Regulation of Protein Kinase C Activity

Proteolytic cleavage of PKC isozymes in the variable region (V3) that separates the regulatory and catalytic 

Association of the inactive kinase with membrane PS provides access of the kinase to activator DAG, resulting in a conformational change that exposes the active site in the kinase (Bell and Burns, 

In addition to allosteric regulation of PKC activity by membrane phospholipids, it has become apparent that phosphorylation of the kinase itself is an important regulatory mechanism. Using site-directed mutagenesis approaches, phosphorylation of PKCa on Thr 97 (Cazaubon etal., 1994) or PKC(3II on Thr (Orr and Newton, 1994) has been shown to be essential for catalytic activity. The catalytic subunit of protein phosphatase 1 specifically dephosphorylates this site, resulting in an inactive kinase that has no intrinsic capacity to rephosphorylate and activate when phosphatase is removed (Dutil et al., 1994). Based on this, and an analysis of the sequence around this site, it has been hypothesized that fransphosphorylation of Thr is catalyzed by an unidentified proline-directed protein 

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