it is suggested ( i ) that phosphorylation of the 'dense-vesicle ' phosphodiesterase by a-kinase leads to its activation , and that such a process accounts for the ability of glucagon and other hormones , which increase intracellular cyclic amp concentrations , to activate this enzyme , and ( ii ) that an as yet unidentified kinase can phosphorylate this enzyme without causing any significant change in enzyme activity but which prevents activation and phosphorylation of the phosphodiesterase by a-kinase .
C0031715
phosphorylation
C0031727
kinase