Figure 2. The loop reduces diffusion of Ndc80 trimers without affecting their end‐tracking.

• A
  Preparation of TMR‐labeled, streptavidin‐mediated Ndc80 trimers. See Appendix Fig S1 for more information.
• B–D
  TMR‐labeled Ndc80 trimers with (FL, blue) or without (ΔL, orange) the loop were added to taxol‐stabilized microtubules to measure their residence time (panel C) and one‐dimensional diffusion (panel D). Ndc80 trimers with and without the loop are shown. Scale bars: vertical (1,000 s), horizontal (5 μm).
• E
  One‐dimensional diffusion of Ndc80 trimers (with n indicated) on microtubules. Traces were split into segments of 60 s and averaged. Mean values (circles) and SEM (shaded area) are shown.
• F
  Kymographs of full‐length and loopless Ndc80 trimers (10 pM) that reside on dynamically growing and shortening microtubules. Trimers remain bound to the ends of shortening microtubules. Scale bars: vertical (100 s), horizontal (5 μm).
• G
  Distribution of initial brightness of end‐tracking Ndc80 trimers with full‐length (blue) or loopless (orange) Ndc80.
• H
  Fraction of Ndc80 trimers that switches from lateral microtubule binding to tracking shortening ends. Data from four repeats (total 140 events) for full‐length Ndc80 trimers (blue), and two repeats (total 158 events) for loopless Ndc80 trimers (orange). Horizontal lines indicate average values.
• I
  End‐tracking speed of full‐length (blue) and loopless (orange) Ndc80 trimers that follow shortening microtubule ends. Compared to Ndc80‐free shortening ends in the same field of views (gray). Horizontal lines indicate median values.

Source data are available online for this figure.