An increasing number of human diseases have been attributed to mutations that result in the mistargeting of essential proteins. The signals responsible for the targeting membrane proteins in the biosynthetic and endocytic pathways are of particular interest to my laboratory. In addition to studying the basic cell biology of protein trafficking within the cell, we examine the trafficking and function of the proteins implicated in hemochromatosis, the most common hereditary disease of people of European ancestry. Four proteins have been implicated in this iron overload disease. Malfunctioning of these proteins results in the abnormal accumulation of iron in the body. We are examining the intracellular trafficking of these proteins and how they participate in the control of iron uptake and egress.