Figure 2

Localization patterns of PBIP1 and Plk1 during the cell cycle. (A), Asynchronously growing HeLa cells were costained with anti-Plk1 and anti-PBIP1 antibodies. Representative images from each stage of the cell cycle are shown. Note that, except G2, inverse correlation between PBIP1 and Plk1 localization is manifest. (B), Schematic diagram illustrating the fluctuation of PBIP1 and Plk1 fluorescence intensities at the centromeres/kinetochores during the cell cycle. During interphase, PBIP1 is tightly localized to centromeres (Red). A rise in the Plk1 level and activity (Blue) during early mitosis induces PBIP1 delocalization from the kinetochores, thus yielding an increased level of non-centromeric PBIP1 population (Green). The free Plk1 population from the p-T78 PBIP1 tether may interact with various PBD-binding proteins or substrates at or near the kinetochores.