Protein kinase C

Definition

Protein kinase C (PKC) is a family of enzymes that play crucial roles in various cellular signaling pathways by phosphorylating specific serine and threonine residues on target proteins. This phosphorylation process can lead to diverse effects such as cell growth, differentiation, and apoptosis, making PKC essential for responding to signals from hormones and other stimuli.

5 Must Know Facts For Your Next Test

1. PKC is activated by diacylglycerol (DAG) and calcium ions, allowing it to phosphorylate target proteins and modulate their activity.
2. Different isoforms of PKC exist, each with distinct functions and tissue distributions, contributing to the specificity of signaling pathways.
3. PKC plays a vital role in mediating the effects of various hormones, including insulin and growth factors, linking extracellular signals to intracellular responses.
4. Aberrant PKC activity has been implicated in various diseases, including cancer and diabetes, highlighting its importance in maintaining cellular homeostasis.
5. PKC is involved in several physiological processes, including immune response, cardiovascular function, and neuronal signaling.

Review Questions

• How does protein kinase C contribute to the regulation of cellular activities in response to external signals?
  • Protein kinase C contributes to cellular regulation by phosphorylating specific proteins in response to external signals like hormones. When activated by diacylglycerol and calcium ions, PKC modifies target proteins' activities, influencing critical processes such as cell growth, differentiation, and apoptosis. This phosphorylation is essential for translating the signals from the extracellular environment into appropriate cellular responses.
• Evaluate the role of different isoforms of protein kinase C in cellular signaling pathways.
  • Different isoforms of protein kinase C have unique roles and tissue distributions, allowing them to participate in diverse cellular signaling pathways. For example, certain isoforms may be more involved in growth factor signaling while others may play roles in apoptosis or immune responses. This specificity enables cells to fine-tune their responses to various stimuli based on the particular PKC isoform that is activated in that context.
• Discuss the implications of dysregulated protein kinase C activity in human diseases such as cancer and diabetes.
  • Dysregulated protein kinase C activity can lead to significant health issues like cancer and diabetes. In cancer, abnormal PKC signaling may promote uncontrolled cell proliferation and survival, contributing to tumor growth. In diabetes, altered PKC activity can affect insulin signaling pathways, leading to impaired glucose metabolism. Understanding these connections highlights the importance of PKC as a therapeutic target for managing these diseases and emphasizes its role in maintaining cellular health.

Related terms

Phosphorylation: The process of adding a phosphate group to a molecule, typically a protein, which can alter its function and activity.

Signal Transduction: The process by which a cell converts an external signal into a functional response, often involving a cascade of biochemical events.

Diacylglycerol: A lipid molecule that acts as a second messenger in cellular signaling, particularly in activating protein kinase C in response to various stimuli.