Copper (Cu2+) is essential for many important biological processes such as mitochondrial oxidative phosphorylation, detoxification of free radicals, iron metabolism and neurotransmiter synthesis. Too much influx results in cell poisoning. In humans, there are two member of the SLC31 gene family that are implicated in copper transport. The human gene SLC31A1 encodes human copper transporter 1, hCTR1 and is ubiquitiously expressed, with highest levels seen in the liver.. It was first identified by functional complementation in ctr1-deficient yeast (Zhou B and Gitschier J, 1997). hCTR1 exists as a homotrimer at the plasma membrane of cells (De Feo CJ et al, 2007) and is responsible for high-affinity copper uptake (Lee J et al, 2002). The second gene product, hCTR2, has not be characterized yet.