Transferrin (human) ELISA Kit (10x96T)

Transferrin (Tf) is a blood plasma protein for iron delivery. Transferrin functions to deliver iron to cells via a receptor-mediated endocytotic process as well as to remove toxic free iron from the blood and to provide an antibacterial, low-iron environment. Tf protein contains 679 amino acid residues and has a molecular weight of ~79 kD, having 2 specific high affinity Fe(III) binding sites. The molecule is stabilized by 19 intra-chain disulfide bonds and is protected by three carbohydrate side chains. Although iron bound to transferrin is less than 0.1% (4 mg) of the total body iron, it is the most important iron pool, with the highest rate of turnover (25 mg/24 h). When a Tf protein loaded with iron encounters a transferrin receptor (TfR) on the surface of a cell it binds to it and is consequently transported into the cell by endosomes. ATP-dependent proton pumps then force H+ ions into the endosomes reducing the pH to 5.5, thus promoting iron release and conformational change of the receptor enabling apo-transferrin to remain bound. The binding characteristics of the apo-Tf–TfR complex are such that the apo-Tf is released only once the complex reaches the cell surface. Cells expressing large amounts of TfR are correspondingly competent in securing iron from Tf. Rapidly proliferating cells, as in malignancy, generally express TfR1 abundantly. Several studies have shown a link between Tf polymorphism and susceptibility to disease. These include the rare autosomal recessive disorder atransferrinemia, cardiovascular disease (CVD) and Alzheimer’s disease. Transferrins are iron binding transport proteins which can bind two Fe3+ ions in association with the binding of an anion, usually bicarbonate. It is responsible for the transport of iron from sites of absorption and heme degradation to those of storage and utilization. Serum transferrin may also have a further role in stimulating cell proliferation.