Cyclic AMP-dependent protein kinases of Paramecium. I. Chromatographic and physical properties of the enzymes from cilia.

The cAMP-dependent protein kinases of the cilia of the protozoan Paramecium tetraurelia were resolved and characterized. Two cAMP-dependent activities were present in cilia; the two ciliary kinases resemble types I and II from vertebrate tissues. Part of the ciliary kinase activity (primarily type II) was released by freeze-thawing, but a significant amount remained particulate. Both kinases were found as aggregates of about 220 kDa and of about 70 kDa. A portion of the cAMP-binding activity in ciliary extracts separated from kinase activity, and eluted at 36 kDa during gel filtration. Photoaffinity labeling with 8-azido-cAMP identified cAMP-binding proteins of 45-52 kDa in type II kinase from cilia, and of 43-46 kDa in type I kinase. The type II kinase was apparently autophosphorylated, causing a decrease in mobility during sodium dodecyl sulfate-polyacrylamide gel electrophoresis.