Proposed mechanism for iron uptake/release by ferritin. Proposed mechanism for iron uptake/release by ferritin. (A) Iron (Fe) enters through a pore in the apoferritin protein cage structure (Fn(0)), forming an iron-ferritin complex (FeFn
) through a reversible process. (B) A series of redox reactions lead to iron incorporation into the mineral core of ferritin (Fn(1)). After n incorporation steps, the Ferritin species Fn(n)is obtained (C) Iron can be released from the mineral core through redox and transport processes. (D) Ferritin molecules can also be proteolytically degraded, returning their entire iron content to the cLIP during this process.