FIGURE 2.

Stop codon and the distal nucleotide at position +4 have small effects on the rate of peptide release. A, the rate constant for peptide release at saturating release factor concentrations depends slightly on the stop codon and the nucleotide at position +4. The white bars indicate the rate of peptide release mediated by eRF1:eRF3:GTP, whereas the black bars indicate the rate of peptide release mediated by eRF1 alone. B, the observed rates of multiple turnover peptide release by eRF1 varies <2-fold across a subset of stop codons and +4 nucleotides. Reactions were carried out as in Fig. 1B. Observed rates are plotted; error bars represent the S.E. C, the observed rates of multiple turnover peptide release by eRF1 and eRF3 depend slightly on stop codon and the nucleotide at position +4. Reactions were carried out as described in Fig. 1B. Observed rates are plotted; error bars represent the range.