ARRDC5 (arrestin domain containing 5) is a testis-enriched α-arrestin protein essential for mammalian spermatogenesis 1. Its primary function is to regulate sperm morphogenesis by controlling the attachment of the sperm head to the tail during spermiogenesis, the final differentiation phase 1. Mechanistically, ARRDC5 functions as a substrate for ZDHHC19-mediated S-palmitoylation at the plasma membrane of spermatids 2. ARRDC5 deficiency impairs spermatogenesis by affecting the localization and transport of SUN5 and NDC1, components of the head-tail coupling apparatus, likely through SEC22A-mediated vesicle trafficking 3. ARRDC5 knockout mice exhibit male-specific infertility characterized by sperm with abnormal morphology (backward head bending), reduced motility, and defective capacitation, preventing fertilization 13. The protein interacts with multiple V-type ATPase components, suggesting broader cellular functions 4. Clinically, ARRDC5 variants are associated with increased pancreatic cancer susceptibility in Jewish populations, with regulatory SNP rs2656937 located in ARRDC5 introns 5. These findings establish ARRDC5 as a critical regulator of spermatogenesis and a potential male contraceptive target 1.