FIGURE 5.

Fits to the Hill equation for wild-type recovery and UAA incorporation at α149. Suppression of tRNA-W (9 ng per oocyte) at α149(UAG or UGA) places the natural amino acid and results in wild-type EC₅₀ (∼50 μM ACh) for all tRNAs tested except TQOpS-W (white diamond), which gave the same EC₅₀ in two experiments (see Table 2). Incorporation of WF1 at α149 results in a fourfold increase in EC₅₀ (200 μM ACh) (Zhong et al. 1998). All tRNA-WF1 suppressing at α149(UAG or UGA) give similar EC₅₀s and show that all tRNAs are able to incorporate an UAA. All experiments were done in Nasco oocytes and give the same EC₅₀s as W or WF1 incorporation in Xenopus Express oocytes (Rodriguez et al. 2006). EC₅₀s, n _H, and n are listed in Table 2.