Fig. 3: EB dimers connected by a flexible scaffold move processively and harness force from a growing microtubule tip.

a Schematics of EB3 ensembles on a 200 bp DNA scaffold. b Kymograph of a single DNA scaffold with two EB3 heterodimers tracking the tip of a growing microtubule. c (Left), Red points are run lengths of individual EB3 scaffolds. Blue points are growth distances of the microtubule tips that these scaffolds ran on. Corresponding tips and scaffolds are connected by lines. (Right) residency times of the scaffolds from the left (n = 162 for 2xEB3, n = 56 for 3xEB3). d Schematics of the experimental setup for measuring forces generated by EB3 scaffolds. e–h Individual examples of force traces for scaffolds with different numbers of EBs. Traces shown are smoothed to 20 Hz and fitted with logistic function (red line) to determine the force. In ‘e’ extracted force and slope are shown (\(F\) and \(\nu\)). 42 out of 200 beads tested showed detectable force generation. i Extracted forces plotted as a function of the number of EBs in the scaffold. Bars are mean and whiskers are standard deviation. Number of measurements left to right: n = 9, n = 9, n = 10, n = 7. On the right, experiment in which EB dimers were coupled directly to the streptavidin bead (No scaffold used. One bead has estimated > 170,000 EB binding sites). In ‘e–i’ 2x, 3x and 4x corresponds to single scaffolds with 2, 3 and 4 EB3 dimers respectively. Source data for this figure are provided as a Source Data file.