<p>Transferrins are a family of eukaryotic iron-binding glycoproteins that share the common function of controlling the level of free iron in biological fluids [<cite idref="PUB00001349"/>]. The transferrin family currently includes: </p><ul><li>Blood serotransferrin (siderophilin). </li> <li>Milk lactotransferrin (lactoferrin). </li><li>Egg white ovotransferrin (conalbumin). </li><li>Membrane-associated melanotransferrin.</li></ul> <p>Transferrins are proteins of 650 to 700 residues which have evolved from the duplication of a domain of around 340 residues. Each of the duplicated domains binds one atom of iron. Each iron atom is bound by four conserved residues: an aspartic acid, two tyrosines, and a histidine [<cite idref="PUB00003252"/>]. All of the cysteines in both domains are involved in intradomain disulphide bonds. </p><p>This entry contains three different signature patterns for transferrins. Each of them is centred on one of the iron-binding residue, respectively the two tyrosines and the histidine. Each of the signatures is present twice in each type of transferrins. </p> Transferrin family, iron binding site