Figure 4

Truncations and ameloride treatment identify regions in the FMR1 5' leader important for IRES activity. (A) Dicistronic luciferase mRNA containing the β-globin, FMR1, or serial 5' truncations of the FMR1 5' leader inserted into the intercistronic region were transfected into C6 cells. C6 cells were exposed to ameloride for 24 hr or untreated. Luciferase activity is shown as the P:R ratio and is normalized to the activity from the β-globin mRNA. (B) Dicistronic luciferase mRNA containing the full length FMR1 5' leader, FMR1 5' leader with an internal deletion of the CGG repeats (FMRΔCGG), or the β-globin 5' leader inserted into the intercistronic region was transfected into C6 cells. Luciferase activity is shown as the P:R ratio and is normalized to the activity from the β-globin mRNA. Each experiment was performed in triplicate, n = 3.