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Related Experiment Video

Updated: Feb 10, 2026

Functional Reconstitution and Channel Activity Measurements of Purified Wildtype and Mutant CFTR Protein

Functional Reconstitution and Channel Activity Measurements of Purified Wildtype and Mutant CFTR Protein

Published on: March 9, 2015

Kif15 functions as an active mechanical ratchet.

Toni McHugh¹, Hauke Drechsler¹, Andrew D McAinsh¹

¹Centre for Mechanochemical Cell Biology, Warwick Medical School, Gibbet Hill, Coventry CV4 7AL, United Kingdom.

Molecular Biology of the Cell

|May 18, 2018

Summary

Kinesin-12 (Kif15) motor protein mechanics are direction-dependent. Tpx2 binding stabilizes Kif15 on microtubules, enabling spindle extension but resisting compression.

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Area of Science:

Cell Biology
Biophysics
Molecular Motors

Background:

Kinesin-12 (Kif15) is crucial for bipolar spindle assembly in human cells.
Understanding Kif15's mechanical properties is key to elucidating its role in cell division.

Purpose of the Study:

To investigate the single-molecule mechanics of Kif15 under varying load conditions and nucleotide states.
To determine the influence of the binding partner Tpx2 on Kif15's microtubule interactions.

Main Methods:

Utilized optical trap force-ramp experiments to measure single Kif15 molecule behavior.
Analyzed Kif15's processivity, step frequency, and detachment rates under hindering and assisting loads.
Examined Kif15-Tpx2 complex dynamics on microtubules.

Main Results:

Kif15 exhibits limited processivity (<~10 steps) under hindering loads, stalling at 6 pN.
Under assisting loads, Kif15 detaches rapidly, even in the AMPPNP nucleotide state.
Tpx2 binding locks Kif15 onto microtubules, irrespective of load direction.

Conclusions:

Kif15's mechanical behavior is highly sensitive to the direction of applied force.
Tpx2 acts as a crucial regulator, stabilizing Kif15-microtubule interactions.
Kif15 functions as a mechanical ratchet in the central spindle, facilitating extension while opposing compression.