Zinc is the second most abundant trace metal in the human body. It is an essential element, serving both a structural role, as in the formation of zinc fingers in DNA-binding proteins, and a catalytic role in metalloenzymes, such as pancreatic carboxypeptidases, alkaline phosphatases, various dehydrogenases, and superoxide dismutases. SLC30A4, or ZNT4, belongs to the ZNT family of zinc transporters. ZNTs are involved in transporting zinc out of the cytoplasm and have similar structures, consisting of 6 transmembrane domains and a histidine-rich cytoplasmic loop . The gene encodes a 430-amino acid protein that is homologous to Znt2 (SLC30A2) and Znt3 (SLC30A3). Znt4 was abundantly expressed in mammary epithelia and brain.