Beauty. Reference 1.

24 subunuits of4 a-helix bundles

Like an iron malted milk ball!

Fe3+Ox(OH)y core

One bundle

Fe3+O(OH)

Fe2+ oxid

Fe2+ exit

C4

C4

C3

C3

At pH 7, [Fe3+] = 10-18 M

Ferritin manages to concentrate ferric ion to mM concentrations (10-3 M).Lack of gene for ferritin lethal.

The reaction:

2000 Fe2+(H2O)6 + O2 1000 Fe3+—O-O—Fe3+ 2000 Fe3+(H2O)6 + H2O2

fast, ms slow, min or hrs Enters at C3 pores; in subunits ‘translocating mineral precursor’

Fe3+2O3 (H2O)1000 + 5000 H+

Exits from C3 pores

ferroxidase

Ferroxidase in H subunits (H for heart, NOT heavy!)

How and where iron exits from ferritin for cellular use is uncertain. Proline substitution for conserved leucine 134 (L134P) allowed normal assembly but increased iron exit rates. X-ray crystallography of H-L134P ferritin revealed localized unfolding at the 3-fold axis, also iron entry sites, consistent with shared use sites for iron exit and entry. The junction of three ferritin subunits appears to be a dynamic aperture with a "shutter" that cytoplasmic factors might open or close to regulate iron release in vivo.

Localized unfolding at the junction of three ferritin subunits. A mechanism for iron release?Takagi, H., Shi, D., Ha, Y., Allewell, N.M., Theil, E.C. (1998) J.Biol.Chem. 273: 18685-18688

Someone let the organometallic chemists out … and look what happened..

Apo-ferritin (apo-Fr) mutants are used as scaffolds to accommodate palladium (allyl) complexes. Various coordination arrangements of the Pd complexes are achieved by adjusting the positions of cysteine and histidine residues on the interior surface of the apo-Fr cage. ..