Inhibition of Stimulated Cell Responses by Phorbol Esters and Other Activators of Protein Kinase C: Sites of Action

Abstract

The addition of the protein kinase C activator phorbol esters to cell suspension a few minutes prior to stimulation inhibits the agonists-induced biochemical changes and cell responses. This inhibition is prevented by protein kinase C inhibitors. Activation of protein kinase C down regulates the stimulated responses by affecting one or more of the steps in the exitation—response coupling. This includes the receptors, the quanine-nucleotide-binding protein, the activity or distribution of phospholipase C, and other steps.

Key Words:

• Protein kinase C
• G-protein
• down regulation