Gene expression in eukaryotes requires the exchanges of macromolecules between the cytoplasm and nucleus. Changes in growth, developmental state, cell cycle and viral infection all affect the type of molecules exchanged in a cell. Nuclear pore complexes (NPCs), spanning both sides of the fused nuclear membrane, are the structures through which all movement occurs. Therefore, understanding NPC structure and assembly is critical in understanding nuclear/cytoplasmic communication and is the long-term objective of this research. Toward this end, a fluorescence- based genetic strategy will be employed in yeast to identify factors required for NPC assembly. The role of identified factors in the assembly process will be elucidated using a variety of microscopy studies and biochemical methods. Finally, biochemical and genetically interacting factors will be identified. Together, these experiments will address the fundamental questions regarding the biogenesis and assembly of the NPC.