Regulation of translation of mammalian ferritin and transferrin mRNAs by iron-response element binding proteins.

Ferritin is a cytosolic protein that binds iron ions and prevents accumulation of toxic levels of Fe2+/Fe3+. However when Fe is limiting, ferritin poses a problem – it competes for Fe with iron-requiring enzymes. Mammalian cells therefore modulate the synthesis of ferritin – expressed under excess Fe, repressed under Fe scarcity. The transferrin receptor (a cell surface protein responsible for Fe uptake into cells) shows reciprocal regulation of synthesis to that of ferritin.