Site-directed mutagenesis of glutamine residue of calmodulin. Activation of guanylate cyclase of Tetrahymena plasma membrane

A calcium-dependent protein kinase is present in tetrahymena

A Ca(2+)-dependent protein kinase of Tetrahymena thermophila has been partially purified and characterized. The molecular mass of the enzyme is less than that of similar enzymes (for example protein kinase C), being about 55 kDa. After purification and in the presence of Ca2+ the enzyme activity increased. The promoter of protein kinase C (PKC) activity, phorbol myristate acetate (PMA), increased the activity while the protein kinase inhibitor H-7 decreased the activity of the enzyme. The experiments demonstrate the presence, activity and similarity to vertebrate enzymes of a protein kinase at a low level of phylogeny.

Calmodulin cDNAs from two species of Tetrahymena

We describe the isolation and characterization of cDNAs encoding calmodulins of Tetrahymena thermophila and Tetrahymena pyriformis. It reveals that the deduced amino acid sequences of both calmodulins are precisely the same.