ABSTRACT
The Kinesin-5 family are homotetrameric, typically plus-end-directed motors with the ability to slide anti-parallel microtubules and to alter microtubule dynamics. Yeast Kinesin-5s display the fascinating ability to switch direction of motility. Kinesin-5 motors are unique in that they act as homotetramers, with pairs of catalytic motor domains located on opposite sides of a 60-nm-long rod-like mini-filament. Loop 5 of the Kinesin-5 motor domain is long compared with other kinesin families, typically consisting of 18 residues. A flexible 14- to 18-amino acid long neck linker immediately follows the motor domain and undergoes adenosine triphosphate- and microtubule-dependent docking onto the motor domain. The Kinesin-5 neck linker is longer than that of Kinesin-1, a trait that is suggested to contribute to the relatively low processivity of Kinesin-5 motors. The processivity of Kinesin-5s is relatively low. A truncated dimeric version of human Kinesin-5 takes on average approximately eight steps before detaching.
