Fig. 4.

The Aur-A catalytic domain alone is sufficient to allow formation of bipolar spindle, but additional N-terminal sequences are required to restore the correct timing of mitotic entry and proper chromosome alignment. (A) Schematic of Aur-A proteins used in add-back experiments. (B) Mock- or Aur-A-depleted extracts were supplemented with nuclei (500 per μl) and rhodamine-labeled tubulin. Aur-A proteins or buffer were added to the Aur-A-depleted extract. Samples were analyzed as in Fig. 2. (C and D) The percentage of spindle structures and chromosome alignment was averaged from three independent experiments. At each time point, >100 spindle structures were counted. (E) Representative spindle structures. (Scale bar, 10 μm.)