Evidence for differences in protein kinase modulator and and phosphodiesterase activator.

Both protein kinase modulator and phosphodiesterase activator activities were present in the supernatant fluid of a homogenate of bovine brain. These were separated on a DEAE-cellulose column chromatography. Separation was also achieved by an isoelectrofocusing fractionation of the supernatant fluid, isoelectric points of proteins kinase modulator and phospodiesterase activator being 4.25 and 4.44, respectively. Phospodiesterase activator was purified from bovine brain to an apparent homogenity by a procedure which did not involve a drastic treatment such as boiling. The purification of phosphodiesterase activator resulted in removing the protein kinase modulator activity and the ratio of the activity of protein kinase modulator to that of phosphodiesterase activator in the sample decreased as the purification proceeded.