Transferrin Receptor gene,also known as CD71, encodes a cell surface receptor necessary for cellular iron uptake by the process of receptor-mediated endocytosis. It is required for erythropoiesis and neurologic development.It binds to two molecules of transferrin and a serum iron-transport protein,and directs the cellular uptake of iron via receptor-mediated endocytosis. CD71 is expressed, typically at high levels, on all proliferating cells, reticulocytes and erythroid precursors. It is not expressed on resting leukocytes, but is upregulated upon activation of lymphocytes, monocytes and macrophages. A second transferrin receptor, TFR2, also mediates the uptake of transferrin-bound iron. Mutations in the TFR2 gene result in hereditary hemochromatosis type III (HFE3), an iron overloading disorder predominant in Caucasians.
