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. Author manuscript; available in PMC: 2011 May 1.
Published in final edited form as: Semin Cell Dev Biol. 2010 Jan 28;21(3):248–254. doi: 10.1016/j.semcdb.2010.01.015

Figure 3. Microtubule length-dependent regulation of microtubule length by motor-depolymerases.

Figure 3

The ability of a motor-depolymerases to affect microtubule length in a length-dependent manner is derived from the distance the motor can travel during its association with the microtubule track. For a processive motor, this distance is proportional the velocity of the motor and the amount of time it spends attached to the microtubule [71]. For a motor that relies on lattice based diffusion, such as MCAK, this is likely dependent on diffusion length which is proportional to the amount of time the motor dwells on the microtubule and its diffusion coefficient [69]. The diffusion length for MCAK is less than 1 µm while that for the processive kinesin-8 is ~ 8 µm. Microtubules longer than the motor’s typical travel length will collect the most motors at their tips, increasing the chance of a catastrophe (A). Motors that bind the microtubule too far from the ends will fall off before reaching them and not influence catastrophe frequency. In B, shorter microtubules will not collect as many motors and therefore will have fewer motors at their tips reducing the chance of catastrophe.