Transferrin: Proteins and Enzymes

Human Transferrin is synthesized as a 698 amino acid (aa) precursor that is divided into a 19 aa signal sequence plus a 679 aa mature segment that contains 19 intrachain disulfide bonds. Apo-Transferrin (iron-free) initially binds iron at the C-terminus, followed by iron binding at the N-terminus to form Holo-Transferrin (diferric-Transferrin). Holo-Transferrin will interact with the type I Transferrin receptor (TfR) on the surface of cells where it is internalized into acidified endosomes.