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Updated: Aug 13, 2026
12:26
Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
Published on: May 3, 2018
A phosphorylation switch governs KIF11's mechanical output during mitosis
Amila Šemić1, Babu J N Reddy2,3, Joseph M Muretta4
1Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405.
Summary
Src-family kinases phosphorylate KIF11, a motor protein essential for cell division. This phosphorylation regulates KIF11
Area of Science:
- Cell Biology
- Molecular Biology
- Biophysics
Background:
- Kinesin-5 motor protein (KIF11) is vital for mitotic spindle assembly and chromosome segregation.
- Src-family kinases phosphorylate KIF11, but the functional impact on its motor activity is not well understood.
Purpose of the Study:
- To investigate the mechanistic role of KIF11 phosphorylation at tyrosine 211 (Y211) in regulating motor function and spindle dynamics.
- To elucidate how Src-mediated phosphorylation impacts KIF11's interaction with microtubules and force generation.
Main Methods:
- Utilized phospho-mimetic (Y211E) and nonphosphorylatable (Y211F) KIF11 mutants.
- Employed biochemical assays, optical trapping, Förster resonance energy transfer (FRET), and fluorescence recovery after photobleaching (FRAP).
- Performed experiments in human cells to assess spindle formation and dynamics.
Main Results:
- Y211 phosphorylation significantly slows KIF11 neck-linker docking, reducing motor velocity and force generation under load.
- Expression of Y211E impairs bipolar spindle formation and decreases spindle pole separation velocity in human cells.
- Y211F mutation shortens steady-state spindle length, and Y211E accelerates motor turnover on spindle microtubules.
Conclusions:
- Src-mediated phosphorylation at Y211 acts as a rheostat, tuning KIF11 mechanochemistry and spindle assembly dynamics.
- This phosphorylation links cancer-relevant kinase signaling to mitotic force generation, impacting cell division.
- Understanding KIF11 phosphorylation provides insights into mitotic regulation and potential therapeutic targets.
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