Further studies on the ionic strength-dependent proteolytic activation of protein kinase C in rat liver plasma membrane by endogenous trypsin-like protease.
cAMP and Ca2(+)-independent histone kinase was generated from rat liver plasma membrane in an ionic strength-dependent manner by the action of an endogenous trypsin-like protease (Hashimoto, E. et al. (1986) FEBS Lett. 200, 63-66). In addition to the effect of ionic strength, this proteolytic activation of protein kinase proceeded faster at alkaline pH. In an attempt to identify the activated kinase as the protease-activated form of protein kinase C (protein kinase M), the active enzyme released from plasma membrane was highly purified and characterized. Various properties including Mg2+ requirement in histone phosphorylation, substrate specificity, effects of protein kinase activators, and inhibitors and comparison of catalytic properties by peptide map analysis were compatible with those of protein kinase M reported earlier. Immunoblot analyses also supported the idea that the protein kinase subjected to proteolytic activation was protein kinase C. The subtype of protein kinase C detected in this study was identified as type III enzyme encoding alpha-type sequence from the elution profile from hydroxyapatite column. These results suggest that type III protein kinase C bound to rat liver plasma membrane has an ability to be activated by endogenous trypsin-like protease dependently on the alteration of ionic strength and pH around the plasma membrane.
Hashimoto
E
E
Department of Biochemistry, Fukui Medical School.
Yamamura
H
H
D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D004789:Enzyme Activation; D006863:Hydrogen-Ion Concentration; D015151:Immunoblotting; D007527:Isoenzymes; D008099:Liver / Q000201:enzymology*; D009994:Osmolar Concentration; D011493:Protein Kinase C / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012697:Serine Endopeptidases / Q000502:physiology
D007527:Isoenzymes; D011493:Protein Kinase C; D012697:Serine Endopeptidases