title: Measuring Molecular Forces Using Calibrated Optical Tweezers in Living Cells.
abstract: 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.
authors.affiliation: Department of Bioengineering, McGill University, 817 Sherbrooke ST. West, 270 Macdonald Engineering, Montreal, QC, Canada, H3A 0C3. adam.hendricks@mcgill.ca.
authors.forename: Adam G
authors.initials: AG
authors.lastname: Hendricks
authors.affiliation: Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.|Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Yale E
authors.initials: YE
authors.lastname: Goldman
mesh_terms: D000818:Animals; D002138:Calibration; D003593:Cytoplasm; D004548:Elasticity; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008853:Microscopy / Q000379:methods*; D020409:Molecular Motor Proteins / Q000737:chemistry*; D052898:Optical Tweezers; D055095:Optics and Photonics / Q000379:methods*; D014783:Viscosity
chemical_list: D020409:Molecular Motor Proteins
keywords: Biological materials; Cell mechanics; Dynein; Intracellular transport; Kinesin; Live-cell assays; Microtubules; Optical trap; Optical tweezers