Figure 2.

Cellular iron metabolism. (A) When the cellular iron levels are low, IRPs bind to the 5’ IREs of FPN1 and FT mRNA, resulting in translation repression. Additionally, IRPs bind to 3’ IREs in TFR1 mRNA to stabilize the DMT1 mRNA and increase TFR1 protein synthesis. These two effects can increase intracellular iron. (B) When the cellular iron levels are high, IRP1 converts to cytosolic aconitase and IRP2 is degraded, preventing IRP1 and IRP2 from binding to the IREs of these mRNAs. This permits unimpeded translation of FPN1 and FT and fosters degradation of DMT1 and TFR1 mRNA, leading to decreased cytosolic iron.