Protein tyrosine phosphorylation in sperm during gamete interaction in the mouse: the influence of glucose.

A key intracellular event during capacitation is protein tyrosine phosphorylation, but its involvement during sperm interaction with the oocyte has not been investigated. Glucose is necessary to achieve fertilization and thus may have an influence on sperm protein tyrosine phosphorylation. The objectives of this study were to 1) visualize protein tyrosine phosphorylation patterns in sperm during capacitation and interaction with the oocyte and 2) determine the influence of glucose. Protein tyrosine phosphorylation was investigated by Western analysis and immunofluorescence. Protein tyrosine phosphorylation was increased during capacitation, and immunofluorescence revealed that zona binding and gamete fusion were correlated with an increase in tyrosine phosphorylation of proteins in the midpiece. During capacitation, the absence of glucose led to a delay in the appearance of protein tyrosine phosphorylation. Following binding to the zona pellucida and the oolemma, tyrosine phosphorylation in the flagellum was also delayed in the absence of glucose and resulted in a significant inhibition of the midpiece phosphorylation. The correlation between successful gamete fusion and the tyrosine phosphorylation of midpiece proteins suggests that the effect of glucose on sperm-oocyte interaction is mediated through regulation of protein tyrosine phosphorylation in a specific area of the fertilizing sperm.