Tissue Distribution,Developmental Changes and Some Catalytic Properties of Guanosine 3′,5′-Monophosphate-dependent Protein Kinase of Bombyx mori

The levels of guanosine 3′,5′-monophosphate (cGMP)-dependent protein kinase in the larval and pupal tissues of Bombyx mori were estimated. This activity was highest in the fat body of the female pupa. The enzyme showed a significant variation in activity during development of adult in female. Male silkworm gave less significant results. The cGMP-dependent kinase partially purified from the pupa could be activated by a high concentration of adenosine 3′,5′-monophosphate (cAMP) as reported for cGMP-dependent protein kinases from other sources. The nature of the enzyme thus activated and that of the enzyme activated by a low concentration of cGMP were found to be similar in several aspects. This indicates that the intrinsic activity of protein kinase from the silkworm pupa is independent of the kind of cyclic nucleotide as an activator.