Protein kinases in Tetrahymena cilia : II. Partial purification and characterization of adenosine 3′,5′-monophosphate-dependent and guanosine 3′,5′-monophosphate-dependent protein kinases

Abstract

Adenosine 3′,5′-monophosphate (cyclic AMP)- and guanosine 3′,5′-monophosphate (cyclic GMP)-dependent protein kinase (EC 2.7.1.37) activities were detected in the Triton extract of Tetrahymena cilia. When the Triton extract was chromatographed on a DEAE-cellulose column, one peak of cyclic AMP-dependent protein kinase activity and three peaks of cyclic GMP-dependent protein kinase activity were detected, one of which was further purified with CM-Sephadex column chromatography. Two of the cyclic GMP-dependent protein kinases had quite similar properties, prefering histone and casein for substrate, and were specifically activated by a low concentration of cyclic GMP. The other one, cyclic GMP-dependent protein kinase, which preferentially phosphorylated histone and protamine, was less susceptible to cyclic GMP. The activity of cyclic AMP-dependent protein kinase was highly stimulated by a low concentration of cyclic AMP and showed preference for protamine or histone as substrate protein. The apparent molecular weights of all the cyclic GMP-dependent protein kinases were about 1·10 5, that of the cyclic AMP-dependent kinase being about 6·10 4.