Complexes of EcoRRF, EcoDI/TteDII, TteDI/EcoDII or TteRRF (4 μM) with 70 S ribosomes (0.25 μM) were formed in 40 μl of assay buffer solution as described in the Material and methods section. (A) Various amounts of EcoEF-G (0.05, 0.125, 0.25, 0.5, 0.75 and 1.0 μM) and GTP (0.5 mM) were then added and incubated at room temperature for 15 min. The mixture was subjected to Microcon-100 ultrafiltration to separate the ribosomes from the released RRFs. The remaining ribosome-bound RRFs were determined by quantitative Western blotting. The RRFs bound to ribosomes in the absence of EF-Gs was taken as 100%. (B) Various amounts of TteEF-G (0.05, 0.125, 0.25, 0.5, 0.75 and 1.0 μM) and GTP (0.5 mM) were applied to the assay system. Others are the same as in (A).