Background:Transferrin receptor protein 1(TfR1) also known as (Cluster ofDifferentiation71) (CD71) is aproteinthat in humans is encoded by theTFRCgene. TfR1 is required for iron delivery fromtransferrinto cells. TfR1 is a transmembrane glycoprotein composed of two disulfide-linked monomers joined by two disulfide bonds. Each monomer binds one holo-transferrin molecule creating an iron-Tf-TfR complex which enters the cell by endocytosis.