Figure 7.

The Effect of Microtubule Growth Velocity and EB1 Concentration on Pause Times and EB1 Intensity Decay Rates before Catastrophes

(A) Averaged microtubule end position aligned at the catastrophe time point (see Supplemental Experimental Procedures) at different tubulin concentrations and hence growth velocities (50 nM EB1-GFP). The gray lines indicate growth pauses before catastrophe (Supplemental Experimental Procedures).

(C) Normalized averaged EB1-GFP intensity-time profiles corresponding to (A). Solid lines are exponential fits to the data. The dashed and dotted horizontal lines give the average residual EB1-GFP intensity at catastrophe and error, respectively.

(B and D) As in (A) and (C), for varying EB1-GFP concentrations (20 μM tubulin). Note that the pause time at 50 nM EB1-GFP in (B) is comparable to the pause times shown in (A) at the same EB1-GFP concentration and different tubulin concentrations.

(E) Pause times (upper panel) and EB1-GFP decay times (lower panel) before catastrophe, extracted from (A)–(D), versus total maturation time (defined in the text).

(F) Average time until catastrophe (see Figure S7A) versus total maturation time.

(G) Schematic illustrating the change in microtubule end structure before a catastrophe. The orange-colored tubulins represent tubulins in the stabilizing B state; the green ovals represent bound EB1.

Between 44 and 90 catastrophes were averaged for each condition. Error bars are SE. See also Figure S7.