As the sole points of passage between the nucleus and the cytoplasm for macromolecules such as proteins, nuclear pore complexes form gateways that regulate the import and export of cargo to the nucleus. Cylinder-shaped and embedded in the nuclear envelope, NPCs determine what macromolecules are allowed to cross and ensure that the cargo proceeds in the right direction. The NPC is one of the largest multiprotein complexes in the cell. Because of its size, it was thought that as many as 200 proteins, called nucleoporins or nups, would be found to contribute to its architecture. Recent research published in the Feb. 21 issue of the Journal of Cell Biology by two Rockefeller University laboratories and a laboratory at the University of Alberta in Canada, provides significant insights into this important organelle.
Cell biologists can now enjoy the riches of our post-genomic era.
About four years ago, while a research associate in Blobel's lab, Michael Rout, now an assistant professor and head of the Laboratory of Cellular and Structural Biology, embarked on a project to obtain a comprehensive inventory of the proteins in the NPC to better understand how the NPC functions in transport across the nuclear envelope. Rather than starting from single components of the NPC and working outward, the team sought to identify and characterize all the components together. This then allowed them to produce a comprehensive picture of the nuclear pore complex. A major problem the team had to confront was sorting through these proteins to find the real NPC components. To characterize the NPC, Rout and his colleagues took yeast cells, separated the nuclei from the cytoplasm and then removed the NPCs from the nuclear envelope to produce an NPC-enriched solution.