Effect of S1 on translation and trans-translation in vitro. (A) Effect of S1 on poly (U)-dependent poly (Phe) synthesis was examined by performing the reaction with 0 (closed circles), 0.3 (open circles), 0.6 (closed triangles), and 1.2 (open triangles) μM S1. The reaction mixture including S1 was prepared on ice without GTP, and the reaction was started by the addition of GTP. (B) The effect of S1 on trans-transfer was examined in the system shown in Fig. 1A. [3H]Ala-tmRNA and SmpB with 0 (closed circles), 1.5 (open circles), 3.0 (closed triangles), or 6.0 (open triangles) μM S1 were added to the stalled ribosome and incubated (final concentration of S1 in the reaction mixture: 0, 0.3, 0.6, or 1.2 μM). The values of experiments without SmpB were subtracted as backgrounds. (C) The effect of S1 on the resume codon decoding was examined. Unlabeled Ala-tmRNA, [3H]Ala-tRNAAla, and 0 (closed circles), 1.5 (open circles), 3.0 (closed triangles), or 6.0 (open triangles) μM S1 were added to the stalled ribosome. The average results of at least three independent experiments are shown with standard errors.
