Prereplicative modulation of nuclear protein kinases in the regenerating rat liver

Partial hepatectomy in the rat is followed by a significant increase of nuclear protein content and by an increase of total nuclear protein kinase activity. Total nuclear protein kinase activity is maximal 16 hours after partial hepatectomy. Analysis of nuclear 0.35 M NaCl extracts by DEAE-Sephacel chromatography reveals the presence of four species of protein kinase, two of which are of the cAMP-dependent type. By 16 hours after partial hepatectomy the two nuclear cAMP-dependent protein kinase activities have increased several fold over the kinase activities found in liver nuclei of sham-operated controls. These data indicate a prereplicative modulation of nuclear protein kinase activities following the second wave of cAMP accumulation in the regenerating rat liver.