Ezra Burstein, M.D., Ph.D., Professor and Chief of the Division of Digestive and Liver Diseases at UT Southwestern is co-author of a research paper discussing copper as an essential transition metal for all eukaryotes. In mammals, intestinal copper absorption is mediated by the ATP7A copper transporter, whereas copper excretion occurs predominantly through the biliary route and is mediated by the paralog ATP7B.