RECONSTITUTION OF NUCLEAR-PORE ASSEMBLY AND FUNCTION

Nuclear pore complexes are the vital communication links that permit t he regulated movement of macromolecules between the cytoplasm and nucl eus of a cell. As with many other complex cellular events, much of our understanding about pore dynamics and function comes from studying sy stems that faithfully reproduce these processes in vitro. Two systems have provided the bulk of our knowledge. The first system reconstitute s nuclear import into permeabilized cultured cells. Import is dependen t on exogenously added cytosol, and fractionation of this cytosol has led to the identification and characterization of most of the nuclear transport factors. The second system uses a nuclear reconstitution sys tem derived from Xenopus eggs to study transport and to assemble nucle ar pores from their component parts. This system has allowed the chara cterization of both individual pore components and distinct steps in t he pore assembly pathway.