Comparative Genomics Analysis of Cation Channel Sperm-associated Proteins (CATSPERs)Associated with Sperm Motility in Livestock

The CATSPER gene family encodes essential ion channels that govern sperm motility and male fertility across mammalian species.This study presents a comprehensive evolutionary and functional analysis of CATSPER genes (CATSPER 1-4) in cattle, sheep and pigs, integrating comparative genomics, analysis of selection pressure, and structural characterization.Using maximum likelihood models (M1a/M2a and M7/M8), strong signatures of positive selection in all four CATSPER genes were identified (2=38.27-67.45,P<0.05), with Bayesian Empirical Bayes analysis revealing 11-17 positively selected sites per gene.These adaptive mutations were predominantly located in ion transport domains (Pfam) and showed lineage-specific patterns, particularly in primate CATSPER2/4.Concurrently, purifying selection maintained critical functional regions, as evidenced by high conservation scores (ConSurf) and structural integrity (ERRAT>74.32).Phylogenetic reconstruction demonstrated deep conservation of CATSPER proteins across Artiodactyla, with gene duplication events observed in rodent lineages.Functional characterization revealed 4-6 transmembrane domains per protein and identified key post-translational modification sites (phosphorylation, glycosylation).Protein-protein interaction networks (STRING) implicated CATSPER in a reproductive complex with AKAP3, SPAG6/16, and CABYR, regulating flagellar calcium signaling.Notably, nuclear hormone receptor binding motifs were predicted in promoter regions, suggesting endocrine regulation of CATSPER expression.These findings provide evolutionary and mechanistic insights into CATSPER-mediated fertility, highlighting the followings: 1) Adaptive evolution in ion transport domains correlates with speciesspecific sperm motility requirements, 2) Structural conservation maintains core channel function despite lineage-specific adaptations, and 3) Protein interaction networks integrate CATSPER into broader sperm motility pathways.The study establishes a framework for targeting CATSPER variants in livestock breeding programs and informs comparative models of male fertility across mammals.