FIGURE 5.
Effect of sequence and structure divergence in the C8 region of IREs as a basis for differential recognition by IRP1. (A) Single and multiple base substitutions or a nucleotide deletion were made in the L-ferritin IRE, and their affect on affinity was determined. Base-pair substitutions were made at 10/23 and 9/24 for Fpn IRE (B) and eALAS IRE (C). Equilibrium dissociation constants were normalized to that of L-ferritin, presented as Krel ± SEM for at least three determinations for each IRE. (A) P-valueL-Ft, (B) P-valueFpn, and (C) P-valueeALAS refer to the comparison of the RNA of interest to the long wild-type IREs (L-ferritin and ferroportin, 66 nt; eALAS, 65 nt). (N.S.) Not significant. Nucleotide changes relative to wild type are circled.