[Protein kinase activity of proteins extracted by triton X-100 from isolated rat liver cell nuclei and Zajdela hepatoma].

Proteins extracted with Triton X-100 from rat liver tissue and Zajdela hepatoma nuclei exhibited similar electrophoretic properties of both proteins and phosphoproteins if they were separated by means of electrofocusing. Four protein-kinase activity peaks were detected in each of these preparations. Three protein-kinases from rat liver tissue and Zajdela hepatoma were similar in their electrofocusing point and substrate specificity. However, the fourth protein-kinase, which had pI 6.1-6.3 and was activated by rabbit muscle thermostable proteins, was detected only in the preparation of rat liver tissue, while the enzyme with isoelectric point at pH 4.0 was found only in Zajdela hepatoma preparation. All the protein-kinases studied phosphorylated nuclear matrix proteins at higher rate as compared with histones.