 In particular, these shared features include cysteine residues involved in disulfide bond formation, histidine residues involved in copper binding, and residues involved in the binding of the iron substrate.The regulation of hephaestin expression and the protein's role in the larger picture of iron metabolism and homeostasis remain an active area of research.Some studies suggest mechanisms for local and systemic control of intestinal iron transport, in which high dietary iron intake and sufficient iron stores lead to down-regulation of DMT1, ferroportin (Ireg1) and hephaestin protein, thus minimizing iron absorption from the enterocytes into the circulation.