Fig. 5. Labeling patterns obtained with a polyclonal antibody raised against p48 peptide. (A) SDS-PAGE gel of S100 and corresponding western blots probed with anti-p48 and antiphosphotyrosine. In immunofluorescence assays anti-p48 labels the sperm plasma membrane uniformly in detergent-permeabilized sperm (B) but not in nonpermeabilized cells (C). In addition, the antibody labels organelles in the cell body that correspond in number, size and position to the membranous organelles (MOs). Bar, 10 µm.