Stimulation of enzymatic activity in filament preparations of casein kinase II by polylysine, melittin, and spermine.

Casein kinase II (CKII) has been purified from bovine heart tissue. Under conditions of low salt (0.05 M NaCl, 10 mM MgCl2), CKII forms structured aggregates that appear as filaments similar to results obtained with Drosophila CKII [C.V.C. Glover (1986) J. Biol. Chem. 261:14349]. The aggregates have been analyzed by sucrose density gradients and electron microscopy. Filament preparations of the enzyme have reduced but measurable kinase activity. The addition of salt restores activity. Various modulators of CKII activity have been examined with the enzyme in the low salt, polymerized form. The polyamines spermine or spermidine stimulated CKII activity as much as six fold; putrescine had no effect. Polylysine of varying lengths activated CKII 4-6 fold. Melittin, the basic polypeptide from bee venom, was also an effective activator. Activation of filament preparations was also observed if the CKII specific peptide (RRREEETEEE) was used as the substrate in place of casein. These results with filament preparations provide an alternative in vitro system for the study of possible regulatory aspects of CKII.