NMR and mutagenesis of human copper transporter 1 (hCtr1) show that Cys-189 is required for correct folding and dimerization

The human high-affinity copper transporter (hCtr1) is a membrane protein that is predicted to have three transmembrane helices and two methionine-rich metal binding motifs. As an oligomeric polytopic membrane protein, hCtr1 is a challenging system for experimental structure determination. The results of an initial application of solution-state NMR methods to a truncated construct containing residues 45-190 in micelles and site-directed mutagenesis of the two cysteine residues demonstrate that Cys-189 but not Cys-161 is essential for both dimer formation and proper folding of the protein.