Species of Origin: Purified frome rat serum. Transferrin is a single polypeptide chain glycoprotein and is a member of the iron binding family of proteins. It has a molecular weight of 77 kDa and a serum concentration range of 1800 to 2700 mg/L. It is synthesized in the liver and consists of two domains each having a high affinity reversible binding site for Fe3+. Iron is transported in blood and interstitial fluids to sites of use and disposal. Iron/transferrin is essential in hemoglobin synthesis and for certain types of cell division. Serum concentration rises in iron deficiency and pregnancy and falls in iron overload, infection and inflammatory conditions. The function of transferrin is to transport iron from the intestine, reticuloendothelial system, and liver parenchymal cells to all proliferating cells in the body. In addition to its function in iron transport, this protein may also have a physiologic role as granulocyte/pollen binding protein (GPBP) involved in the removal of certain organic matter/allergens from serum.