Cyclin-dependent kinase

Definition

Cyclin-dependent kinases (CDKs) are a family of protein kinases that play a crucial role in regulating the cell cycle by phosphorylating target proteins. They are activated by binding to cyclins, which are regulatory proteins whose levels fluctuate throughout the cell cycle, thus ensuring that the cell progresses through different phases in a controlled manner.

5 Must Know Facts For Your Next Test

1. CDKs are essential for the proper timing and coordination of the cell cycle, with specific CDKs being active during particular phases.
2. The activation of CDKs is regulated by cyclins; without cyclins, CDKs remain inactive and cannot phosphorylate target proteins.
3. Each cyclin-CDK complex is specific to a particular stage of the cell cycle, ensuring that events like DNA replication and mitosis occur in the right order.
4. Abnormal regulation of CDKs can lead to uncontrolled cell division and contribute to cancer development.
5. In addition to cell cycle regulation, CDKs also play roles in other cellular processes such as transcription and DNA repair.

Review Questions

• How do cyclins regulate the activity of cyclin-dependent kinases during the cell cycle?
  • Cyclins regulate cyclin-dependent kinases by binding to them to form active cyclin-CDK complexes. The levels of cyclins fluctuate throughout the cell cycle, which determines when specific CDKs are activated. This mechanism ensures that CDKs phosphorylate their target proteins at the right time, allowing for orderly progression through different phases such as DNA replication and mitosis.
• Discuss the consequences of dysregulation of cyclin-dependent kinases in cellular processes.
  • Dysregulation of cyclin-dependent kinases can lead to serious consequences such as uncontrolled cell proliferation. When CDKs are overactive or not properly regulated by cyclins, it can result in cells bypassing critical checkpoints in the cell cycle. This lack of control is a significant factor in cancer development, where cells continue to divide without adhering to normal regulatory mechanisms, leading to tumor formation.
• Evaluate the potential therapeutic implications of targeting cyclin-dependent kinases in cancer treatment.
  • Targeting cyclin-dependent kinases presents a promising approach in cancer treatment by potentially restoring normal cell cycle regulation. Inhibiting specific CDKs could slow down or stop the proliferation of cancer cells, particularly those that rely heavily on these pathways for growth. Developing selective CDK inhibitors can lead to therapies that may minimize side effects compared to traditional chemotherapy by selectively targeting cancerous cells while sparing normal cells.

Related terms

Cyclin: Cyclins are proteins whose concentrations vary in the cell cycle, and they activate CDKs by forming cyclin-CDK complexes that trigger progression through specific phases of the cell cycle.

Cell Cycle: The cell cycle is a series of phases (G1, S, G2, and M) that a cell goes through to divide and replicate its DNA, with checkpoints that ensure proper progression and prevent errors.

Phosphorylation:

Phosphorylation is a biochemical process where a phosphate group is added to a molecule, such as a protein, often modifying its function and activity; in this context, it is key for activating CDKs.