Ferritin subunit - molecular model

The iron storage molecule ferritin consists of 24 subunits arranged in a spherical shell around a central cavity. Excess free iron is toxic and each ferritin molecule stores up to 4500 iron atoms inside its cavity as an insoluble and harmless iron (III) hydroxide. This is on of the subunits coloured in rainbow colours, ranging from red at the N-terminal start of the chain to purple at the C-terminal end of the chain.