Catalytic domain of the Serine/Threonine Kinase, Classical Protein Kinase C alpha
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. PKC-alpha is expressed in many tissues and is associated with cell proliferation, apoptosis, and cell motility. It plays a role in the signaling of the growth factors PDGF, VEGF, EGF, and FGF. Abnormal levels of PKC-alpha have been detected in many transformed cell lines and several human tumors. In addition, PKC-alpha is required for HER2 dependent breast cancer invasion. PKCs are classified into three groups (classical, atypical, and novel) depending on their mode of activation and the structural characteristics of their regulatory domain. PKCs undergo three phosphorylations in order to take mature forms. In addition, cPKCs depend on calcium, DAG (1,2-diacylglycerol), and in most cases, phosphatidylserine (PS) for activation. The cPKC-alpha subfamily is part of a larger superfamily that includes the catalytic domains of other protein STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.
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