Microtubule catastrophe under force: mathematical and computational results from a Brownian ratchet model.

In the intracellular environment, the intrinsic dynamics of microtubule filaments is often hindered by the presence of barriers of various kind, such as kinetochore complexes and cell cortex, which impact their polymerisation force and dynamical properties such as catastrophe frequency. We present a theoretical study of the effect of a forced barrier, also subjected to thermal noise, on the statistics of catastrophe events in a single microtubule as well as a 'bundle' of two parallel microtubules. For microtubule dynamics, which includes growth, detachment, hydrolysis and the consequent dynamic instability, we employ a one-dimensional discrete stochastic model.

Temporal cooperativity of motor proteins under constant force: insights from Kramers' escape problem.

The microtubule-bound motors kinesin and dynein differ in many respects, a striking difference being that while kinesin is known to function mostly alone, dynein operates in large groups, much like myosinV in actin. Optical tweezer experiments in vitro have shown that the mean detachment time of a bead attached to [Formula: see text] kinesins under stall conditions is a slowly decreasing function of [Formula: see text], while for dyneins, the time increases almost linearly with [Formula: see text]. This makes dynein a team worker, capable of producing and sustaining a large collective force without detaching.