This course will cover the mechanisms of nucleocytoplasmic transport in eukaryotic cells. The nuclear pore complex of the nuclear envelope provides a selective barrier for macromoleculaes in a eukaryotic cell. Essentially all proteins found in the nucleus are transported into the nucleus in a directed fashion. In addition, all cytoplasmic RNAs, including mRNA, miRNAs, rRNA (as ribosomes) and tRNAs are exported in a highly regulated fashion. Most of these transport events are directed by a family of related proteins called karyopherins. These transport receptors promote transport through the highly hydrophobic channel of the nuclear pore complex. Remarkably, the mechanism of transport does not require energy. However, ATPases and GTPases provide directionality to the transport pathways. Finally, recent atomic structures are beginning to shed light on the molecular mechanisms that govern transport.