Nucleocytoplasmic shuttling of the Cdc42p exchange factor Cdc24p.
Cdc24p, the GDP/GTP exchange factor for the regulator of actin cytoskeleton Cdc42p, localizes to sites of polarized growth. Here we show that Cdc24p shuttles in and out of the yeast nucleus during vegetative growth. Far1p is necessary and sufficient for nuclear accumulation of Cdc24p, suggesting that its nuclear import occurs via an association with Far1p. Nuclear export is triggered either by entry into the cell cycle or by mating pheromone. As Far1p is degraded upon entry into the cell cycle, cell cycle-dependent export of Cdc24p occurs in the absence of Far1p, whereas during mating similar export kinetics indicate that a Cdc24p-Far1p complex is exported. Our results suggest that the nucleus serves as a store of preformed Cdc24p-Far1p complex which is required for chemotropism.
Nern
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Division of Cell Biology, MRC Laboratory of Molecular Biology, Cambridge, CB2 2QH, United Kingdom.
Arkowitz
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RA
D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002467:Cell Nucleus / Q000502:physiology* / Q000648:ultrastructure; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D003593:Cytoplasm / Q000502:physiology / Q000648:ultrastructure; D004171:Diploidy; D005656:Fungal Proteins / Q000378:metabolism; D005838:Genotype; D020662:Guanine Nucleotide Exchange Factors; D006238:Haploidy; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D012097:Repressor Proteins; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism*
C073594:CDC24 protein, S cerevisiae; D018797:Cell Cycle Proteins; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; C081353:FAR1 protein, S cerevisiae; D005656:Fungal Proteins; D020662:Guanine Nucleotide Exchange Factors; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D020764:cdc42 GTP-Binding Protein