A pseudosubstrate peptide inhibits protein kinase C‐mediated phosphorylation in permeabilized Rat‐1 cells

Abstract

Activation of protein kinase C (PKC) in Rat-1 fibroblasts leads to rapid phosphorylation of an 80-kDa protein, a major substrate of PKC. Digitonin-permeabilized cells perfectly supported this early response. Introduction of a PKC pseudosubstrate peptide inhibited 80 kDa phosphorylation with an IC50 of 1 microM, while a control peptide had no effect. The results indicate that this semi-intact cell system can be used in combination with the inhibitory pseudosubstrate peptide to study the involvement of PKC in cellular processes.