Transferrin

Transferrins are <a href="/facts/Glycoprotein/bKPzzW7m">glycoproteins</a> found in <a href="/facts/Vertebrate/tT54FSTT">vertebrates</a> which bind and consequently mediate the transport of <a href="/facts/Iron/QK1JYy8E">iron</a> (Fe) through <a href="/facts/Blood_plasma/oHuwwugG">blood plasma</a>. They are produced in the <a href="/facts/Liver/Rtp4Fk2b">liver</a> and contain binding sites for two <a href="/facts/Iron(III)/TMrSskIt">Fe3+</a> ions. Human transferrin is encoded by the TF <a href="/facts/Gene/e1swwPY6">gene</a> and produced as a 76 <a href="/facts/Dalton_(unit)/IMATU3vf">kDa</a> glycoprotein.
Transferrin <a href="/facts/Glycoprotein/bKPzzW7m">glycoproteins</a> 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). Transferrin has a molecular weight of around 80 <a href="/facts/Atomic_mass_unit/IMATU3vf">kDa</a> and contains two specific high-affinity <a href="/facts/Fe(III)/TMrSskIt">Fe(III)</a> binding sites. The affinity of transferrin for Fe(III) is extremely high (<a href="/facts/Association_constant/MA7wKe5v">association constant</a> is 1020 M−1 at pH 7.4) but decreases progressively with decreasing <a href="/facts/PH/RnSv8D7y">pH</a> below neutrality. Transferrins are not limited to only binding to iron but also to different metal ions. These glycoproteins are located in various bodily fluids of vertebrates. Some invertebrates have proteins that act like transferrin found in the <a href="/facts/Hemolymph/6tHgrY6c">hemolymph</a>.
When not bound to iron, transferrin is known as "apotransferrin" (see also <a href="/facts/Apoenzyme/DSI1Fh7y">apoprotein</a>).

Transferrin open-in-new

Transferrin