Nucleocytoplasmic transport: cargo trafficking across the border.

Transport of macromolecules between the cytoplasm and the nucleus is mediated by at least three different classes of soluble transport receptors, members of the importin-beta protein family, the Mex67/Tap family and the small nuclear transport factor 2 (NFT2). All nuclear transport factors can bidirectionally traverse the nuclear pore complex through specific interactions with phenylalanine/glycine-rich nuclear pore complex components. Recent kinetic and structural analyses revealed novel insight into the details of these interactions. In addition, new biochemical and genetic studies have dramatically improved our understanding of ribosomal and messenger RNA export, unveiling a tight coupling between RNA processing and transport.