Stores iron in a soluble, non-toxic, readily available form. Important for iron homeostasis. Has ferroxidase activity. Iron is taken up in the ferrous form and deposited as ferric hydroxides after oxidation. Also plays a role in delivery of iron to cells. Mediates iron uptake in capsule cells of the developing kidney (By similarity). (Microbial infection) Is unable to assume its function upon interaction with viral proteins, thereby increasing Fe concentration in the cytoplasm. This would inhibit the accumulation of reactive oxygen in host cells, leading to reduced apoptosis and increasing the survival of virus infected cell. 4 Fe(2+) + 4 H(+) + O2 = 4 Fe(3+) + 2 H2O Oligomer of 24 subunits. There are two types of subunits: L (light) chain and H (heavy) chain. The major chain can be light or heavy, depending on the species and tissue type. The functional molecule forms a roughly spherical shell with a diameter of 12 nm and contains a central cavity into which the insoluble mineral iron core is deposited (By similarity). (Microbial infection) Interacts with classical swine fever virus protein NS4B. (Microbial infection) Interacts with Porcine circovirus 2 ORF4 protein. Belongs to the ferritin family.