The human hCTR1 gene was originally identified by its ability to complement a yeast mutant deficient in high-affinity copper uptake (Zhou, B., Gitschier, J., 1997. A human gene for copper uptake identified by complementation in yeast. Proc. Natl. Acad. Sci. USA 94, 7481-7486). Here, we have determined the DNA sequence of the exon-intron borders of the hCTR1 structural gene and report that the coding sequence is disrupted by three introns, all of which comply with the GT/AG rule. Furthermore, human fibroblasts, transfected with hCTR1 cDNA, were shown to have a dramatically increased capacity for (64)Cu uptake, indicating that the hCtr1 protein is functional in copper uptake in human cells. In contrast, no evidence was found for involvement of the hCTR2 gene product in copper uptake. Finally, we have identified a highly homologous processed pseudogene, hCTR1psi, which was localized to chromosome 3q25/26. The processed gene was found to be transcribed, but due to a frame shift mutation, it only had the potential to encode a truncated protein of 95 amino acid residues, and cells transfected with hCTR1psi DNA showed no increase of (64)Cu uptake.