FIGURE 5:

Anti-catastrophe and rescue activity of Stu1-TOG2. (A) Representative kymographs of yeast αβ-tubulin (0.8 µM) growing from GTPγS-stabilized seeds (pseudocolored green). Microtubule dynamics were imaged using time-lapse DIC microscopy and show slow growth, rapid shrinking, frequent catastrophe, and no rescues. See C for quantification of the dynamics. (B) As above, but in the presence of Stu1-TOG2 (0.2 µM). The presence of Stu1-TOG2 leads to longer growth phases (reduced catastrophe) and elevated rescue (rescues are marked with *). (C) Quantification of the microtubule dynamics from A (in gray) and B (in red). From left to right: growing rates do not change substantially (control: 17.9 ± 0.2 µm/h, n = 245; +TOG2: 18.8 ± 0.3 µm/h, n = 126); shrinking rates are also little changed (control: 170 ± 8 µm/min, n = 11; +TOG2: 183 ± 12 µm/min, n = 18); catastrophe frequency decreases fourfold in the presence of TOG2 (control: 0.098 {0.094, 0.100} min⁻¹, n = 57, 160 catastrophes; +TOG2: 0.025 {0.024, 0.027} min⁻¹, n = 44, 38); rescue frequency increases in the presence of TOG2 (control: no rescues; +TOG2: 19 {18, 20} min⁻¹, n = 21, 16 rescues). Error bars on the scatter plots for growing and shrinking rates indicate overall mean and SD. Values reported for growth and transition frequencies are weighted average over two independent experiments. n gives the total number of observed events for growing and shrinking rates, and the number in each of two trials for the transition frequencies. For the transition frequencies, averages from each separate experiment are given in braces to provide a measure of experimental variation. Values reported for shrinking rates are from a single experiment. Errors reported for growth and shrinking rates are SEM.