Protein kinases from liver mitochondria of tumour-bearing rats

The mitochondria of liver of Yoshida ascites tumour-bearing rats contained two forms of protein kinase distinguishable on the basis of their kinetic properties, substrate specificity and responses to cyclic adenosine 3',5'-monophosphate (cAMP). One of these (kinase I) was activated 2-3 fold by cAMP while the other form (kinase II) was insensitive to the action of cAMP. Kinase I which was selective towards histone F1 as substrate was obtained as a homogeneous preparation and was observed to have a molecular weight of 170 000 by Sephadex G-150 gel filtration. Protein kinase II appeared to be a smaller protein with molecular weight of 54 000 and was specific towards acidic proteins namely casein and phosvitin. Protein kinases isolated from liver mitochondria of normal rats showed variations in respect to elution profile of DEAE-cellulose and electrophoretic mobility. The preparation corresponding to kinase I did not show stimulatory responses to cAMP.