Iron is an essential element but possesses potential toxicity for aerobic lives.Ferritin,a large protein complex with high capacity of iron incorporation,can sequester iron in a bioavailable way.Mammalian ferritin is predominantly in the cytosol,with a minor portion found in plasma,whilein most insects including Drosophila melanogaster,ferritin is confined to the vacuolar secretory pathway and abundant in plasma.