Domain structure and phosphorylation of protein kinase C.
The phospholipid- and calcium-dependent protein kinase C has been shown to autophosphorylate on both the catalytic and the regulatory domains. The autophosphorylation displays zero-order kinetics, indicating that it is an intramolecular event. Autophosphorylation increases the activity of protein kinase C by decreasing the Km for the substrate H1 histone. The catalytic fragment obtained by limited proteolysis can no longer autophosphorylate and has a reduced affinity for H1 histone, exhibiting a Km 5-fold higher than that of the intact enzyme. Monoclonal antibodies produced against the enzyme can distinguish between the catalytic fragment and the intact enzyme by inhibiting their activities in a specific manner. Evidence suggesting that dimerization of protein kinase C occurs upon activation is presented.
D000818:Animals; D000911:Antibodies, Monoclonal; D002852:Chromatography, Ion Exchange; D004789:Enzyme Activation; D006657:Histones / Q000378:metabolism; D007700:Kinetics; D008297:Male; D010766:Phosphorylation; D011108:Polymers; D011487:Protein Conformation; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014357:Trypsin / Q000378:metabolism
D000911:Antibodies, Monoclonal; D006657:Histones; D011108:Polymers; D011493:Protein Kinase C; D014357:Trypsin