FIGURE 3.

Calcineurin participates in acrosomal exocytosis. A, a post nuclear extract from rat brain (1 μg of proteins, brain) or human sperm (10⁶ cells, sperm) were resolved in 12.5% gels, transferred to nitrocellulose membranes, and probed with an anti-calcineurin antibody. The molecular mass standard is indicated on the left. B, permeabilized spermatozoa were treated at 37 °C for 10 min with 2 μm CsA, 1 μm FK 506, 67 nm anti-calcineurin antibody (antiCaN), or 100 μm VIVIT for 10 min at 37 °C. AE was then initiated by adding 10 μm free Ca²⁺, and the incubation continued for an additional 15 min (black bars). Controls include (gray bars) background AE in the absence of any stimulation (control) and AE stimulated by 10 μm free Ca²⁺. The sperm were fixed, and AE was measured. The percentage of reacted sperm was normalized as described under “Experimental Procedures.” The data represent the means ± S.E. of at least three independent experiments. The asterisks indicate significant differences from 100 (one-way ANOVA and 95% confidence interval for each condition).