Figure 3. Kinesin‐2 motors differentiate between the microtubule and axoneme surface to take processive steps.

Tracking of the fluorescently labeled head domains KLP3A and KLP11 of the heterodimeric kinesin‐2 motors at limiting ATP concentrations. Note the corresponding colors in upper and lower panels.

• A, B
  The step size distribution centered around ˜13 nm when walking on microtubules. Together with the double‐exponential decay of the dwell times (E, F), these results support a hand‐over‐hand type stepping of the respective motors.
• C, D
  Tracking on axonemes increased step size distribution to ˜16 nm which is consistent with protofilament tracking.
• E, F
  Double‐exponential decay of the dwell times and raw stepping data with detected steps.
• G, H
  Double‐exponential decay of the dwell times again argues for a hand‐over‐hand stepping mechanism on axonemes.

Data information: (E–H) Steps are shown with the detected stepping pattern in red and the calculated step size in nm. Scale bars are 5.04 s (10 frames) wide and 10 nm high. The respective step sizes are fit to a normal distribution (x is mean, and μ is width of the distribution). Dwell times are fit to a double‐exponential distribution (± confidence interval). See Fig EV1 for more step data and Appendix Fig S7 for the respective kymographs. A two‐sample t‐test has confirmed the statistical significance of the difference between the step size distributions on microtubules versus axonemes (P‐values of 3e‐5 for KLP11/20 and 0.05 for KLP3A/B, respectively).