Table 1.

Effects of 2ME2 on the dynamic instability of steady-state MAP-free microtubules in vitro

[2ME2] (μmol/L)
042050
Parameter
    Growth rate (μm/min)0.52 ± 0.060.43 ± 0.030.3 ± 0.030.23 ± 0.02
    Growth length (μm)1.3 ± 0.21.2 ± 0.20.8 ± 0.10.8 ± 0.1
    Shortening rate (μm/min)28.0 ± 3.426.5 ± 3.918.3 ± 4.2*
    Shortening length (μm)6.9 ± 0.84.4 ± 0.84.7 ± 0.81.4 ± 0.9
    Catastrophe frequency (min−1)0.16 ± 0.050.13 ± 0.040.10 ± 0.030.02 ± 0.01
    Rescue frequency (min−1)0.9 ± 0.51.4 ± 0.70.6 ± 0.30.4 ± 0.2
    Dynamicity (μm/min)1.51.10.570.14
Percentage (%) of time spent:
    Growing88.684.473.951.3
    Shortening4.24.05.03.7
    Paused7.211.621.245.0
  • NOTE: Values in bold are significant at ≥99% confidence interval by Student's t test. Catastrophe and rescue frequency and dynamicity are calculated from the population of microtubules and thus statistical analysis cannot be done on these variables.

  • * Shortening events were rare at this concentration and, thus, the shortening rate could not be accurately calculated.