A cAMP-dependent protein kinase is present in differentiating Dictyostelium discoideum cells.
We demonstrate the occurrence of a cAMP-dependent protein kinase in Dictyostelium discoideum cells at the terminal stage of differentiation. A cAMP-binding component was purified to homogeneity by affinity chromatography. This subunit inhibits the activity of purified catalytic subunit from beef heart protein kinase; the inhibition is reversed upon addition of cAMP. The protein is highly specific for cAMP and has a dissociation constant of 4 nM. The isolated regulatory subunit is a monomer of 39 K, with a sedimentation coefficient of 3.5S and a frictional coefficient of 1.24. The differences between this regulatory subunit and regulatory subunits of protein kinases from other sources are discussed.
Gunzburg
J
J
Unité de Biochimie Cellulaire, Départment de Biochimie et Génétique Moléculaire, Institut Pasteur, 28, rue du Docteur Roux, 75724 Paris Cedex 15, France.
Veron
M
M