Load-dependent release limits the processive stepping of the tetrameric Eg5 motor.
Tetrameric motor proteins of the Kinesin-5 family are essential for eukaryotic cell division. The microscopic mechanism by which Eg5, the vertebrate Kinesin-5, drives bipolar mitotic spindle formation remains unknown. Here we show in optical trapping experiments that full-length Eg5 moves processively and stepwise along microtubule bundles. Interestingly, the force produced by individual Eg5 motors typically reached only approximately 2 pN, one-third of the stall force of Kinesin-1. Eg5 typically detached from microtubules before stalling. This behavior may reflect a regulatory mechanism important for the role of Eg5 in the mitotic spindle.
Korneev
Mikhail J
MJ
Department of Physics and Astronomy, Vrije Universiteit, de Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands.
Lakämper
Stefan
S
Schmidt
Christoph F
CF
D000818:Animals; D016547:Kinesins / Q000737:chemistry / Q000502:physiology*; D008870:Microtubules / Q000737:chemistry / Q000502:physiology*; D009038:Motion; D052898:Optical Tweezers; D029867:Xenopus Proteins / Q000737:chemistry / Q000502:physiology*; D014982:Xenopus laevis
C088335:KIF11 protein, Xenopus; D029867:Xenopus Proteins; D016547:Kinesins