Figure 4.

The sequential centrosome complementation assay reveals that full-length maskin needs to be exposed to extract to be functional, whereas the TACC domain of maskin can complement centrosomes independent of extract. (A) Schematic diagram of the sequential complementation assay. Salt-stripped centrosomes are incubated with extract as before. However, the extract is washed away before the centrosomes are incubated with recombinant protein. The recombinant protein is then washed away and the centrosomes are challenged with purified bovine tubulin as before. (B) Quantification of centrosome activity in the sequential assay, expressed as the number of asters found in 50 randomly chosen microscope fields. Centrosomes were incubated with recombinant maskin or truncation mutants as indicated below the graph. The graph represents three independent experiments (indicated by circles).