Figure 1

Splitting of 70S ribosomes and their complexes with mRNA and tRNA^Phe by IF3, by IF1 and IF3 or by RRF, EF-G and IF3. The mixtures from syringe 1 of the stopped-flow instrument were rapidly mixed with equal volumes of the mixture from syringe 2 containing (A) 2 M IF3, (B) 2 M IF3 and 5 M IF1 or (C) 2 M IF3, 9 M RRF and 4 M EF-G. Syringe 1 contained 0.3 M vacant 70S ribosomes (); 0.3 M 70S ribosomes pre-incubated with 0.5 M mXR7 mRNA (), with 0.5 M mBar mRNA (), with 0.5 M deacylated tRNA^Phe (), with both mXR7 mRNA and tRNA^Phe () or 0.3 M 70S ribosomes but with mXR7 mRNA added in syringe 2 (). All mixtures were prepared in LS4 buffer containing 4 mM free Mg²⁺. All concentrations in the figure legends are given as final concentrations after the mixing.