A depiction of the human FHC promoter region, containing the basal enhancer (B box), Sp1 binding site (A box), an inhibitory region (G-fer), Antioxidant Response Element (ARE), and TSA Responsive Element (LaVaute et al.) (A). Processes illustrated in B regulate translation of FHC mRNA. Iron Regulatory Proteins (IRP) 1 and 2 bind the stem-loop structure of the Iron Responsive Element (IRE) to inhibit translation and are inactivated by high levels of free iron. Mechanisms of iron-mediated IRP inactivation include a loss of IRE binding affinity (IRP1) and protein degradation (IRP2).