SMART accession number:SM00094
Description: -
Interpro abstract (IPR001156):

Transferrins are eukaryotic iron-binding glycoproteins that control the level of free iron in biological fluids [(PUBMED:3032619)]. The proteins have arisen by duplication of a domain, 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.

Additional members of this family include inhibitor of carbonic anhydrase (ICA; mammals), major yolk protein (sea urchins), saxiphilin (frog), pacifastin (crayfish), and TTF-1 (algae). Most family members contain two transferrin-like domains of around 340 amino acids, the result of an ancient duplication event [(PUBMED:15621505)]. Each of the duplicated domains can be further divided into two subdomains that form a cleft inside of which the iron atom is bound in iron-transporting transferrin [(PUBMED:2585506)]. 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.

Human lactoferrin is a serine peptidase belonging to MEROPS peptidase family S60, clan SR. It is found at high concentrations in all human secretions, where it plays a major role in mucosal defence. Lactoferrin cleaves IgA1 protease at an arginine-rich region defined by amino acids RRSRRSVR and digests Hap at a similar arginine-rich sequence (VRSRRAAR). Ser259 and Lys73 form a catalytic dyad, reminiscent of a number of bacterial serine proteases.

GO process:cellular iron ion homeostasis (GO:0006879), iron ion transport (GO:0006826)
GO component:extracellular region (GO:0005576)
GO function:ferric iron binding (GO:0008199)
Family alignment:
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There are 1311 TR_FER domains in 768 proteins in SMART's nrdb database.

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