{"gene":"CATSPER2","run_date":"2026-04-28T17:28:52","timeline":{"discoveries":[{"year":2003,"finding":"CatSper2 is required for sperm hyperactivated motility; CatSper2-null males are completely infertile despite normal sperm production, forward velocity, capacitation-associated tyrosine phosphorylation, and acrosome reaction. The defect is specifically failure to generate hyperactivated motility needed to penetrate the egg extracellular matrix, demonstrated by loss of forward swimming in high-viscosity medium.","method":"Gene knockout (CatSper2-/- mice), motility assays, viscosity challenge, acrosome reaction assay, protein tyrosine phosphorylation analysis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — clean KO mouse with multiple defined phenotypic readouts, replicated by subsequent studies","pmids":["14657366"],"is_preprint":false},{"year":2005,"finding":"CatSper2 is required for depolarization-evoked Ca2+ entry into sperm; CatSper2-null sperm lack this Ca2+ influx, which underlies failure of hyperactivation. CatSper1 and CatSper2 proteins are co-dependently expressed: CatSper1-null sperm lack CatSper2 protein and CatSper2-null sperm lack CatSper1 protein, despite normal transcript levels, indicating post-transcriptional/post-translational co-stability. CatSper2 is also required for PKA-mediated tonic control of resting cAMP content, as H89 normalized elevated beat frequency in null sperm.","method":"Fluorescence Ca2+ imaging, electrophysiology (depolarization-evoked Ca2+ entry), Western blot for protein co-dependency, PKA inhibitor H89 rescue, beat frequency analysis, procaine rescue experiment","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal methods (Ca2+ imaging, pharmacological rescue, Western blot protein co-dependency) in a single rigorous study","pmids":["16036917"],"is_preprint":false},{"year":2019,"finding":"A copy number variation disrupting CATSPER2 in a human patient abolishes CATSPER current, impairs sperm hyperactivation, prevents progesterone-evoked Ca2+ influx and monovalent current potentiation, and blocks progesterone-induced acrosome reaction and penetration ability enhancement, confirming CATSPER2 is essential for the progesterone response pathway in human sperm.","method":"Whole-cell patch-clamp (CATSPER current, KSPER current), single-sperm Ca2+ imaging, CASA motility analysis, methylcellulose penetration assay, chlortetracycline acrosome reaction staining, Western blot, whole-genome sequencing, TaqMan CNV assay","journal":"Human reproduction (Oxford, England)","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal methods including electrophysiology, Ca2+ imaging, and functional assays in a natural human loss-of-function model","pmids":["30629171"],"is_preprint":false},{"year":2011,"finding":"Knockdown of CatSper2 in rat testis via rete testis microinjection of siRNA plasmid reduces hyperactivation rate, in vitro fertilization rate, migration motility in viscoelastic solution, and intracellular Ca2+ peak, confirming CatSper2's role in Ca2+-dependent hyperactivation and fertilization in vivo.","method":"In vivo electroporation/rete testis microinjection siRNA knockdown, CASA motility analysis, intracellular Ca2+ measurement, in vitro fertilization assay","journal":"Asian journal of andrology","confidence":"Medium","confidence_rationale":"Tier 2 — KD with defined cellular phenotype using multiple readouts, single lab","pmids":["22002435"],"is_preprint":false},{"year":2022,"finding":"The murine Catsper2 promoter is regulated by transcription factors CREMτ and CTCF, which bind to the minimal promoter region (-54/+189 relative to TSS); mutation of CTCF binding sites and deletion of the CRE site reduce promoter activity. The gene body carries histone marks H3K4me3 and H3K36me3 indicating active transcription, and the CpG island is unmethylated.","method":"Luciferase reporter assay, site-directed mutagenesis of CTCF/CRE sites, ChIP assay, WGBS methylation analysis, ChIP-seq data analysis","journal":"FEBS open bio","confidence":"Medium","confidence_rationale":"Tier 2 — functional mutagenesis and ChIP confirmation, single lab, moderate evidence","pmids":["36345591"],"is_preprint":false}],"current_model":"CATSPER2 is a sperm-specific voltage-gated cation channel subunit that mediates depolarization-evoked Ca2+ entry into the sperm flagellum; it is essential for hyperactivated motility and progesterone-evoked Ca2+ signaling, co-stabilizes with CatSper1 protein post-translationally, and its loss abolishes fertilization capacity without affecting forward velocity, capacitation, or acrosome reaction."},"narrative":{"teleology":[{"year":2003,"claim":"Establishing that CatSper2 is specifically required for hyperactivated motility — not forward swimming, capacitation, or acrosome reaction — resolved that CatSper channels govern a discrete motility program essential for egg penetration.","evidence":"CatSper2 knockout mice with motility, viscosity challenge, acrosome reaction, and tyrosine phosphorylation assays","pmids":["14657366"],"confidence":"High","gaps":["Ionic mechanism (Ca2+ entry vs. other ion flux) not directly measured","Whether CatSper1 and CatSper2 are co-dependent at the protein level was unknown","How CatSper2 loss leads specifically to hyperactivation failure was not resolved"]},{"year":2005,"claim":"Demonstrating that CatSper2 is required for depolarization-evoked Ca2+ influx and that CatSper1 and CatSper2 proteins are co-dependent established the channel as a heteromeric complex and defined the ionic basis of the hyperactivation defect.","evidence":"Ca2+ imaging, electrophysiology, Western blot for reciprocal protein co-dependency, H89 pharmacological rescue in CatSper-null sperm","pmids":["16036917"],"confidence":"High","gaps":["Whether human CATSPER2 functions identically was untested","The role of CatSper2 in progesterone signaling was unknown","Structural basis of CatSper1–CatSper2 co-stabilization not determined"]},{"year":2011,"claim":"In vivo knockdown of CatSper2 in rat testis independently confirmed its role in Ca2+-dependent hyperactivation and fertilization, extending findings beyond the mouse knockout.","evidence":"Rete testis microinjection of siRNA, CASA motility analysis, Ca2+ measurement, IVF assay in rat","pmids":["22002435"],"confidence":"Medium","gaps":["Knockdown efficiency and off-target effects not independently validated","No electrophysiological confirmation of current loss","Single laboratory study"]},{"year":2019,"claim":"A natural human CATSPER2 loss-of-function confirmed that it is required for the CatSper current, progesterone-evoked Ca2+ signaling, and acrosome reaction in human sperm, translating the mouse findings to human reproductive biology.","evidence":"Whole-cell patch-clamp, single-sperm Ca2+ imaging, CASA, penetration assay, acrosome staining, WGS/CNV genotyping in a CATSPER2-disrupted human patient","pmids":["30629171"],"confidence":"High","gaps":["Whether CATSPER2 disruption is a common cause of human male infertility is unquantified","Progesterone receptor–CatSper coupling mechanism not defined","No rescue experiment to confirm causality in human sperm"]},{"year":2022,"claim":"Identification of CREMτ and CTCF as regulators of the Catsper2 promoter provided the first transcriptional control mechanism for testis-specific CatSper2 expression.","evidence":"Luciferase reporter assays with site-directed mutagenesis, ChIP, WGBS methylation analysis in murine system","pmids":["36345591"],"confidence":"Medium","gaps":["Whether these transcription factors are sufficient or necessary in vivo is untested","Regulation in human CATSPER2 promoter not examined","How CREMτ/CTCF cooperate with other spermatogenic transcription factors is unknown"]},{"year":null,"claim":"The structural architecture of the CatSper heteromeric channel complex, the mechanism by which CatSper1–CatSper2 co-stabilization occurs, and the molecular link between progesterone receptor activation and CatSper channel gating remain unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No high-resolution structure of the CatSper complex","Mechanism of post-translational co-stabilization between subunits unknown","Identity of the progesterone-sensing component that activates CatSper is debated"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[1,2]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,2]}],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[0,2,3]}],"complexes":["CatSper channel complex"],"partners":["CATSPER1"],"other_free_text":[]},"mechanistic_narrative":"CATSPER2 is a sperm-specific cation channel subunit essential for Ca2+-dependent hyperactivated motility and fertilization. It forms a co-dependent complex with CatSper1, where loss of either subunit destabilizes the other at the protein level despite normal transcript abundance, and its absence abolishes depolarization-evoked Ca2+ entry into sperm [PMID:16036917]. CatSper2-null males are completely infertile due to failure of hyperactivated motility required for egg penetration, while forward velocity, capacitation, and acrosome reaction remain intact [PMID:14657366]. In human sperm, CATSPER2 loss-of-function eliminates the CatSper current and progesterone-evoked Ca2+ signaling, confirming its role as a core pore-forming subunit in the progesterone response pathway and establishing CATSPER2 disruption as a cause of male infertility [PMID:30629171]."},"prefetch_data":{"uniprot":{"accession":"Q96P56","full_name":"Cation channel sperm-associated protein 2","aliases":[],"length_aa":530,"mass_kda":62.0,"function":"Pore-forming subunit of the CatSper complex, a sperm-specific voltage-gated calcium channel, that plays a central role in calcium-dependent physiological responses essential for successful fertilization, such as sperm hyperactivation, acrosome reaction and chemotaxis towards the oocyte","subcellular_location":"Cell projection, cilium, flagellum membrane","url":"https://www.uniprot.org/uniprotkb/Q96P56/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CATSPER2","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/CATSPER2","total_profiled":1310},"omim":[{"mim_id":"617511","title":"CATION CHANNEL, SPERM-ASSOCIATED, AUXILIARY SUBUNIT ZETA; CATSPERZ","url":"https://www.omim.org/entry/617511"},{"mim_id":"613452","title":"CATION CHANNEL, SPERM-ASSOCIATED, AUXILIARY SUBUNIT GAMMA; CATSPERG","url":"https://www.omim.org/entry/613452"},{"mim_id":"611169","title":"CATION CHANNEL, SPERM-ASSOCIATED, AUXILIARY SUBUNIT BETA; CATSPERB","url":"https://www.omim.org/entry/611169"},{"mim_id":"611102","title":"DEAFNESS-INFERTILITY SYNDROME; DIS","url":"https://www.omim.org/entry/611102"},{"mim_id":"609121","title":"CATION CHANNEL, SPERM-ASSOCIATED, 4; CATSPER4","url":"https://www.omim.org/entry/609121"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"End piece","reliability":"Uncertain"},{"location":"Vesicles","reliability":"Additional"},{"location":"Plasma membrane","reliability":"Additional"},{"location":"Primary cilium","reliability":"Additional"},{"location":"Principal piece","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"retina","ntpm":21.4},{"tissue":"testis","ntpm":14.9}],"url":"https://www.proteinatlas.org/search/CATSPER2"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"Q96P56","domains":[{"cath_id":"-","chopping":"13-73","consensus_level":"medium","plddt":58.3144,"start":13,"end":73},{"cath_id":"1.20.120.350","chopping":"99-224","consensus_level":"high","plddt":86.264,"start":99,"end":224},{"cath_id":"1.10.287","chopping":"252-359","consensus_level":"medium","plddt":89.9099,"start":252,"end":359}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96P56","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96P56-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96P56-F1-predicted_aligned_error_v6.png","plddt_mean":69.25},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CATSPER2","jax_strain_url":"https://www.jax.org/strain/search?query=CATSPER2"},"sequence":{"accession":"Q96P56","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96P56.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96P56/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96P56"}},"corpus_meta":[{"pmid":"14657366","id":"PMC_14657366","title":"Hyperactivated sperm motility driven by CatSper2 is required for fertilization.","date":"2003","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/14657366","citation_count":283,"is_preprint":false},{"pmid":"12825070","id":"PMC_12825070","title":"CATSPER2, a human autosomal nonsyndromic male infertility gene.","date":"2003","source":"European journal of human genetics : EJHG","url":"https://pubmed.ncbi.nlm.nih.gov/12825070","citation_count":157,"is_preprint":false},{"pmid":"16036917","id":"PMC_16036917","title":"Identical phenotypes of CatSper1 and CatSper2 null sperm.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16036917","citation_count":143,"is_preprint":false},{"pmid":"30629171","id":"PMC_30629171","title":"A novel copy number variation in CATSPER2 causes idiopathic male infertility with normal semen parameters.","date":"2019","source":"Human reproduction (Oxford, England)","url":"https://pubmed.ncbi.nlm.nih.gov/30629171","citation_count":65,"is_preprint":false},{"pmid":"35022556","id":"PMC_35022556","title":"Frequency of the STRC-CATSPER2 deletion in STRC-associated hearing loss patients.","date":"2022","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/35022556","citation_count":24,"is_preprint":false},{"pmid":"31041823","id":"PMC_31041823","title":"The effect of clomiphene citrate and human chorionic gonadotropin on the expression of CatSper1, CatSper2, LHCGR, and SF1 genes, as well as the structural changes in testicular tissue of adult rats.","date":"2019","source":"Molecular reproduction and development","url":"https://pubmed.ncbi.nlm.nih.gov/31041823","citation_count":15,"is_preprint":false},{"pmid":"22002435","id":"PMC_22002435","title":"Regulation of fertilization in male rats by CatSper2 knockdown.","date":"2011","source":"Asian journal of andrology","url":"https://pubmed.ncbi.nlm.nih.gov/22002435","citation_count":8,"is_preprint":false},{"pmid":"36345591","id":"PMC_36345591","title":"Characterization of the promoter region of the murine Catsper2 gene.","date":"2022","source":"FEBS open bio","url":"https://pubmed.ncbi.nlm.nih.gov/36345591","citation_count":4,"is_preprint":false},{"pmid":"28358238","id":"PMC_28358238","title":"Expression Profiling and Identification of Novel SNPs in CatSper2 Gene and Their Influence on Sperm Motility Parameters in Bovines.","date":"2017","source":"Animal biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/28358238","citation_count":2,"is_preprint":false},{"pmid":"32923926","id":"PMC_32923926","title":"Effect of experimental hyperthyroidism on CatSper1 and CatSper2 genes expression in the seminiferous tubules of BALB/c mice: An experimental study.","date":"2020","source":"International journal of reproductive biomedicine","url":"https://pubmed.ncbi.nlm.nih.gov/32923926","citation_count":0,"is_preprint":false},{"pmid":"41339973","id":"PMC_41339973","title":"N-acetylcysteine Improved Expression of FSHR, LHCGR, Catsper-1, Catsper-2, and SF-1 Genes in Testis of Rats with Varicocele.","date":"2025","source":"Reproductive sciences (Thousand Oaks, Calif.)","url":"https://pubmed.ncbi.nlm.nih.gov/41339973","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7733,"output_tokens":1465,"usd":0.022587},"stage2":{"model":"claude-opus-4-6","input_tokens":4691,"output_tokens":1613,"usd":0.09567},"total_usd":0.118257,"stage1_batch_id":"msgbatch_011kfMfE81o6CTcyhVUqumuW","stage2_batch_id":"msgbatch_01DTputS6WNkH745x1nVSoBo","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2003,\n      \"finding\": \"CatSper2 is required for sperm hyperactivated motility; CatSper2-null males are completely infertile despite normal sperm production, forward velocity, capacitation-associated tyrosine phosphorylation, and acrosome reaction. The defect is specifically failure to generate hyperactivated motility needed to penetrate the egg extracellular matrix, demonstrated by loss of forward swimming in high-viscosity medium.\",\n      \"method\": \"Gene knockout (CatSper2-/- mice), motility assays, viscosity challenge, acrosome reaction assay, protein tyrosine phosphorylation analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO mouse with multiple defined phenotypic readouts, replicated by subsequent studies\",\n      \"pmids\": [\"14657366\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"CatSper2 is required for depolarization-evoked Ca2+ entry into sperm; CatSper2-null sperm lack this Ca2+ influx, which underlies failure of hyperactivation. CatSper1 and CatSper2 proteins are co-dependently expressed: CatSper1-null sperm lack CatSper2 protein and CatSper2-null sperm lack CatSper1 protein, despite normal transcript levels, indicating post-transcriptional/post-translational co-stability. CatSper2 is also required for PKA-mediated tonic control of resting cAMP content, as H89 normalized elevated beat frequency in null sperm.\",\n      \"method\": \"Fluorescence Ca2+ imaging, electrophysiology (depolarization-evoked Ca2+ entry), Western blot for protein co-dependency, PKA inhibitor H89 rescue, beat frequency analysis, procaine rescue experiment\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal methods (Ca2+ imaging, pharmacological rescue, Western blot protein co-dependency) in a single rigorous study\",\n      \"pmids\": [\"16036917\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"A copy number variation disrupting CATSPER2 in a human patient abolishes CATSPER current, impairs sperm hyperactivation, prevents progesterone-evoked Ca2+ influx and monovalent current potentiation, and blocks progesterone-induced acrosome reaction and penetration ability enhancement, confirming CATSPER2 is essential for the progesterone response pathway in human sperm.\",\n      \"method\": \"Whole-cell patch-clamp (CATSPER current, KSPER current), single-sperm Ca2+ imaging, CASA motility analysis, methylcellulose penetration assay, chlortetracycline acrosome reaction staining, Western blot, whole-genome sequencing, TaqMan CNV assay\",\n      \"journal\": \"Human reproduction (Oxford, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal methods including electrophysiology, Ca2+ imaging, and functional assays in a natural human loss-of-function model\",\n      \"pmids\": [\"30629171\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Knockdown of CatSper2 in rat testis via rete testis microinjection of siRNA plasmid reduces hyperactivation rate, in vitro fertilization rate, migration motility in viscoelastic solution, and intracellular Ca2+ peak, confirming CatSper2's role in Ca2+-dependent hyperactivation and fertilization in vivo.\",\n      \"method\": \"In vivo electroporation/rete testis microinjection siRNA knockdown, CASA motility analysis, intracellular Ca2+ measurement, in vitro fertilization assay\",\n      \"journal\": \"Asian journal of andrology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KD with defined cellular phenotype using multiple readouts, single lab\",\n      \"pmids\": [\"22002435\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The murine Catsper2 promoter is regulated by transcription factors CREMτ and CTCF, which bind to the minimal promoter region (-54/+189 relative to TSS); mutation of CTCF binding sites and deletion of the CRE site reduce promoter activity. The gene body carries histone marks H3K4me3 and H3K36me3 indicating active transcription, and the CpG island is unmethylated.\",\n      \"method\": \"Luciferase reporter assay, site-directed mutagenesis of CTCF/CRE sites, ChIP assay, WGBS methylation analysis, ChIP-seq data analysis\",\n      \"journal\": \"FEBS open bio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional mutagenesis and ChIP confirmation, single lab, moderate evidence\",\n      \"pmids\": [\"36345591\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CATSPER2 is a sperm-specific voltage-gated cation channel subunit that mediates depolarization-evoked Ca2+ entry into the sperm flagellum; it is essential for hyperactivated motility and progesterone-evoked Ca2+ signaling, co-stabilizes with CatSper1 protein post-translationally, and its loss abolishes fertilization capacity without affecting forward velocity, capacitation, or acrosome reaction.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"CATSPER2 is a sperm-specific cation channel subunit essential for Ca2+-dependent hyperactivated motility and fertilization. It forms a co-dependent complex with CatSper1, where loss of either subunit destabilizes the other at the protein level despite normal transcript abundance, and its absence abolishes depolarization-evoked Ca2+ entry into sperm [PMID:16036917]. CatSper2-null males are completely infertile due to failure of hyperactivated motility required for egg penetration, while forward velocity, capacitation, and acrosome reaction remain intact [PMID:14657366]. In human sperm, CATSPER2 loss-of-function eliminates the CatSper current and progesterone-evoked Ca2+ signaling, confirming its role as a core pore-forming subunit in the progesterone response pathway and establishing CATSPER2 disruption as a cause of male infertility [PMID:30629171].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Establishing that CatSper2 is specifically required for hyperactivated motility — not forward swimming, capacitation, or acrosome reaction — resolved that CatSper channels govern a discrete motility program essential for egg penetration.\",\n      \"evidence\": \"CatSper2 knockout mice with motility, viscosity challenge, acrosome reaction, and tyrosine phosphorylation assays\",\n      \"pmids\": [\"14657366\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Ionic mechanism (Ca2+ entry vs. other ion flux) not directly measured\",\n        \"Whether CatSper1 and CatSper2 are co-dependent at the protein level was unknown\",\n        \"How CatSper2 loss leads specifically to hyperactivation failure was not resolved\"\n      ]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Demonstrating that CatSper2 is required for depolarization-evoked Ca2+ influx and that CatSper1 and CatSper2 proteins are co-dependent established the channel as a heteromeric complex and defined the ionic basis of the hyperactivation defect.\",\n      \"evidence\": \"Ca2+ imaging, electrophysiology, Western blot for reciprocal protein co-dependency, H89 pharmacological rescue in CatSper-null sperm\",\n      \"pmids\": [\"16036917\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether human CATSPER2 functions identically was untested\",\n        \"The role of CatSper2 in progesterone signaling was unknown\",\n        \"Structural basis of CatSper1–CatSper2 co-stabilization not determined\"\n      ]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"In vivo knockdown of CatSper2 in rat testis independently confirmed its role in Ca2+-dependent hyperactivation and fertilization, extending findings beyond the mouse knockout.\",\n      \"evidence\": \"Rete testis microinjection of siRNA, CASA motility analysis, Ca2+ measurement, IVF assay in rat\",\n      \"pmids\": [\"22002435\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Knockdown efficiency and off-target effects not independently validated\",\n        \"No electrophysiological confirmation of current loss\",\n        \"Single laboratory study\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"A natural human CATSPER2 loss-of-function confirmed that it is required for the CatSper current, progesterone-evoked Ca2+ signaling, and acrosome reaction in human sperm, translating the mouse findings to human reproductive biology.\",\n      \"evidence\": \"Whole-cell patch-clamp, single-sperm Ca2+ imaging, CASA, penetration assay, acrosome staining, WGS/CNV genotyping in a CATSPER2-disrupted human patient\",\n      \"pmids\": [\"30629171\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether CATSPER2 disruption is a common cause of human male infertility is unquantified\",\n        \"Progesterone receptor–CatSper coupling mechanism not defined\",\n        \"No rescue experiment to confirm causality in human sperm\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identification of CREMτ and CTCF as regulators of the Catsper2 promoter provided the first transcriptional control mechanism for testis-specific CatSper2 expression.\",\n      \"evidence\": \"Luciferase reporter assays with site-directed mutagenesis, ChIP, WGBS methylation analysis in murine system\",\n      \"pmids\": [\"36345591\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether these transcription factors are sufficient or necessary in vivo is untested\",\n        \"Regulation in human CATSPER2 promoter not examined\",\n        \"How CREMτ/CTCF cooperate with other spermatogenic transcription factors is unknown\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The structural architecture of the CatSper heteromeric channel complex, the mechanism by which CatSper1–CatSper2 co-stabilization occurs, and the molecular link between progesterone receptor activation and CatSper channel gating remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No high-resolution structure of the CatSper complex\",\n        \"Mechanism of post-translational co-stabilization between subunits unknown\",\n        \"Identity of the progesterone-sensing component that activates CatSper is debated\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [1, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [0, 2, 3]}\n    ],\n    \"complexes\": [\"CatSper channel complex\"],\n    \"partners\": [\"CATSPER1\"],\n    \"other_free_text\": []\n  }\n}\n```"}