Condensin II is required for efficient loading of CENP-A. (A) Bar graph showing the CENP-A loading efficiency in the indicated extracts in two independent experiments. Bars represent mean ± SE. (B) Immunoblot analysis of increasing amounts of a mock-depleted extract (expressed as percentage of a 1.5-µl aliquot, lanes 1–5) and an extract depleted with anti-XCAP-D3 without (lane 6) or with 1:10 volume of affinity-purified condensin II (lane 7). (C) Bar graph showing the CENP-A loading efficiency in mock- and condensin II–depleted extracts with and without adding back purified condensin II. (D) Immunofluorescent staining of mitotic chromosomes assembled in mock- and condensin II–depleted extracts with antibodies against xHJURP (green) and CENP-A (red). DNA was counterstained with DAPI (blue). Bar, 10 µm. (E) Model to explain the role of xHJURP and condensin II in CENP-A dynamics. CENP-A and H3 nucleosomes are shown in green and red, respectively. Net incorporation of CENP-A will depend on the balance between addition of new CENP-A nucleosomes, a process in which xHJURP has a key role, and eviction of these nucleosomes. Condensin II prevents eviction of CENP-A nucleosomes but it is also required for their incorporation.