Fig. 6. Comparison of the distribution of p48 and its phosphorylated form in detergent-permeabilized sperm by confocal fluorescence microscopy. Antiphosphotyrosine (green) labels the plasma membrane primarily at the leading edge of the lamellipod, whereas anti-p48 (red) labels the membrane uniformly. The green labeling in the cell body is due to recognition of fumarate reductase (see also Fig. 1) by antiphosphotyrosine. In this cell, anti-p48 failed to label the MOs. Bar, 10 µm.