PROTEIN KINASES .4. PROTEIN-KINASE CK2 - AN ENZYME WITH MULTIPLE SUBSTRATES AND A PUZZLING REGULATION

Protein kinase CK2 (also known as casein kinase II) is a ubiquitous eu karyotic ser/thr protein kinase present in the nucleus and cytoplasm. CK2 is known to phosphorylate more than 100 substrates, many of which are involved in the control of cell division and in signal transductio n. The review centers on the structure and function of CK2 alpha and b eta subunits and on the regulation of its activity, a topic that remai ns to be elucidated. An analogy is drawn between CK2 and the cyclin-de pendent kinases (cdks); both types of protein kinases share many subst rates and are activated by regulatory subunits.