STOCHASTIC DYNAMICS OF MICROTUBULES - A MODEL FOR CAPS AND CATASTROPHES

We introduce and solve a phenomenological model for the so-called cata strophes, the abrupt transitions from the growing to the shrinking sta te of microtubules. The model may explain existing experimental result s and resolve some long-standing apparent contradictions. In particula r, the model reproduces observed catastrophe rates and waiting times f or catastrophes upon sudden dilution. It may also explain why recent e xperiments fail to measure the GTP content in growing microtubules and provides a mechanism for so-called coupled hydrolysis.