Serotransferrin

Serotransferrin is a glycoprotein found in the blood plasma of vertebrates. It is the primary protein responsible for transporting iron from its absorption sites in the small intestine to the bone marrow, liver, and other tissues where it is needed for cellular processes. Transferrin belongs to the transferrin family of proteins, which are characterized by their ability to bind and transport metal ions. Each molecule of serotransferrin can bind two ferric iron ions. This binding is crucial for maintaining iron homeostasis in the body, preventing both iron deficiency and iron overload. The iron-binding sites are located in two homologous lobes, each capable of chelating a ferric iron ion and a carbonate anion.

The synthesis of serotransferrin occurs mainly in the liver. Its production is regulated by factors such as iron levels and inflammation. When iron stores are low, the liver increases serotransferrin synthesis, leading to higher concentrations in the blood, which enhances iron uptake. Conversely, high iron levels tend to suppress its production. Serotransferrin plays a vital role in the innate immune system by making iron less available to invading microorganisms, which often require iron for their growth and proliferation. It is also implicated in the transport of other metal ions, though iron is its primary ligand. In clinical settings, measuring serotransferrin levels can provide insights into iron status and inflammatory conditions.