Laboratoire de Physique Théorique
Toulouse - UMR 5152

We investigate a simple model of microtubule dynamics in which a microtubule evolves by : (i) attachment of guanosine triphosphate (GTP) to its end at rate lambda, (ii) irreversible conversion of GTP to guanosine diphosphate (GDP) at rate 1, and (iii) detachment of GDP from the microtubule end at rate mu. As a function of these elemental rates, a microtubule can grow steadily or its length can fluctuate wildly. A master equation approach is developed to characterize these rich features. For mu=0, we find the exact tubule and GTP cap length distributions, as well as power-law length distributions of GTP and GDP islands. For mu=oo, we find the average time between catastrophes, where the microtubule shrinks to zero length, and the size distribution of avalanches (sequence of consecutive GDP detachment events).

work in collaboration with T. Antal, P. Krapivsky, B. Chakraborty, and M. Mailman