<p>This family represents ferritin and related proteins. Ferritin is a major non-haem iron storage protein in animal, plants and microorganisms [<cite idref="PUB00016335"/>]. Iron is required by most organisms, but is potentially toxic due to its reactivity, which is counteracted by sequestering it into ferritin. Ferritin consists of a 4-helical bundle core, and contains a bimetal-ion centre in the middle of the bundle. Other proteins with this structure include: haem-containing bacteriferritins; rubrerythrin, which appears to have a role in anaerobic detoxification pathway for reactive oxygen species [<cite idref="PUB00016336"/>]; Dps (DNA-binding proteins from starved cells) used in bacteria for iron storage-detoxification; and CRD1 (AcsF), which is required for the maintenance of photosystem I [<cite idref="PUB00015567"/>].</p>