The time course for increased IRP binding activity in response to iron deprivation. (A) Secondary structure of the FTL IRE used for the EMSA and the location of two deletions (ΔC) that inhibit IRP interactions. (B) Representative EMSA indicating the complexes formed between the radiolabeled FTL IRE and the extracts prepared from cells grown under the indicated iron-poor or iron-rich conditions. A 20-fold molar excess of unlabeled wild-type (wt) IRE but not the IRE with the ΔC mutation effectively competes out the interaction. (C) Quantitation of the IRE–IRP complex formed during iron deprivation relative to the nontreated cells. All error bars represent ±SEM of three biological replicates.
