The cell consists of many different compartments, each of which carries out a special function. A network of transport pathways moves molecules between these compartments to reach their proper location. This process, called vesicular transport, is central to the cell’s ability to grow, divide and communicate with its external environment. Receptors are dependent on vesicular transport for reaching the cell surface, where they bind factors that are essential for the cell such as hormones and nutrients. An enormous number of human diseases, including cancer, diabetes and Alzheimer’s disease, result from defects in vesicular transport. A specialized group of proteins called adaptors coordinate the wide variety of transport events within the cell. Each adaptor recognizes its own set of molecules for transport and initiates the pathway that will take them to their final destination. Adaptors cannot work by themselves; many regulators cooperate with these complexes, guiding them to the correct location and activating them for cargo binding. Helen Burston is identifying the molecules that cooperate with Adaptor Protein Complex 3 (AP-3), an adaptor required for the formation and function of lysosomes, which are required for immunity, blood clotting, and brain function. This research will help develop a better understanding of defects in neurological function and immunity.