Catalytic domain of the Serine/Threonine Kinase, Novel Protein Kinase C epsilon
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. PKC-epsilon has been shown to behave as an oncoprotein. Its overexpression contributes to neoplastic transformation depending on the cell type. It contributes to oncogenesis by inducing disordered cell growth and inhibiting cell death. It also plays a role in tumor invasion and metastasis. PKC-epsilon has also been found to confer cardioprotection against ischemia and reperfusion-mediated damage. Other cellular functions include the regulation of gene expression, cell adhesion, and cell motility. PKCs are classified into three groups (classical, atypical, and novel) depending on their mode of activation and the structural characteristics of their regulatory domain. nPKCs are calcium-independent, but require DAG (1,2-diacylglycerol) and phosphatidylserine (PS) for activity. The nPKC-epsilon subfamily is part of a larger superfamily that includes the catalytic domains of other STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.