Genetic Analysis of Macromolecular Transport across the Nuclear Envelope (original) (raw)

bind at the cytoplasmic surface of the NPC [11, 12]. Numerous factors that promote movement of macro-Following binding, vectorial movement through the molecules in and out of the nucleus have now been pore complex is catalyzed by a host of factors. These identified. These include both soluble cytoplasmic and factors include a GTPase, termed Ran, and its various nucleoplasmic proteins and proteins of the nuclear regulators, including a GAP and an exchange factor pore complex (NPC). Genetic analyses of the nuclear [13][16]. In addition, proteins of the NPC are intitransport process in the model organism, the budding mately involved in the import process [18][19][20][21]. The acyeast Saccharomyces cerevisiae, have revealed retual manner by which GTP promotes import is under markable conservation of all of these factors. In addiintense study. However, the facts that the GAP, termed tion, important clues as to how these factors promote Rna1p, is located primarily in the cytoplasm [22] and the unique bidirectional movement across the NPC the exchange factor, termed Rcc1, is nuclear [23] prohave emerged from studies of yeast. We summarize the vide important clues around which various models characterization and genetic interactions of the soluhave been constructed and tested.