Ran GTPase regulates Mad2 localization to the nuclear pore complex.
In yeast and mammalian cells, the spindle assembly checkpoint proteins Mad1p and Mad2p localize to the nuclear pore complex (NPC) during interphase. Deletion of MAD1 or MAD2 did not affect steady-state nucleocytoplasmic distribution of a classical nuclear localization signal-containing reporter, a nuclear export signal-containing reporter, or Ran localization. We utilized cells with conditional mutations in the yeast Ran GTPase pathway to examine the relationship between Ran and targeting of checkpoint regulators to the NPC. Mutations that disrupt the concentration of Ran in the nucleus displaced Mad2p but not Mad1p from the NPC. The displacement of Mad2p in M-phase cells was correlated with activation of the spindle checkpoint. Our observations demonstrate that Mad2p localization at NPCs is sensitive to nuclear levels of Ran and suggest that release of Mad2p from NPCs is closely linked with spindle assembly checkpoint activation in yeast. This is the first evidence indicating that Ran affects the localization of Mad2p to the NPC.
Quimby
B Booth
BB
Laboratory of Gene Regulation and Development, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-5431, USA. quimbyb@mail.nih.gov
Arnaoutov
Alexei
A
Dasso
Mary
M
D000818:Animals; D001692:Biological Transport; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D006224:Cricetinae; D017930:Genes, Reporter; D064246:Mad2 Proteins; D009154:Mutation; D019913:Nuclear Localization Signals; D022022:Nuclear Pore / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D020931:ran GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
D018797:Cell Cycle Proteins; C501382:MAD1 protein, S cerevisiae; C577695:MAD2 protein, S cerevisiae; D064246:Mad2 Proteins; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D020931:ran GTP-Binding Protein