In humans, the 68-residue Cu chaperone Atox1 picks up Cu that has entered the cell via CTR1 and delivers the metal to cytoplasmic metal-binding domains in ATP7A and ATP7B (also called Menkes and Wilson disease proteins), two homologous multi-domain P1B-type ATPases located in the trans-Golgi network. This evidence concerns the gene ATOX1 and Wilson disease.