Figure 5

Alp14-driven growth rates of S. pombe MTs versus catastrophe rate and lifetime Two plots of the same data to show (A) Catastrophe rate and (B) Lifetime versus Alp14-driven MT growth rate. Filled data points show the mean plus end growth rate of individual MTs growing from surface-immobilized GMPCPP-stabilised MT seeds, with increasing growth rates driven by increasing concentrations of tip-tracking Alp14 as in Fig. 4C. The ambient concentrations of Alp14 used in the assays are colour coded. There is only a loose correlation of growth rate to ambient Alp14 concentration, because there is a large variation in the amount of Alp14 that loads to individual MTs. Open data points at high growth rates are from MTs that nucleated de novo during the assays. All data obtained at 6 μM tubulin, except for the open squares data points (encircled) which were obtained by reducing the tubulin concentration to 0.5 μM and increasing Alp14 concentration sufficiently to maintain growth at ~12 nm s⁻¹. Under these conditions, the growth rate is maintained at the expense of excess catastrophes.