Fig. 3.

Iron entry, oxidation, mineralization and reutilization. 1 Fe²⁺ enters the dodecamer via the N-terminal pores. 2 Fe²⁺ binds to the ferroxidase site and 3 is oxidized to Fe³⁺. 4 Fe³⁺ moves to the nucleation site. 5 Mineralization starts with the formation of FeOOH at the nucleation site. 6 Iron is reutilized by reducing FeOOH back to Fe²⁺ and 7 transported back to cytosol through N-terminal pores in response to cellular needs. i Fe²⁺ flowing to the cavity might also get oxidized on the surface of the growing mineral. ii Iron transport out of the protein might also occur via the C-terminal pores