The nuclear pore complex.

Over the past years, significant progress has been made both in the analysis of the structural and molecular organization of the nuclear pore complex (NPC) and the mechanism of nuclear transport. In this minireview, I will focus on some of the recent developments in this field. Structural studies employing high resolution EM have revealed a detailed view of the three-dimensional organization of the NPC. In addition, an isolation procedure which yields highly enriched NPCs from yeast has given insight into the molecular complexity of the NPC organization. By biochemical, immunological and genetic approaches, a series of novel pore proteins were identified. Exploiting yeast as a genetic system, several mutants defective in nuclear import of proteins and export of RNA were selected. By in vitro nuclear transport assays, soluble cytoplasmic factors including NLS (nuclear localization sequence) binding proteins and heat shock proteins required for nuclear accumulation were found. The aim of the future research must be to put these various components of the NPC and nuclear transport machinery in a topological and functional context.