Rabbit Polyclonal antibody to CD71/TfR

Transferrin receptor 1 (CD71, TFRC) is a type II transmembrane receptor and carrier protein responsible for the uptake of cellular iron through receptor~mediated endocytosis. Neutral pH at the cell surface promotes binding of the iron~binding glycoprotein transferrin (Tf) to the CD71 receptor. The receptor~ligand complex enters the cell through receptor~mediated endocytosis and is internalized into an endosome. Relatively lower endosomal pH leads to a change in the local charge environment surrounding the iron~transferrin binding site and results in the release of iron. The receptor~ligand complex is recycled to the cell surface where transferrin dissociates from the CD71 receptor. Ubiquitously expressed transferrin receptor is continuously recycled and undergoes clathrin~mediated endocytosis regardless of ligand binding state. The interaction between receptor and ligand has been studied in detail. The helical domain of CD71 directly interacts with the transferrin C~lobe and induces a conformation change in Tf to facilitate the transport process. Interaction between the receptor CD71 and transferrin is mediated by the membrane protein hemochromatosis (HFE). HFE binds the α~helical domain of CD71, blocking formation of the CD71~transferrin complex and inhibiting iron uptake. In addition to binding transferrin, CD71 also interacts with H~ferritin at the cell surface and transports this intracellular iron storage protein to cellular endosomes and lysosomes. Additional studies indicate that the transferrin receptor is an evolutionarily conserved receptor for a number of arenaviruses and at least one retrovirus. Aberrant expression of CD71 is seen in a number of cancers, including thyroid carcinomas, lymphomas, and T~lineage leukemias, suggesting a possible therapeutic role for targeted inhibition of the transferrin receptor.