Multiple protein kinase activities in the dimorphic fungus Mucor rouxii. Comparison with a cyclic adenosine 3',5'-monophosphate binding protein.

Protein kinase and cyclic adenosine 3′,5′-monophosphate (cAMP) binding activities have been detected in cell extracts of the dimorphic fungus Mucor rouxii. The subcellular distribution of both activities indicates that most of the binding protein is in the high-speed supernatant (S₁₀₀), while about 70% of the total protein kinase activity remains in particulate fractions. S₁₀₀ preparations have been analyzed by diethylaminoethyl cellulose column chromatography. Binding activity can be resolved in two peaks (A and B) and protein kinase in three peaks (I, II, and III). Peaks I and II are casein dependent and insensitive to cAMP. Peak III utilizes histone as substrate and is activated (two- to fourfold) by cAMP. Theophylline strongly inhibits cAMP binding activity and mimics the effect of cAMP on cAMP-dependent protein kinase. The possible relationship between cAMP binding activity and cAMP-dependent protein kinase is suggested.