INTERACTIONS OF EUKARYOTIC ELONGATION-FACTOR-2 WITH ACTIN - A POSSIBLE LINK BETWEEN PROTEIN SYNTHETIC MACHINERY AND CYTOSKELETON

Eukaryotic elongation factor 2 (EF-2) was shown to bind to F-actin as assayed by co-sedimentation. In the presence of guanosine-5'-O-(3-thio triphosphate) (GTP gamma S) binding was increased fourfold. At saturat ion level a molar ratio of about 0.12 EF-2 per F-actin (subunit) was o bserved. Our results suggest a single type of binding site with an app arent dissociation constant of 0.85 mu M. The stoichiometry was indepe ndent of the filament length, and ADP-ribosylation had no effect on th e binding. Experimental data indicated the involvement of SH-groups of both EF-2 and actin in the binding. The interaction EF-2 with F-actin appeared to be inhibited competitively by EF-1 alpha and non-competit ively by G-actin.