Figure 2.

Inhibition of nuclear DNA replication by removal of PP2A from egg cytosol. Egg cytosol was depleted with either mAb 6F9 or rat IgG. C subunit was added to PP2A-depleted extract at a final concentration of 0.13 μg/μl, which corresponds approximately to the endogenous concentration of PP2A in the extract. Purified membranes, [α-³²P]dCTP, and demembranated sperm were added to a concentration of 4,000 sperm per μl. Reactions were stopped at 60, 120, and 240 min, and the DNA were analyzed on a 0.8% agarose gel (A) and quantitated with a Molecular Dynamics PhosphorImager (B). (C) After adding membranes and a 90-min period, the nuclei were analyzed by fluorescence microscopy by using Hoechst dye staining to visualize DNA. Open circles, 6F9 depletion; closed circles, 6F9 depletion plus C subunit; open squares, mock (rat IgG) depletion.