How does membrane trafficking control and co-ordinate the complex signaling pathways in the brain? Normal signaling depends on accurate localization of signaling receptors in specific regions of the cell, and trafficking plays a critical role in controlling this localization. Despite this obvious significance, we still know very little about the protein machineries that mediate trafficking of signaling receptors, the regulatory events that control these protein machineries, and the functional consequences of these regulatory events. Research in the lab addresses fundamental questions in these areas using G protein-coupled signaling receptors (GPCRs) important in drug addiction as model signaling receptors.