Staurosporine and gossypol are inhibitors of the function of peptide elongation factor 1 alpha from rabbit reticulocytes.

As it has been found, the incubation of [gamma-32P]ATP with elongation factor--1 alpha purified from rabbit reticulocytes resulted in the phosphorylation of several substrate proteins /Tuhácková, Z. (1992) In: Rec. Adv. Cell. Mol. Biol. 4, 79-86, Peeters Press, Leuven/ (1). In the present paper chromatofocusing of the purified eEF-1 alpha demonstrates that the ATP-dependent protein kinase activity is associated with a single protein catalyzing the GTP-dependent binding of aminoacyl-tRNA to ribosomes. Both of these activities are inhibited by staurosporine and gossypol. The inhibition by GDP but not by GTP indicates a possible involvement of conformation changes also in the modulation of the protein kinase activity displayed by eEF-1 alpha.