Self-organization of microtubules and mitotic kinesins. (A) Self-organization of microtubules and XCTK2: time course of the formation of microtubule asters in the presence of 100 nM mCherry-XCTK2 and 20 µM tubulin. (left) Epifluorescence images of mCherry-XCTK2 and Cy5-tubulin taken at the indicated times in the individual color channels and as merged images. (right) Time course of organization monitored by image parameters: total contrast (top) for mCherry-XCTK2 images (green) and Cy5-microtubule images (red) as calculated by the standard deviation from the mean; colocalization (bottom) of mCherry-XCTK2 and Cy5-microtubule signals as calculated by Pearson’s correlation. (B) Self-organization of microtubules and Eg5. (left) Early (t1) and late (t2) example images illustrating the development of self-organization with Eg5-GFP (green) and Cy5-microtubules at the concentrations indicated. (right) The time course of self-organization is monitored by the standard deviation, which is indicative of contrast (left), and Pearson’s correlation coefficient, which is indicative of colocalization (right), for the color channels as indicated. The time points of the example images to the left are indicated in the curves with arrows. (C) Self-organization of microtubules and chimeric Kin-Eg5. Composition of the figure is as described in B. All experiments were performed in assay buffer with 50 mM KCl. a.u., arbitrary unit. Bars, 50 µm.