High affinity copper uptake protein 1 (Ctr1) is a protein that in humans is encoded by the SLC31A1 gene. Copper is an element essential for life, but excessive copper can be toxic or even lethal to the cell. Therefore, cells have developed sophisticated ways to maintain a critical copper balance, with the intake, export, and intracellular compartmentalization or buffering of copper strictly regulated. The 2 related genes ATP7A (MIM 300011) and ATP7B (MIM 606882), responsible for the human diseases Menkes syndrome (MIM 309400) and Wilson disease (MIM 277900), respectively, are involved in copper export. In S. cerevisiae, the copper uptake genes CTR1, CTR2, and CTR3 have been identified, and in human the CTR1 and CTR2 (MIM 603088) genes have been identified.