Figure 1.

Iron homeostasis. (A) Iron absorption. Fe³⁺ is reduced to Fe²⁺ by duodenal cytochrome B (Dcytb) and is transported from enteral lumen into the enterocyte by the divalent metaltrasporter-1 (DMT-1). Iron is transported by the ferroportin (FPN) to the circulation, after oxidization by hephaestin and binding to transferrin (Tf) (B) Cellular iron uptake takes place via the transferrin receptors (TfR) on the membrane of the cell and iron is internalized and released from Tf with the help of DMT-1 (C) The hepcidin is produced mainly in the liver after activation of the BMP/SMAD pathway via the interaction of transferrin with TfR2, protein HFE and the co-receptor hemojuvelin (HJV)

BMPR, bone morphogenetic protein receptor, HAMP, hepcidin antimicrobial protein.