Schematic representation of the regulation of gene expression by iron http://www.rndsystems.com/heme/hhnews/hh697a1.html
An iron responsive element (IRE) is a nucleotide sequence that forms a stem loop structure with the ability to bind
specific iron binding proteins (IBP) - enzymatically inactive aconitase
The affinity of the IBP for the IRE is greater in the absence of iron