Regulation of Iron Homeostasis Occurs by Controlling the Amount That

Regulation of iron homeostasis occurs by controlling the amount that circulates in the serum as well as the amount contained within cells. One mechanism that plays a role in this homeostasis is iron-mediated control of the level of the intracellular iron-binding protein ferritin. Which of the following represents the mechanism of iron regulation of ferritin levels?

A) binding of iron to ferritin leads to secretion of the complex from cells and subsequent excretion in the urine
B) ferritin exists as a tetramer and when iron binds, the affinity for additional iron atoms increases
C) iron binds an additional protein that acts as a regulator of ferritin mRNA translation, high iron leads to increased translation and thus increased iron-binding capacity
D) when excess iron binds to ferritin it decreases the half-life of the protein allowing the iron to be released to the plasma and excreted