": [\"33765466\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TSSK1B is a testis-specific serine/threonine kinase (CAMK superfamily) that is essential for spermiogenesis (mouse Tssk1/2 double-KO causes spermiogenic failure), localizes to elongating spermatids, and—outside the testis—functions as a negative regulator of the Hippo pathway effector YAP by directly phosphorylating YAP at Ser94 (blocking YAP-TEAD complex formation) and activating LATS1/2 to phosphorylate YAP at Ser127, with the LKB1-TSSK1B signaling axis upstream of both events.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TSSK1B is a testis-enriched serine/threonine kinase of the CAMK superfamily whose primary characterized role is in spermiogenesis, where it is expressed in elongating spermatids and is required for normal spermatid maturation [#0, #1]. Targeted deletion of mouse Tssk1/Tssk2 dysregulates spermiogenesis, and evolutionary analysis shows the kinase domain is held under purifying selection while the C-terminus diverges, consistent with conserved catalytic function alongside functions distinct from its paralog TSSK2 [#1]. Its testis-restricted expression is set epigenetically: promoter hypermethylation correlates with near-absent TSSK1B in sterile cattle-yak testis [#3]. Beyond the testis, TSSK1B acts as a negative regulator of the Hippo pathway effector YAP through two converging routes—an LKB1-TSSK1B axis that directly phosphorylates YAP at Ser94 to block YAP-TEAD complex formation and target gene transcription, and a TSSK1B-LATS1/2 axis that drives inhibitory YAP phosphorylation at Ser127—thereby suppressing proliferation and oncogenic transformation [#2].\",\n  \"teleology\": [\n    {\n      \"year\": 2001,\n      \"claim\": \"Established the existence and tissue identity of TSSK1B, defining it as a testis-specific serine/threonine kinase rather than a broadly expressed enzyme.\",\n      \"evidence\": \"RT-PCR cloning, northern blot, and FISH mapping in human and mouse germ cells\",\n      \"pmids\": [\"11597141\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No substrate or catalytic mechanism identified\", \"No protein-level localization within germ cells\", \"Functional requirement not yet tested genetically\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Linked TSSK1B to a defined developmental requirement, showing the kinase is needed for normal spermiogenesis and is functionally constrained yet partly divergent from TSSK2.\",\n      \"evidence\": \"Mouse Tssk1/Tssk2 knockout phenotyping combined with selection analysis of primate orthologues\",\n      \"pmids\": [\"23258646\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Phenotype is from combined Tssk1/Tssk2 deletion, not TSSK1B alone\", \"Physiological substrates in spermatids unidentified\", \"Differential function relative to TSSK2 not mechanistically defined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Provided basic biochemical characterization, confirming TSSK1B is a cytoplasmic hydrophilic kinase with an intact S_TKc catalytic domain that can be produced as recombinant protein.\",\n      \"evidence\": \"cDNA cloning, bioinformatics, prokaryotic recombinant expression, and RT-PCR profiling in tree shrew\",\n      \"pmids\": [\"33765466\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Localization inferred from bioinformatics rather than imaging\", \"No demonstrated kinase activity on a defined substrate\", \"Detection of mRNA outside testis not validated at protein level\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified an epigenetic mechanism controlling TSSK1B expression, tying promoter hypermethylation to its loss in sterile hybrid testis.\",\n      \"evidence\": \"RT-qPCR, IHC, and bisulfite-sequencing PCR in yak versus cattle-yak testis\",\n      \"pmids\": [\"36670860\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal link between methylation and sterility not directly tested\", \"Regulatory factors driving promoter methylation unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Advanced TSSK1B as a male contraceptive target by computationally ranking active-site inhibitors, framing it as a druggable kinase.\",\n      \"evidence\": \"Multisite \\u03bb-dynamics free energy calculations and QSAR modeling (computational)\",\n      \"pmids\": [\"36906820\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Purely computational with no experimental binding or inhibition validation\", \"No structural model confirmed against the predicted active site\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defined a non-testicular signaling role, showing TSSK1B suppresses YAP through dual phosphorylation events and links upstream LKB1 to Hippo pathway control of proliferation.\",\n      \"evidence\": \"In vitro phosphorylation assays, co-IP, phosphosite mutagenesis, YAP-TEAD reporter assays, and proliferation/transformation assays\",\n      \"pmids\": [\"38245531\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Performed in cell models, not in vivo tumor context\", \"Mechanism of LATS1/2 activation by TSSK1B not resolved\", \"Relationship between testicular and YAP-regulatory functions unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How TSSK1B's role in spermiogenesis mechanistically connects to its YAP/Hippo-regulatory activity, and what its direct germ-cell substrates are, remains unresolved.\",\n      \"evidence\": \"No discovery in the corpus bridges the spermatid and Hippo-pathway functions or identifies germ-cell phosphorylation substrates\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No identified physiological substrate in spermatids\", \"TSSK1B-specific (non-redundant with TSSK2) knockout phenotype undefined\", \"No structural data on the kinase\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [2]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [2, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2]},\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"YAP1\", \"LATS1\", \"LATS2\", \"LKB1\", \"TSSK2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":4,"faith_pct":100.0}}