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Ferroportin-1, also known as solute carrier family 40 member 1 (SLC40A1) or iron-regulated transporter 1 (IREG1), is a protein that in humans is encoded by the SLC40A1 gene. [5] Ferroportin is a transmembrane protein that transports iron from the inside of a cell to the outside of the cell.
Upon release into the bloodstream, Fe 3+ binds transferrin and circulates to tissues. In contrast, ferroportin is post-translationally repressed by hepcidin, a 25-amino acid peptide hormone. The body regulates iron levels by regulating each of these steps.
Iron-binding proteins are carrier proteins and metalloproteins that are important in iron metabolism [1] and the immune response. [2] [3] Iron is required for life.Iron-dependent enzymes catalyze a variety of biochemical reactions and can be divided into three broad classes depending on the structure of their active site: non-heme mono-iron, non-heme diiron , or heme centers. [4]
Human transferrin is encoded by the TF gene and produced as a 76 kDa glycoprotein. [7] [8] Transferrin glycoproteins bind iron tightly, but reversibly. Although iron bound to transferrin is less than 0.1% (4 mg) of total body iron, it forms the most vital iron pool with the highest rate of turnover (25 mg/24 h).
Another player assisting ferroportin in effecting cellular iron export is GAPDH. [47] A specific post translationally modified isoform of GAPDH is recruited to the surface of iron loaded cells where it recruits apo-transferrin in close proximity to ferroportin so as to rapidly chelate the iron extruded. [48]
Iron is transported by transferrin whose binding site consists of two tyrosines, one aspartic acid and one histidine. [22] The human body has no controlled mechanism for excretion of iron. [ 23 ] This can lead to iron overload problems in patients treated with blood transfusions , as, for instance, with β- thalassemia .
Ferritin is a much larger protein than transferrin and is capable of binding several thousand iron atoms in a nontoxic form. Siderophores are unable to directly mobilise iron from ferritin. In addition to these two classes of iron-binding proteins, a hormone, hepcidin, is involved in controlling the release of iron from absorptive enterocytes ...
In HEK 293 cells, Q248H was as predisposed to the activities of hepcidin-25 as wild type ferroportin. [27] Ferroportin Q248H also unregulated the expression of transferrin receptor-1 in the same way as wild type. This indicates the ferroportin Q248H is associated with mild clinical phenotype or causes iron disorder in the presence of other factors.