A processive single-headed motor: Kinesin superfamily protein KIF1A

A single kinesin molecule can move "processively" along a microtubule for m ore than 1 micrometer before detaching from it. The prevailing explanation far this processive movement is the "walking model," which envisions that e ach of two motor domains (heads) of the kinesin molecule binds coordinately to the microtubule. This implies that each kinesin molecule must have two heads to "walk" and that a single-headed kinesin could not move processivel y. Here, a motor-domain construct of KIF1A, a single-headed kinesin superfa mily protein, was shown to move processively along the microtubule for more than 1 micrometer. The movement along the microtubules was stochastic and fitted a biased Brownian-movement model.