The mitotic kinesin CENP-E is a processive transport motor.

In vivo studies suggest that centromeric protein E (CENP-E), a kinesin-7 family member, plays a key role in the movement of chromosomes toward the metaphase plate during mitosis. How CENP-E accomplishes this crucial task, however, is not clear. Here we present single-molecule measurements of CENP-E that demonstrate that this motor moves processively toward the plus end of microtubules, with an average run length of 2.6 +/- 0.2 mum, in a hand-over-hand fashion, taking 8-nm steps with a stall force of 6 +/- 0.1 pN. The ATP dependence of motor velocity obeys Michaelis-Menten kinetics with K(M,ATP) = 35 +/- 5 muM. All of these features are remarkably similar to those for kinesin-1-a highly processive transport motor. We, therefore, propose that CENP-E transports chromosomes in a manner analogous to how kinesin-1 transports cytoplasmic vesicles.