Transferrin

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transferrin
Identifiers
Symbol	TF
HUGO	11740
Entrez	7018
OMIM	190000
RefSeq	NM_001063
UniProt	P02787
Other data
Locus	Chr. 3 q21

Transferrin is a blood plasma protein for iron ion delivery. Transferrin is a glycoprotein, which binds iron very tightly but reversibly. Although iron bound to transferrin is less than 0.1% (4 mg) of the total body iron, dynamically it is the most important iron pool, with the highest rate of turnover (25 mg/24 h). Transferrin has a molecular weight of around 80,000 and contains 2 specific high affinity Fe(III) binding sites. The affinity of transferrin for Fe(III) is extremely high (10^23 M^-1 at pH 7.4) but decreases progressively with decreasing pH below neutrality.

1 Transport mechanism
2 Immune system
3 Other effects
4 See also
5 External links

[edit] Transport mechanism

When a transferrin protein loaded with iron encounters a transferrin receptor on the surface of a cell, it binds to it and is consequently transported into the cell in a vesicle. The cell will acidify the vesicle, causing transferrin to release its iron ions. The receptor is then transported through the endocytic cycle back to the cell surface, ready for another round of iron uptake. Each transferrin molecule has the ability to carry two iron ions in the ferric form (Fe3+).

The gene coding for transferrin in humans is located in chromosome band 3q21.

Transferrin levels may be checked in iron deficiency, hemochromatosis and other iron overload disorders.

[edit] Immune system

Transferrin is also associated with the innate immune system. Transferrin is found in the mucosa and binds iron, thus creating an environment low in free iron, where few bacteria are able to survive.