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 themetaphase plate during mitosis. How CENIP-E accomplishes this crucial task, however, is not clear. Here we present single-molecule measurements of CENIP-E that demonstrate that this motor moves processively toward the plus end of microtubules, with an average run length of 2.6 +/- 0.2 lim, in a hand-over-hand fashion, taking 8-nm steps with a stall force of 6 0.1 pN. The ATIP dependence of motor velocity obeys Michaelis-Menten kinetics with K-M,K-ATP = 35 +/- 5 mu M. All of these features are remarkably similar to those for kinesin-l-a highly processive transport, motor. We, therefore, propose that CENP-E transports chromosomes in a manner analogous to how kinesin-1 transports cytoplasmic vesicles.