Low iron concentrations promote increased levels of transferrin receptor, to increase iron intake into the cell. Thus, transferrin receptor maintains cellular iron homeostasis.
TfR production in the cell is regulated according to iron levels by iron response/regulatory element binding protein (IRE-BP), also referred to as Iron Regulatory Protein (IRP). When not bound to iron, this protein binds to the hairpin like structure (IRE) that is in the 3' UTR of the TfR receptor. Once binding occurs, degradation of mRNA of IRE is inhibited.
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