text: Mutation of the HFE gene can cause this element to build up in the body.
full_question: Mutation of the HFE gene can cause this element to build up in the body. The protein conalbumin, from egg whites, binds to this element. Regulation of this element is controlled by stem loops known as this element's namesake response element. The enzyme that converts citrate to isocitrate contains a central cluster that has four atoms of this metal. Aconitase is a member of a family of proteins named for this element and sulfur. Cytochromes and catalase contain a prosthetic group in which this metal coordinates with a tetrapyrrole ring to help bind oxygen. This element, which is transported by transferrin and ferritin, is deficient in the most common type of anemia. For 10 points, name this metal that is found in the heme group of hemoglobin.
first_sentence: Mutation of the HFE gene can cause this element to build up in the body.