The cyclic adenosine monophosphate phosphodiesterases of myoblasts, fibroblasts, and their somatic cell hybrids.

Three forms of cAMP phosphodiesterases are found in mouse L cells (fibroblasts) and rat skeletal myoblasts. The myoblast enzymes can be resolved by chromatography on DEAE-cellulose and the fibroblast enzymes by chromatography on DEAE-Biogel. The myoblast enzymes are "high affinity" cAMP specific forms and have different molecular weights, while all L-cell enzymes have an apparent molecular weight of 450,000. Only one of the L-cell enzymes is able to hydrolyze both cyclic guanosine monophosphate (cGMP) and cAMP. Hydrolysis of the latter is stimulated by micromolar amounts of cGMP. The myoblast x L cell hybrids possess at least five phosphodiesterases, three of which can be identified as being of myoblast or fibroblast origin. One of the fibroblast enzymes appears to be modified in hybrids. The entire phosphodiesterase regulatory system of the myoblasts is active in the hybrids.