Which of the following purified protein complexes would successfully drive the oocyte into M phase?

The successful transition of oocytes into M phase, or mitosis, relies on the activity of M-Cdk, which is a cyclin-dependent kinase activated by the binding of cyclin proteins. For M-Cdk to effectively promote the initiation of mitosis, it needs to be in a fully activated form.

In this scenario, the presence of both Wee1 and Cdc25 along with purified M-Cdk/cyclin is crucial. Wee1 is a kinase that phosphorylates M-Cdk, inhibiting its activity, while Cdc25 is a phosphatase that removes these inhibitory phosphate groups, thereby activating M-Cdk. The combination of these enzymes creates a regulatory environment where the inhibitory effects of Wee1 can be counteracted by Cdc25, allowing for the activation of M-Cdk and promoting the entry into M phase.

By including both Wee1 and Cdc25, this purified protein complex ensures that the balance between activation and inhibition of M-Cdk is correctly managed, allowing full activation in the context needed for the oocyte to progress into mitosis. This intricate regulation showcases the importance of multiple factors in controlling key transitions in the cell cycle. The other choices would not provide the necessary conditions to achieve this.