Nucleocytoplasmic transport enters the atomic age

Nucleocytoplasmic transport occurs through nuclear pore complexes (NPCs) an d is mediated by saturable transport receptors that shuttle between the nuc leus and cytoplasm. Our understanding of the molecular interactions underly ing this process has improved dramatically as a result of the elucidation o f the crystal structures of several nuclear transport factors either alone or in a complex with other components of the nuclear transport machinery. F urthermore, a conserved family of proteins, which is distinct from the well characterized family of importin beta -like nuclear export receptors, is i mplicated in the export of messenger RNA to the cytoplasm.