Stochastic dynamics of microtubules: A model for caps and catastrophes

We introduce and solve a phenomenological model for the so-called catastrophes, the abrupt transitions from the growing to the shrinking state of microtubules. The model may explain existing experimental results and resolve some long-standing apparent contradictions. In particular, the model reproduces observed catastrophe rates and waiting times for catastrophes upon sudden dilution. It may also explain why recent experiments fail to measure the GTP content in growing microtubules and provides a mechanism for so-called coupled hydrolysis.