Measuring Molecular Forces Using Calibrated Optical Tweezers in Living Cells

Methods Mol Biol. 2017;1486:537-552. doi: 10.1007/978-1-4939-6421-5_21.


Optical tweezers have been instrumental in uncovering the mechanisms motor proteins use to generate and react to force. While optical traps have primarily been applied to purified, in vitro systems, emerging methods enable measurements in living cells where the actively fluctuating, viscoelastic environment and varying refractive index complicate calibration of the instrument. Here, we describe techniques to calibrate optical traps in living cells using the forced response to sinusoidal oscillations and spontaneous fluctuations, and to measure the forces exerted by endogenous ensembles of kinesin and dynein motor proteins as they transport cargoes in the cell.

Keywords: Biological materials; Cell mechanics; Dynein; Intracellular transport; Kinesin; Live-cell assays; Microtubules; Optical trap; Optical tweezers.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calibration
  • Cytoplasm
  • Elasticity
  • Macrophages / metabolism
  • Mice
  • Microscopy / methods*
  • Molecular Motor Proteins / chemistry*
  • Optical Tweezers*
  • Optics and Photonics / methods*
  • Viscosity


  • Molecular Motor Proteins