The sperm-derived oocyte activating factor, phospholipase C zeta (PLC zeta), is the only PLC isoform reported in cattle. The objectives were to (1) localize PLC zeta in fresh and capacitated bovine sperm and (2) investigate the activation of PLC zeta during bull sperm capacitation and contributions of PLC activity to this process. We confirmed interaction of testis-specific isoform of Na/K-ATPase (ATP1A4) with PLC zeta (immunolocalization and immunoprecipitation) and tyrosine phosphorylation (immunoprecipitation) of PLC zeta (a post-translational protein modification commonly involved in activation of PLC in somatic cells) during capacitation. Furthermore, incubation of sperm under capacitating conditions upregulated PLC-mediated hyperactivated motility, tyrosine phosphoprotein content, acrosome reaction, and F-actin formation (flow cytometry), implying that PLC activity is enhanced during capacitation and contributing to these capacitation processes. In conclusion, we inferred that PLC zeta is activated during capacitation by tyrosine phosphorylation through a mechanism involving ATP1A4, contributing to capacitation-associated biochemical events.
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