FIG. 2.

Sensitivity of uORF2 missense mutations to eRF1 effects. Full-length β-Gal transcripts with leaders containing uORF2 mutations were translated in cell-free reactions to which 0.2 μM wild-type eRF1 (WT) or AA-eRF1 (AA) was added. The translation ratio represents β-Gal activity measured after addition of exogenous AA-eRF1 compared to that found after addition of wild-type eRF1 for each RNA. Bars represent the mean ratio (plus standard deviation) obtained from at least two separate experiments in which each RNA was assayed in triplicate. The actual β-Gal activities (means plus or minus standard deviation of triplicate reactions) obtained from representative translations of each RNA are shown below the bars. The wild-type 22 codon uORF2 peptide sequence and amino acids that varied among the transcripts tested are shown below.