C. Divalent metal ion transporter
Ans – b). Ferroportin
Iron leaves the mucosal cell via a transport protein ferroportin, but only if there is free transferrin in plasma to bind to. Once transferrin is saturated with iron, any that has accumulated in the mucosal cells is lost when the cells are shed. Expression of the ferroportin gene is downregulated by hepcidin, a peptide secreted by the liver when body iron reserves are adequate. In response to hypoxia, anemia, or hemorrhage, the synthesis of hepcidin is reduced, leading to increased synthesis of ferroportin and increased iron absorption. As a result of this mucosal barrier, only ~10% of dietary iron is absorbed, and only 1 to 5% from many plant foods.