Fig. 5. The C-terminal domain of Siz1 is sufficient for cell-cycle-dependent binding to the bud neck. (A) Diagram of GFP fusions containing parts of the C-terminal domain of Siz1. Ability to localize to the bud neck is indicated. (B) Fluorescence microscopy of nocodazole-arrested siz1 cells containing GFP fusions as illustrated in A. Bar, 5 µm. (C) Lysates of siz1 cells containing GFP fusions were analyzed by SDS-PAGE and immunoblotting with an antibody against HA. Note that fusions that fail to localize to the bud neck are present in quantities comparable to those that do. Lane g was from the same exposure of the same blot, but was spliced to remove extraneous lanes. (D) siz1 Cdc3-HA cells containing the indicated Siz variants were analyzed as in Fig. 4C. Unmodified Cdc3-HA is indicated, and SUMO-Cdc3 species are indicated by open square brackets. An asterisk indicates a cross-reacting band.