Influence of molecular motors on the motion of particles in viscoelastic media

SEBASTIÁN BOUZAT

PHYSICAL REVIEW E - STATISTICAL PHYSICS, PLASMAS, FLUIDS AND RELATED INTERDISCIPLINARY TOPICS

American Physical Society

Año: 2014 vol. 89 p. 62707 - 6270714

1063-651X

We study theoretically and by numerical simulations the motion of particles driven by molecular motors ina viscoelastic medium representing the cell cytoplasm. For this, we consider a generalized Langevin equationcoupled to a stochastic stepping dynamics for the motors that takes into account the action of each motor separately.In the absence of motors, the model produces subdiffusive motion of particles characterized by a power-law scalingof the mean square displacement versus the lag time as t α , with 0 < α < 1, similar to that observed in cells. Ourresults show how the action of the motors can induce a transition to a superdiffusive regime at large lag timeswith the characteristics of those found in experiments reported in the literature. We also show that at small lagtimes, the motors can act as static crosslinkers that slow down the natural subdiffusive transport. An analysis ofpreviously reported experimental data in the relevant time scales provides evidence of this phenomenon. Finally,we study the effect of a harmonic potential representing an optical trap, and we show a way to approach to amacroscopic description of the active transport in cells. This last point stresses the relevance of the molecularmotors for generating not only directed motion to specific targets, but also fast diffusivelike random motion.