The primary protein responsible for iron homeostasis is:
Transferrin is a glycoprotein synthesized in the liver having a central role in the body's metabolism of iron. Each mole of transferrin can transpo two moles of ferric iron into circulation to sites where iron is required. Free iron is toxic, but when associated with transferrin, this toxicity is greatly diminished. When bound to transferrin, iron can be directed to cells where it is needed. Many cells have transferrin receptors and upon binding, the transferrin-receptor complex is internalized. The acidic pH of the lysosome causes the iron to disassociate from transferrin. Iron-free transferrin is then recycled to the cell surface along with its receptor where then it re-enters the circulation. Ceruloplasmin is a major copper carrier of the body and is also synthesized in the liver. Metallothioneins are found in many cells and can bind copper, zinc, cadmium and mercury. Ferritin is an intracellular iron-binding protein. It does not play a role in iron metabolism or transpo, and its function is to prevent ionized iron from reaching toxic levels within cells. Haptoglobin is a plasma glycoprotein that binds extracorpuscular hemoglobin. This function of haptoglobin is to prevent free hemoglobin from being lost through the kidneys since the haptoglobin-hemoglobin complex is too large to pass through the glomerulus. Ref: Beutler E. (2010). Chapter 42. Disorders of Iron Metabolism. In J.T. Prchal, K. Kaushansky, M.A. Lichtman, T.J. Kipps, U. Seligsohn (Eds), Williams Hematology, 8e.
Ceruloplasmin
Metallothionein
Transferrin
Ferritin