anti-CD71 (human), Rabbit Monoclonal (RM384)

Cellular uptake of iron occurs via receptor-mediated endocytosis of ligand-occupied transferrin receptor into specialized endosomes. Two types of Transferrin receptors (TfRs) are known, TfR1 (CD71) and TfR2. The latter molecule has only recently been identified and its function remains unclear. In contrast, the role of TfR1 in binding transferrin and delivering Fe to cells is well known. TfR1 exists as an integral membrane homodimer that binds one transferrin molecule per monomer. Binding of transferrin to the TfR1 leads to receptor-mediated endocytosis and the endosome is the site where Fe is released from transferrin. Furthermore, acidification of the endosome by membrane bound proton pumps and the reduction of Fe(III) to Fe(II) are also involved in release and transport of this metal ion into the cell. Once released from transferrin, Fe then passes through the endosomal membrane via the divalent metal transporter 1. The uptake of Fe from transferrin is controlled by TfR1 expression that is modulated by intracellular Fe levels via iron-regulatory proteins. Transferrin receptor 1 is necessary for development of erythrocytes and the nervous system. Serum transferrin receptor (sTfR1) is used as a means of detecting erythropoietin (EPO) misuse by athletes and as a diagnostic test for anemias resulting from a number of conditions including rheumatoid arthritis, pregnancy, irritable bowel syndrome and in HIV patients. TfR1 as a potential new target in cases of human leukemia and lymphoma.