FIG. 2.
Analysis of the peptidyl-tRNA, TnaC-tRNA, accumulated in vitro in translation assays. Translation reactions were carried out in vitro using an E. coli S-30 preparation and various mRNAs containing the genetic changes indicated. The mRNA containing tnaC of P. vulgaris with the change Δstop codon corresponds to a truncated mRNA with a 3′ end at the third nucleotide of the Lys34 codon. Northern blot assays were performed using a 32P-labeled oligonucleotide complementary to E. coli tRNAPro (A and C) or tRNALys (B) sequences. Accumulation of the peptidyl-tRNA was determined from reaction mixtures containing the mRNAs indicated, in the presence or absence of 2 mM l-Trp. The positions of the peptidyl-tRNAs, TnaC-tRNAPro, and TnaC-tRNALys, as well as their corresponding free tRNAs, are indicated with arrows. Pv, P. vulgaris; Ec, E. coli.