Journal article
The force exerted by a single kinesin molecule against a viscous load
Biophysical journal, Vol.67(2), pp.766-781
08/1994
Handle:
https://hdl.handle.net/2376/116176
PMCID: PMC1225420
PMID: 7948690
Abstract
Kinesin is a motor protein that uses the energy derived from the hydrolysis of ATP to power the transport of organelles along microtubules. To probe the mechanism of this chemical-to-mechanical energy transduction reaction, the movement of microtubules across glass surfaces coated with kinesin was perturbed by raising the viscosity of the buffer solution. When the viscosity of the solution used in the low density motility assay was increased approximately 100-fold through addition of polysaccharides and polypeptides, the longer microtubules, which experienced a larger drag force from the fluid, moved more slowly than the shorter ones. The speed of movement of a microtubule depended linearly on the drag force loading the motor. At the lowest kinesin density, where dilution experiments indicated that the movement was caused by a single kinesin molecule, extrapolation of the linear relationship yielded a maximum time-averaged drag force of 4.2 +/- 0.5 pN per motor (mean +/- experimental SE). The magnitude of the force argues against one type of "ratchet" model in which the motor is hypothesized to rectify the diffusion of the microtubule; at high viscosity, diffusion is too slow to account for the observed speeds. On the other hand, our data are consistent with models in which force is a consequence of strain developed in an elastic element within the motor; these models include a different "ratchet" model (of the type proposed by A. F. Huxley in 1957) as well as "power-stroke" models.
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Details
- Title
- The force exerted by a single kinesin molecule against a viscous load
- Creators
- A J Hunt - Department of Physiology and Biophysics, University of Washington, Seattle 98195F Gittes - Department of Physiology and Biophysics, University of Washington, Seattle 98195J Howard - Department of Physiology and Biophysics, University of Washington, Seattle 98195
- Publication Details
- Biophysical journal, Vol.67(2), pp.766-781
- Academic Unit
- Physics and Astronomy, Department of
- Identifiers
- 99900548288101842
- Language
- English
- Resource Type
- Journal article