Cu(I) binds to the C-terminal domain of copper transport protein hCtr1 and transfers to copper chaperone Atox1

The intracellular C-terminal domain of human copper transporter hCtr1 is crucial for copper transport and delivery in cells. However, the mechanism of copper acquisition and distribution is not fully understood. The copper binding to hCtr1 was studiedusing a C-terminal peptide (C8) through the methods of UV-vis, NMR and MS spectroscopies. The results show that cuprous ions exhibit high binding affinity to C8 (log K=16.6). C8 can bind with multiple copper ions, and the His and Cys residues in the HCH motif are the key binding sites, while an aspartate residue could also be involved in the copper coordination. Further investigation reveals that copper ions can transfer from C8 to the copper chaperone Atox1. These data provide detailed information on the copper binding to hCtr1 and help understand the copperdistributions in cells.