Insulin Signaling

Insulin is a hormone that helps cells take in glucose from the blood. It does this by activating a series of proteins called protein kinases. These proteins then trigger a cascade of events that ultimately lead to the transfer of glucose transporters to the plasma membrane, an increase in protein synthesis, and the stimulation of glycogen synthases.

Summary

• Insulin activates two main protein kinases: PKB and MAP kinase.
• These kinases trigger a cascade of events that lead to four main effects:
• Transfer of glucose transporters to the plasma membrane
• Increase in protein synthesis
• Stimulation of glycogen synthases
• Activation of phosphatase 1
• Insulin signaling leads to the transfer of glucose transporters to the plasma membrane by activating a protein called Akt.

Questions

• What are the two main protein kinases that are activated by insulin?
• What are the four main effects of insulin signaling?
• How does insulin signaling lead to the transfer of glucose transporters to the plasma membrane?

Answers

• The two main protein kinases that are activated by insulin are protein kinase B (PKB) and mitogen-activated protein kinase (MAP kinase).
• The four main effects of insulin signaling are:
  * Transfer of glucose transporters to the plasma membrane
  * Increase in protein synthesis
  * Stimulation of glycogen synthases
  * Activation of phosphatase 1
• Insulin signaling leads to the transfer of glucose transporters to the plasma membrane by activating a series of proteins that ultimately phosphorylate a protein called Akt. Akt then phosphorylates a protein called GLUT4, which causes it to be transported to the plasma membrane.