Biophysical Journal 71: 1235-1247 (1996)
© 1996 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Duke, T Articles by Leibler, S Search for Related Content PubMed PubMed Citation Articles by Duke, T Articles by Leibler, S

Motor protein mechanics: a stochastic model with minimal mechanochemical coupling.

Department of Physics, Princeton University, New Jersey 08544, USA.

ABSTRACT

A stochastic model for the action of motor proteins such as kinesin is presented. The mechanical components of the enzyme are 1) two identical head domains that bind to discrete sites on a microtubule and that are capable of undergoing a conformational change; and 2) an elastic element that connects each head to the rest of the molecule. We investigate the situation in which the strain dependence of the chemical reaction rates is minimal and the heads have independent biochemical cycles. The enzyme advances stochastically along a filament when one head detaches and diffuses to a new binding site, while the other head remains bound to the microtubule. We also investigate the case in which the chemical cycles of the heads are correlated so that the molecule shifts each head alternately. The predictions of the model are found to be in agreement with experimentally measured force-velocity relationships for kinesin-both when the force is applied externally and when the enzyme is loaded by a viscous drag. For reasonable values of the parameters, this agreement is quantitative. The molecular stepping characteristics observed in recent motility assays are also reproduced. A number of experiments are suggested that would provide a more stringent test of the model and help determine whether this simple picture is an appropriate description of motor proteins or whether models that include strain-dependent reaction rates or more complicated types of cooperation of the two heads need to be considered.

This article has been cited by other articles:

				C. M. Coppin, D. W. Pierce, L. Hsu, and R. D. Vale The load dependence of kinesin's mechanical cycle PNAS, August 5, 1997; 94(16): 8539 - 8544. [Abstract] [Full Text] [PDF]