A monoclonal antibody recognising the site of limited proteolysis of protein kinase C. Inhibition of down-regulation in vivo.

A monoclonal antibody to protein kinase C is described that recognises the site of limited proteolysis on the native enzyme. Binding of the antibody to the purified kinase in vitro blocks partial proteolysis by trypsin, and introduction of the Fab fragment into a rodent glioma cell line inhibits phorbol-ester-induced down-regulation of the kinase. These observations are discussed in the context of the domain structure of protein kinase C and the agonist-induced proteolysis of the kinase in vivo.