Figure 3.

Activities of eIF1, IF3, IF3-CTD and YciH in promoting ribosomal dissociation and formation of 43S complexes. Dissociation of (A) 70S and (B) 80S ribosomes in the presence of factors as indicated. The optical density of ribosomal profiles was measured after centrifugation through 10–30% sucrose density gradients. The positions of ribosomes and ribosomal subunits are indicated. (C, D) 43S complex formation in reaction mixtures containing [³⁵S]Met-tRNA_i^Met, 40S subunits and factors as indicated was assayed by centrifugation through 10–30% sucrose density gradients. Aliquots of gradient fractions were analyzed by scintillation counting. The position of 43S complexes is indicated. Fractions from upper parts of gradients were omitted for clarity.