Length control of microtubules by depolymerizing motor proteinsB. S. Govindan1, M. Gopalakrishnan1 and D. Chowdhury2
1 Harish-Chandra Research Institute - Chhatnag Road, Jhunsi, Allahabad 211019, India
2 Department of Physics, Indian Institute of Technology - Kanpur 208016, India
received 22 April 2008; accepted in final form 2 July 2008; published August 2008
published online 19 August 2008
In many intracellular processes, the length distribution of microtubules is controlled by depolymerizing motor proteins. Experiments have shown that, following non-specific binding to the surface of a microtubule, depolymerizers are transported to the microtubule tip(s) by diffusion or directed walk and, then, depolymerize the microtubule from the tip(s) after accumulating there. We develop a quantitative model to study the depolymerizing action of such a generic motor protein, and its possible effects on the length distribution of microtubules. We show that, when the motor protein concentration in solution exceeds a critical value, a steady state is reached where the length distribution is, in general, non-monotonic with a single peak. However, for highly processive motors and large motor densities, this distribution effectively becomes an exponential decay. Our findings suggest that such motor proteins may be selectively used by the cell to ensure precise control of MT lengths. The model is also used to analyze experimental observations of motor-induced depolymerization.
05.40.-a - Fluctuation phenomena, random processes, noise, and Brownian motion.
87.16.-b - Subcellular structure and processes.
87.16.Nn - Motor proteins (myosin, kinesin dynein).
© EPLA 2008