FIGURE 3.

Nucleotides within domain 2 are important for efficient internal initiation of translation on the URE2 minimal IRES element. (A) Base-pair X in domain 2 (nucleotides A235 and U272) was mutated, and IRES activity was measured. (B) Bulge Y in domain 2 (nucleotides A238 and C269) was mutated, and IRES activity was measured. In A and B, activity measurements were conducted using the p281-4 reporter plasmid in both wild-type (gray bars) and ΔeIF2A yeast (2A-KO; black bars) cells, and represented as in Figure 2 (Altmann et al. 1993). Mutations in the minimal URE2 IRES element are indicated.