Fig. 1. Cell cycle-dependent localization of Cdh1p, Cdc20p and Cdc23p. (A) Wild-type cells (EY957) expressing the indicated GFP fusion proteins from the GAL promoter were grown at 30°C until mid-log phase, and analysed by GFP microscopy. Cells at different stages of the cell cycle are shown. The arrowheads point to Cdh1p–GFP localized to the mother bud neck. Note that Cdh1p is nuclear during G₁, but predominantly cytoplasmic during S phase, G₂ and mitosis. (B) Indirect immunofluorescence of HA3-Cdh1p expressed from the GAL promoter using 11HA antibodies. The arrowhead points to HA3-Cdh1p localized to the mother bud neck. (C) Nuclear recovery of Cdh1p–GFP was measured by FRAP as schematically represented in the upper panel. Nuclear recovery was measured in G₁ cells (squares), or in late mitosis (late M) during relocalization of Cdh1p (diamonds). The nuclear/cytoplasmic exchange rate was quantified as described in Materials and methods, and is shown as t_1/2 with SD. An unbleached nucleus was included as control (triangles).