The trafficking of macromolecules between the nucleus and cytoplasm is tightly regulated. Molecules must be first brought to the nuclear pore complex (NPC) by a set of specific adapter proteins. The steps that follow as the complex translocates through the NPC are poorly understood. To further understand these processes, I will utilize a novel in vitro system to look at transport through single NPCs. The advantage of this system is the access to single NPCs This allows for the reconstitution of transport using isolated factors. Initially, this system will be used to address basic questions regarding the poorly understood export of ribosomal subunits and the signal recognition particle. This system will also be applied to answering questions regarding the adapters and the proteins that compose the NPC itself.