Figure 5.

The in vitro degradation of cyclin A, cyclin B, Xenopus geminin H, and S. pombe Cut2p involves the function of the “cyclin-selective Ubc” UbcH10. (A) HeLa G1 cell extracts were supplemented with buffer, 2.5 μM purified recombinant wild-type UbcH10 (-WT), or 2.5 μM purified recombinant dominant negative UbcH10 (-DN) and assayed for destruction activity toward radiolabeled cyclin A, cyclin B, Xenopus geminin H, and S. pombe Cut2p as described in Figure 1. (B) As a control, G1 extracts were supplemented with either 2.5 μM wild-type human Ubc3/CDC34 or 2.5 μM dominant negative human Ubc3/CDC34, and degradation of cyclin B was monitored.