On the mechanism of iron sensing by IRP2: new players, new paradigms

Two iron regulatory proteins (IRP1 and IRP2) regulate translation and/or stability of mRNAs encoding proteins required for iron storage, acquisition and utilization. Rather than IRP2 directly sensing iron concentrations, iron has been shown to regulate the level of the SKP1-CUL1-FBXL5 E3 ubiquitin ligase protein complex, which is responsible for IRP2 degradation.