ABSTRACT
This chapter describes how the expression of these genes by iron is regulated without large-scale effects in their transcription. The genetic regulation of the transferrin receptor for acquiring iron and the ferritin subunits for its safe storage are each highly coordinated as a part of the cellular response to adapt to iron levels. The pathway by which iron is delivered from circulating transferrin to cells is mediated by the passage of the transferrin receptor and its bound ligand, ferrotransferrin, from the cell surface to sites within the cell. Cellular ferritin is the iron storage protein of all cells within which iron is oxidized to the ferric state as ferric oxyhydroxide. The cellular influx of iron downregulates the display of transferrin receptors on the cell surface by decreasing Transferrin Receptor protein synthesis. The chapter shows that iron can regulate the translation of ferritin, and possibly Erythroid 5-Aminolevulinate Synthase mRNAs, by a single IRE positioned upstream of the coding sequence.
