KARYOPHERINS AND KISSING COUSINS

In eukaryotic cells, a regulated flux of molecules between the cytopla sm and the nucleus maintains two very different environments while all owing the controlled exchange of macromolecules necessary for their in dividual functions. Molecules entering or leaving the nucleus we nucle ar localization signals or nuclear export signals to pass through sele ctive channels in the nuclear envelope formed by nuclear pore complexe s. The recognition of signal-bearing cargo, its interaction with the n uclear pore complex and its translocation through the pore complex are mediated by soluble transport factors. Recently, the list of potentia l transport factors has grown rapidly, suggesting a previously unantic ipated level of complexity for nuclear transport.