Guanosinetriphosphatase activity dependent on elongation factor Tu and ribosomal protein L7/L12

Incubation of electrophoretically pure samples of the Escherichia coli 50S ribosomal protein L7/L12 together with elongation factor Tu leads to the hydrolysis of GTP. Addition of elongation factor Ts stimulates this reaction. Elongation factor G cannot replace elongation factor Tu for the ribosome-free GTPase reaction dependent on L7/L12. The data suggest that elongation factor Tu and the protein L7/L12 interact directly at the ribosomal A site.