| Modification Notes |
Members of the protein kinase C (PKC) family play a key regulatory role in a variety of cellular functions, including cell growth and differentiation, gene expression, hormone secretion and membrane function. PKCs were originally identified as serine/threonine protein kinases whose activity was dependent on calcium and phospholipids. Diacylglycerols (DAG) and tumor promoting phorbol esters bind to and activate PKC. PKCs can be subdivided into at least two major classes, including conventional (c) PKC isoforms (å, ∫I, ∫II and ©) and novel (n) PKC isoforms (∂, é , Ω, h and †). PKC isoforms can be activated through tyrosine phosphorylation and catalytically activated upon treatment with H2O2. The Tyr 155, 525, 523 and 565 residues in the catalytic domain are crucial for activation of these enzymes. The residue Ser 643 appears to be an autophosphorylation site. PKC theta can undergo autophosphorylation on serine 676 (Ser 676) in the turn loop and serine 695 (Ser 695) in the hydrophobic loop. Phosphorylation of serine 676 may negatively regulate activation of NF-kappa B. Ser-695 is crucial to activate the phosphorylation threonine 692 (Thr 692) and threonine 703 (Thr 703) residues, both of which are necessary for mobility shift. |
