Structural basis for promotion of duodenal iron absorption by enteric ferric reductase with ascorbate.

Dietary iron absorption is regulated by duodenal cytochrome (Dcytb), an integral membrane protein that catalyzes reduction of nonheme Fe by electron transfer from ascorbate across the membrane. This step is essential to enable iron uptake by the divalent metal transporter. Here we report the crystallographic structures of human Dcytb and its complex with ascorbate and Zn.