Affinage

CATSPER2

Cation channel sperm-associated protein 2 · UniProt Q96P56

Length
530 aa
Mass
62.0 kDa
Annotated
2026-04-28
11 papers in source corpus 5 papers cited in narrative 5 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

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).

Mechanistic history

Synthesis pass · year-by-year structured walk · 5 steps
  1. 2003 High

    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

    PMID:14657366

    Open questions at the time
    • 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
  2. 2005 High

    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

    PMID:16036917

    Open questions at the time
    • 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
  3. 2011 Medium

    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

    PMID:22002435

    Open questions at the time
    • Knockdown efficiency and off-target effects not independently validated
    • No electrophysiological confirmation of current loss
    • Single laboratory study
  4. 2019 High

    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

    PMID:30629171

    Open questions at the time
    • 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
  5. 2022 Medium

    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

    PMID:36345591

    Open questions at the time
    • 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

Open questions

Synthesis pass · forward-looking unresolved questions
  • 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.
  • 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

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005215 transporter activity 2
Localization
GO:0005886 plasma membrane 2
Pathway
R-HSA-1474165 Reproduction 3
Partners
CATSPER1
Complex memberships
CatSper channel complex

Evidence

Reading pass · 5 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2003 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. Gene knockout (CatSper2-/- mice), motility assays, viscosity challenge, acrosome reaction assay, protein tyrosine phosphorylation analysis Proceedings of the National Academy of Sciences of the United States of America High 14657366
2005 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. Fluorescence Ca2+ imaging, electrophysiology (depolarization-evoked Ca2+ entry), Western blot for protein co-dependency, PKA inhibitor H89 rescue, beat frequency analysis, procaine rescue experiment The Journal of biological chemistry High 16036917
2019 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. 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 Human reproduction (Oxford, England) High 30629171
2011 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. In vivo electroporation/rete testis microinjection siRNA knockdown, CASA motility analysis, intracellular Ca2+ measurement, in vitro fertilization assay Asian journal of andrology Medium 22002435
2022 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. Luciferase reporter assay, site-directed mutagenesis of CTCF/CRE sites, ChIP assay, WGBS methylation analysis, ChIP-seq data analysis FEBS open bio Medium 36345591

Source papers

Stage 0 corpus · 11 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2003 Hyperactivated sperm motility driven by CatSper2 is required for fertilization. Proceedings of the National Academy of Sciences of the United States of America 283 14657366
2003 CATSPER2, a human autosomal nonsyndromic male infertility gene. European journal of human genetics : EJHG 157 12825070
2005 Identical phenotypes of CatSper1 and CatSper2 null sperm. The Journal of biological chemistry 143 16036917
2019 A novel copy number variation in CATSPER2 causes idiopathic male infertility with normal semen parameters. Human reproduction (Oxford, England) 65 30629171
2022 Frequency of the STRC-CATSPER2 deletion in STRC-associated hearing loss patients. Scientific reports 24 35022556
2019 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. Molecular reproduction and development 15 31041823
2011 Regulation of fertilization in male rats by CatSper2 knockdown. Asian journal of andrology 8 22002435
2022 Characterization of the promoter region of the murine Catsper2 gene. FEBS open bio 4 36345591
2017 Expression Profiling and Identification of Novel SNPs in CatSper2 Gene and Their Influence on Sperm Motility Parameters in Bovines. Animal biotechnology 2 28358238
2025 N-acetylcysteine Improved Expression of FSHR, LHCGR, Catsper-1, Catsper-2, and SF-1 Genes in Testis of Rats with Varicocele. Reproductive sciences (Thousand Oaks, Calif.) 0 41339973
2020 Effect of experimental hyperthyroidism on CatSper1 and CatSper2 genes expression in the seminiferous tubules of BALB/c mice: An experimental study. International journal of reproductive biomedicine 0 32923926