Transferrin is a bilobed glycoprotein. The polypeptide chain of transferrin is composed of two homologous lobes i.e N- and C- lobes. Each lobe is made of two domains N1, N2 and C1, C2 which are linked by a hinge. It has two specific sites for binding of Fe3+.
Transferrin is the major iron transporter protein that binds Fe(+3). The transferring-iron import system consists of a TonB dependent transporter (TbpA), and a lipoprotein co-receptor (TbpB) and both proteins work together in the transport of iron across the membrane.
