An improved optical tweezers assay for measuring the force generation of single kinesin molecules

Matthew P. Nicholas, Lu Rao, Arne Gennerich

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


Numerous microtubule-associated molecular motors, including several kinesins and cytoplasmic dynein, produce opposing forces that regulate spindle and chromosome positioning during mitosis. The motility and force generation of these motors are therefore critical to normal cell division, and dysfunction of these processes may contribute to human disease. Optical tweezers provide a powerful method for studying the nanometer motility and piconewton force generation of single motor proteins in vitro. Using kinesin-1 as a prototype, we present a set of step-by-step, optimized protocols for expressing a kinesin construct (K560- GFP) in Escherichia coli, purifying it, and studying its force generation in an optical tweezers microscope. We also provide detailed instructions on proper alignment and calibration of an optical trapping microscope. These methods provide a foundation for a variety of similar experiments.

Original languageEnglish (US)
Pages (from-to)171-246
Number of pages76
JournalMethods in Molecular Biology
StatePublished - 2014
Externally publishedYes


  • Escherichia coli
  • Force measurement
  • K560
  • Kinesin
  • Microtubules
  • Molecular motors
  • Optical trap alignment and calibration
  • Optical trapping
  • Optical tweezers
  • Protein purification
  • Pyranose oxidase
  • Single-molecule assays

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics


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