Identification of an ionic strength sensitive nuclear protein kinase activity from the cervical carcinoma HeLa

A cyclic nucleotide independent, serine-threonine protein kinase activity has been purified approximately 700 fold from the nuclei of HeLa cells. This activity has a very strict ionic strength requirement. Maximum activity is obtained in a monovalent cation environment under 50 mM, where Mg++ is preferred over Mn++ as the required divalent cation.