The human chromokinesin Kid is a plus end-directed microtubule-based motor

EMBO J. 2003 Mar 3;22(5):1067-74. doi: 10.1093/emboj/cdg102.


Kid is a kinesin-like DNA-binding protein known to be involved in chromosome movement during mitosis, although its actual motor function has not been demonstrated. Here, we describe the initial characterization of Kid as a microtubule-based motor using optical trapping microscopy. A bacterially expressed fusion protein consisting of a truncated Kid fragment (amino acids 1-388 or 1-439) is indeed an active microtubule motor with an average speed of approximately 160 nm/s, and the polarity of movement is plus end directed. We could not detect processive movement of either monomeric Kid or dimerizing chimeric Kid; however, low levels of processivity (a few steps) cannot be detected with our method. These results are consistent with Kid having a role in chromosome congression in vivo, where it would be responsible for the polar ejection forces acting on the chromosome arms.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Animals
  • Chromosomes / metabolism
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Humans
  • Kinesin / genetics
  • Kinesin / metabolism*
  • Microscopy / methods
  • Microtubules / metabolism*
  • Molecular Motor Proteins / metabolism*
  • Recombinant Fusion Proteins / metabolism*


  • DNA-Binding Proteins
  • KIF22 protein, human
  • Molecular Motor Proteins
  • Recombinant Fusion Proteins
  • Adenosine Triphosphate
  • Kinesin