FIGURE 4.

Translational repression exerted by the EPO uORF is peptide sequence–independent. (A) Schematic representation of the expression constructs. The pGL2-WT plasmid contains the human normal EPO 5′-leader transcript sequence, and the pGL2-frameshift vector carries a EPO uORF sequence modified by frameshift mutations, which consist in the insertion of 1 nt in the second codon (+1 nt) and the deletion of 1 nt in 13th codon (−1 nt). The resulting uORF-encoded peptide sequence is shown below. (B) HEK293, HepG2, and HeLa cells were transiently cotransfected with each one of the constructs described in A and with a plasmid encoding RLuc (pRL-TK) and analyzed as described in the legend to Figure 2B.