What does Cdk1 do in the cell cycle?

CDK1 promotes multiple biological processes that are critical for cell survival, including G2/M transition, checkpoint activation, DNA repair, and DNA replication as we propose. Its activities in these processes compromise the efficacy of chemotherapeutic drugs and may contribute to chemoresistance (a).

How does cyclin B Cdk1 regulate mitosis?

The accumulation of CDK1/cyclin B in the nucleus is facilitated by phosphorylation of cyclin B near its nuclear export signal, which thereby impedes nuclear exit. PLK1 contributes to mitotic entry and progression by facilitating these processes.

What is Cdk1 and Cdk2?

Cdk2 is thought to regulate entry into S phase, whereas Cdk1 controls the initiation of mitosis.

What does M CDK do in mitosis?

Mitotic CDKs are best known for their essential function in initiating mitosis, where they promote mitotic spindle formation, chromosome condensation, and the breakdown of the nuclear envelope (Nigg 2001; Miele 2004).

How does CDK1 become active?

CDK1 is activated by binding to B-type cyclins (mainly cyclin B1), which then phosphorylates substrates critical for entry into mitosis. Destruction of cyclin B1 provides a mechanism to rapidly inactivate CDK1 and allow the cell to exit mitosis (Fung and Poon, 2005). CDK1 is present throughout the cell cycle.

How is the activity of CDK1 regulated?

Given its essential role in cell cycle progression, Cdk1 is highly regulated. Most obviously, Cdk1 is regulated by its binding with its cyclin partners. Cyclin binding alters access to the active site of Cdk1, allowing for Cdk1 activity; furthermore, cyclins impart specificity to Cdk1 activity.

How does Cdk1 induce mitosis?

The Cdk1/cyclin B heterodimer induces mitosis by phosphorylating and activating enzymes regulating chromatin condensation, nuclear membrane breakdown, mitosis-specific microtubule reorganization, and the actin cytoskeletion allowing for mitotic rounding up of the cell.

How is Cdk1 regulated?

Does M CDK inhibit mitosis?

As a result, the decline in M-Cdk activity that occurs in late mitosis triggers the rapid accumulation of Sic1 protein, and this CKI helps ensure that M-Cdk activity is stably inhibited after mitosis. In most cells, M-Cdk inactivation in late mitosis also results from decreased transcription of M-cyclin genes.