Protein Kinase C (19-31), (C67H118N26O17), a peptide with the sequence H-ARG-PHE-ALA-ARG-LYS-GLY-SER-LEU-ARG-GLN-LYS-ASN-VAL-OH, MW= 1559.82. this peptide derived from the pseudo-substrate regulatory domain of PKCa (residues 19-31) with a serine at position 25 replacing the wild-type alanine, it was used as protein kinase C substrate peptide for testing the protein kinase C activity. Protein kinase C also known as PKC, is a family of protein kinase enzymes that are involved in controlling the function of other proteins through the phosphorylation of hydroxyl groups of serine and threonine amino acid residues on these proteins. PKCa has been reported to play roles in many different cellular processes, such as cell adhesion, cell transformation, cell cycle checkpoint, and cell volume control. Knockout studies in mice suggest that this kinase may be a fundamental regulator of cardiac contractility and Ca2+ handling in myocytes.