Analysis of IRE motifs bound by IRP1, IRP2, or both IRPs. (A) Bioinformatic prediction of IRE motifs in IRP1 and IRP2 target mRNAs, IRP1-specific target mRNAs and IRP2-specific target mRNAs. (B) Motif distribution of novel IREs (also see supplemental Table 3). Motif number and percentage (motif n. and motif %) are shown in the 3 IRP-target mRNAs lists. IREs without a mismatch or a 3′ bulge are depicted in blue, IREs with a mismatch are in red, and IREs with a 3′ bulge are shown in green. (C) Enrichment of IRE motifs in IRP-target mRNAs. After normalization for n19 multiple IRE options in each IRE type, observed and percentage expected frequencies of IRE motifs were calculated (χ² test, 1 df) and statistically significantly overrepresented motifs are shown. Red font, cross sign “x” or bracket cross sign “(x)” indicate differences compared with the canonical motif 1 IRE sequence. The cross sign or bracket cross sign indicate mismatches.