CATSPER1 (cation channel sperm associated 1) encodes a pore-forming subunit of the CatSper complex, a sperm-specific voltage-gated calcium channel essential for male fertility 1. The protein is primarily localized to the principal piece of the sperm flagellum and functions in calcium-dependent physiological responses required for successful fertilization, including sperm hyperactivation, capacitation, and motility 21. CATSPER1 expression is positively correlated with progressive motility, hyperactivated motility, and calcium responsiveness to progesterone, with reduced expression observed in asthenozoospermic men compared to normozoospermic controls 13. The gene is transcriptionally regulated by CREB1 and CREMτ transcription factors, with Sox5 and Sox9 also contributing to its regulation during spermatogenesis 45. CATSPER1 transcript levels in ejaculated spermatozoa correlate with sperm quality parameters, fertilization rates, and embryo development in ICSI procedures 36. Genetic polymorphisms in CATSPER1 have been associated with idiopathic azoospermia and oligospermia risk, highlighting its clinical relevance in male infertility 7. The channel's critical role in sperm function makes it a potential target for both infertility diagnosis and contraceptive development.