In G₂,there are typically high levels of the mitotic cyclin.Why is cdc2 not active during G₂ if the mitotic cyclin is present? A)Cdc2 is also regulated by phosphorylation. B)Cdc2 does not bind to the mitotic cyclin. C)Cdc2 requires ubiquitination to be activated. D)Cdc2 also has to bind to cohesin to be activated.

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Quizplus · Accepted Answer

Cdc2, also known as CDK1, is regulated by phosphorylation on two key residues: threonine-161 (T161) and tyrosine-15 (Y15). When Y15 is phosphorylated, Cdc2 is inactivated and cannot bind to cyclin. Even if the mitotic cyclin is present, Cdc2 will not be activated unless Y15 is dephosphorylated. Therefore, the presence of mitotic cyclin alone is not enough to activate Cdc2.

In G2,there Are Typically High Levels of the Mitotic Cyclin

In G₂,there Are Typically High Levels of the Mitotic Cyclin