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. Author manuscript; available in PMC: 2013 Mar 3.
Published in final edited form as: Ann N Y Acad Sci. 2009 Oct;1177:30–38. doi: 10.1111/j.1749-6632.2009.05038.x

Figure 2.

Figure 2

Iron dependent regulation of the IRPs. In states of low iron, IRPs are capable of binding IREs in the 5′ or 3′ UTR in mRNAs of genes contributing to iron homeostasis. IRP-binding in turn blocks translation initiation or mRNA degradation, respectively. In states of high iron, IRP1 loses its IRE-binding activity following assembly of an iron sulfur cluster and conversion to a cytosolic aconitase. In contrast, IRP2 is polyubiquitinated and degraded by the proteasome under iron- and oxygen-replete conditions.