InterPro domain: IPR009078

Ferritin is one of the major non-haem iron storage proteins in animals, plants, and microorganisms. It is a multisubunit protein with a hollow interior, which contains a mineral core of hydrated ferric oxide, thereby ensuring its solubility in an aqueous environment [ 1 ]. Each subunit consists of a closed, four-helical bundle with a left-handed twist and one crossover connection.

This entry represents the ferritin-like superfamily. Proteins with this structure include ferritin and other ferritin-like proteins such as bacterioferritin (cytochrome b1) that binds haem between two subunits, non-haem ferritin, dodecameric ferritin homologue (DPS) that binds to and protects DNA, and the N-terminal domain of rubrerythrin that is found in many air-sensitive bacteria and archaea [ 2 ]. In addition, ribonucleotide reductase-like proteins show a similar structure to the ferritin-like fold; these di-iron carboxylate proteins constitute a diverse class of non-haem iron enzymes performing a multitude of redox reactions [ 3 ]. The superfamily also includes the alpha and beta subunits of methane monooxygenase hydrolase, delta 9-stearoyl-acyl carrier protein desaturase and manganese catalase.

1. Localized unfolding at the junction of three ferritin subunits. A mechanism for iron release? J. Biol. Chem. 273, 18685-8
2. X-ray crystal structures of reduced rubrerythrin and its azide adduct: a structure-based mechanism for a non-heme diiron peroxidase. J. Am. Chem. Soc. 124, 9845-55
3. Crystal structures of oxidized dinuclear manganese centres in Mn-substituted class I ribonucleotide reductase from Escherichia coli: carboxylate shifts with implications for O2 activation and radical generation. J. Biol. Inorg. Chem. 6, 315-23