Xpo1p associates with spindle pole bodies in logarithmically growing cells and redistributes to kinetochores during SAC arrest. (A–D) Cells synthesizing Xpo1-GFP and Mtw1-RFP (Y3109) or Xpo1-GFP and Spc42-RFP (Y3101) were analyzed by epifluorescence microscopy after either logarithmic growth (A and B) or nocodazole-induced arrest (C and D). Note that the insets in B show a G1 cell. (E and F) A cdc26Δ mutant was introduced into Y3109 to produce Y3131. Cultures of these cells were shifted to 37°C, and the localization of Mtw1-RFP and Xpo1-GFP was assessed in the absence (E) and presence (F) of nocodazole. The arrows in C and F highlight colocalization of Xpo1-GFP and Mtw1-RFP, and the arrowheads in A and E point to kinetochores lacking Xpo1-GFP signal. The arrowheads in D indicate spindle poles devoid of Xpo1-GFP signal. (G) Quantification of Xpo1-GFP colocalization with either Spc42-RFP or Mtw1-RFP from the experiments presented in A–D. 30 cells were analyzed for each condition in each of three independent experiments, and results are presented as a mean with SD (error bars). (H) ChIP analysis was performed on cells producing Xpo1-GFP (Y3169) growing logarithmically (asynchronous [AS]) or arrested in nocodazole (+Noc). T, total chromatin used in each IP; M, mock minus antibody IP; α-GFP, anti-GFP antibody IP. Bars, 2 μm.