FIGURE 4.

PA-GFP-HURP molecules photoactivated at the pole zone (A) Left: Schematic representation of photoactivation experiments in cells co-expressing PA-GFP-HURP and mCherry-tubulin. A 2 μm-wide area perpendicular to the spindle long axis (green stripe) was used to photoactivate PA-GFP-HURP molecules. Middle: mCherry-tubulin signal was used as a spatial reference to photoactivate PA-GFP-HURP molecules at the pole zone and register moving spindles during data processing. Right: Representative images PA-GFP-HURP molecules at different timepoints post photoactivation. Scale bar denotes 5 μm. (B) Left: Representative pole to pole fluorescence intensity profiles showing the distribution of the photoactivated PA-GFP-HURP molecules near the poles at different timepoints post photoactivation. The $t=0\mathit{sec}$ represents the first timepoint post photoactivation. Right: Representative plot showing the center of fluorescence distribution over time, fitted by a second order polynomial to calculate PA-GFP-HURP poleward velocity.