CDK

Definition

Cyclin-dependent kinases (CDKs) are a family of protein kinases that play crucial roles in regulating the cell cycle by modifying target proteins through phosphorylation. They are activated by binding to cyclins, which are regulatory proteins whose levels fluctuate throughout the cell cycle. This interaction ensures that the cell cycle progresses in a timely manner and that cellular activities are coordinated, linking cell division with growth and developmental signals.

5 Must Know Facts For Your Next Test

1. CDKs are essential for the progression through key phases of the cell cycle, such as G1 to S phase and G2 to M phase.
2. The activity of CDKs is tightly regulated by cyclins and CDK inhibitors to ensure proper cell cycle control and prevent uncontrolled cell proliferation.
3. Mutations or dysregulation of CDKs can lead to cancer, as they may result in unchecked cell division and growth.
4. Different CDKs are active at different points in the cell cycle; for example, CDK1 is primarily involved in the transition from G2 to M phase.
5. CDKs also play roles outside of the cell cycle, including regulation of transcription, apoptosis, and differentiation.

Review Questions

• How do CDKs interact with cyclins to regulate the cell cycle?
  • CDKs require binding with cyclins to become active. When a cyclin binds to a CDK, it induces a structural change that activates the kinase activity. This activated CDK then phosphorylates target proteins, driving the cell through specific checkpoints in the cell cycle. This interaction is crucial for ensuring that cells only progress when conditions are appropriate.
• Discuss the implications of CDK dysregulation in relation to cancer development.
  • Dysregulation of CDKs can lead to cancer because it disrupts normal cell cycle control. If CDKs are overactive or if their inhibitors are dysfunctional, cells may proliferate uncontrollably. This uncontrolled growth can result in tumor formation as cells bypass critical checkpoints that normally prevent damaged or unprepared cells from dividing. Understanding CDK regulation is key for developing targeted cancer therapies.
• Evaluate how CDKs integrate various cellular signals to control the progression of the cell cycle.
  • CDKs integrate multiple signaling pathways, responding to growth factors, nutrient availability, and DNA damage signals. By doing so, they ensure that the cell only progresses through the cycle when conditions are favorable. For instance, if DNA damage is detected, specific proteins can inhibit CDK activity, preventing entry into mitosis until repairs are made. This level of integration highlights how CDKs act as central regulators that align cellular division with overall cellular health and environmental conditions.

Related terms

Cyclins:

Proteins that regulate the activity of CDKs by binding to them, causing a conformational change that activates the kinase activity.

Cell Cycle: The series of events that a cell goes through as it grows and divides, consisting of distinct phases: G1, S, G2, and M.

Phosphorylation:

The process of adding a phosphate group to a molecule, often used to activate or deactivate proteins in various cellular processes.