InterPro domain: IPR001156

Transferrins are eukaryotic iron-binding glycoproteins that control the level of free iron in biological fluids [ 1 ]. Evidence suggests that members of the TF family arose from the duplication and fusion of two homologous domains, with each duplicated domain binding one iron atom. Members of the family include blood serotransferrin (siderophilin); milk lactotransferrin (lactoferrin); egg white ovotransferrin (conalbumin); and membrane-associated melanotransferrin. Family members that do not bind iron have also been discovered, including inhibitor of carbonic anhydrase (ICA), which strongly binds to and inhibits certain isoforms of carbonic anhydrase [ 2 ].

This entry represents the transferrin-like domain, which can be further divided into two subdomains that form a cleft inside of which the iron atom is bound in iron-transporting transferrin [ 3 ]. The iron-coordinating residues consist of an aspartic acid, two tyrosines and a histidine, as well as an arginine that coordinates a requisite anion. In addition to iron and anion liganding residues, the transferrin-like domain contains conserved cysteine residues involved in disulphide bond formation.

1. Iron transport and storage. Eur. J. Biochem. 164, 485-506
2. The structure and evolution of the murine inhibitor of carbonic anhydrase: a member of the transferrin superfamily. Protein Sci. 19, 1616-26
3. Structure of human lactoferrin: crystallographic structure analysis and refinement at 2.8 A resolution. J. Mol. Biol. 209, 711-34