Cytosolic cAMP-dependent protein kinase of Polysphondylium violaceum: developmental regulation and properties.

The cellular slime mould Polysphondylium violaceum contains a cAMP-dependent protein kinase resembling the mammalian type I enzyme. The appearance of this enzyme is developmentally regulated. The level of kinase activity is very low in vegetative cell and increases more than tenfold during differentiation. The catalytic subunit of this cAMP-dependent protein kinase has a native molecular weight of 60-80 kDa, an isoelectric point of 5.7 and an apparent Km for ATP and Kemptide of 50 and 13.4 microM respectively. It is characterised by its sensitivity to a synthetic inhibitor specific for cAMP-dependent protein kinase. The regulatory subunit has a molecular weight of 50 kDa.