This peptide corresponds to the residues 19-35 of the pseudosubstrate domain of protein kinase C isoforms alpha and beta. The peptide is a potent inhibitor of both the phosphorylation of protein kinase C substrates (Ki = 147 nM) and the autophosphorylation of protein kinase C whereas it has a low inhibitory activity on protein kinase A (IC50 = 423 mM).Arg-Phe-Ala-Arg-Lys-Gly-Ala-Leu-Arg-Gln-Lys-Asn-Val-His-Glu-Val-Lys or RFARKGALRQKNVHEVK