Casein and histone kinases of a rat ascites hepatoma as compared with those of rat liver

Abstract

Seryl/threonyl-protein kinases in cytosolic and particulate fractions from rat liver and AH-13, a rat ascites hepatoma, have been studied by chromatographing these fractions on DEAE-cellulose and assaying the eluates with casein, phosvitin, histone and protamine as substrates. Liver cytosolic fraction contains a group of well-characterized seryl/threonyl-protein kinases, namely, casein kinases I and II and histone kinases I and II. Liver particulate fraction, on the other hand, is almost totally devoid of casein kinase I and histone kinase I but contains an additional peak of casein kinase tentatively designated casein kinase III. In AH-13, cytosolic casein kinase I is markedly increased and particulate-associated casein kinases II and III are moderately increased as compared with liver. Moreover, it was found that in AH-13, the histone kinase I level is high in the particulate fraction but markedly decreased in the cytosolic fraction. It is suggested that particulate-associated histone kinase I may be of cytosolic origin.