Figure 6.

The steady-state levels of cyclin B–ubiquitin conjugates are lowered in OA-treated extracts. (A and B) The conversion of ¹²⁵I-labeled cyclin B 13–110 (Cyc B) into ubiquitin conjugates was followed in LLnL-treated extracts (50 μg/ml) induced to enter mitosis by addition of Δ90 in the absence (−OA) or presence (+OA) of 1 μM OA. Samples were taken at the indicated time points and analyzed by SDS-PAGE and phosphorimaging (B). The ubiquitination activity was expressed as the percentage of cyclin B converted into conjugates.