Fig. 3.

Termination activities of bacterial RFs at modified stop codons using IVT assays. (A–C) The efficiency of termination at the modified stop codons was deduced from the yield of a 1.6-kDa-sized ErmCL peptide determined by Tricine-SDS/PAGE. Read-through of the modified stop codon resulted in termination at a second unmodified UAA stop codon reflected by a 2.2-kDa translation product (A and C). (D–F) Translation products shown in A–C were quantified (error bars show SDs from the mean of three independent experiments). (G–I) The release activities of RF mutants—i.e., RF1* and RF2*—were tested in the peptide release assay (G) and in the IVT-based assay (H and I). In G, significant differences between RF1, RF2 and RF1*, RF2*, respectively, were determined by using the two-tailed unpaired Student’s t test. ***P < 0.001; **P < 0.01.