The divalent metal transporter (DMT1) is a 12-transmem-brane domain protein responsible for dietary iron uptake in the duodenum and iron acquisition from transferrin in peripheral tissues. The transmembrane domain 4 (TM4) of DMT1 has been shown to be crucial for its biological function. Here we report the 3D structure and topology of the DMT1-TM4 peptide by NMR spectroscopy with simulated annealing calculations in membrane-mimetic environments, . 2,2,2-trifluoroethanol and SDS micelles. The 3D structures of the peptide are similar in both envi-ronments, with nonordered and flexible N- and C-termini flanking an ordered helical region. .
