Reconstitution of a Cyclic Amp-dependent Protein Kinase From

The study of protein kinase in Dictyostelium discoideum has a tortuous history. The cyclic AMP-dependent protein kinase was first reported by Sampson [1]. Upon DEAE chromatography of cells starved for 2 h he found two cAMP-dependent and two cAMP-independent activities. Shortly thereafter reports by Veron and Patte [2] and Rahmsdorf and Gerisch [3] described protein kinase activity but no cAMP activation was reported. Leichtling et al. [4] demonstrated that bovine protein kinase catalytic subunit could be inhibited by the purified Dictyostelium cAMP binding protein. Recently Leichtling et al. [5] reported that DEAE chromatography can be used to demonstrate cAMP-dependent protein kinase activity when the substrate used is the synthetic heptapeptide, kemptide. Cyclic AMP is a central molecule in the developmental cycle of Dictyostelium. During aggregation it is the molecule which mediates the chemotactic response, and there is evidence that cAMP is also involved in the processes of cell differentiation [6-9]. Our efforts have been directed toward