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

• Published in: The EMBO journal Vol. 22; no. 5; pp. 1067 - 1074
• Main Authors: Yajima, Junichiro, Edamatsu, Masaki, Watai-Nishii, Junko, Tokai-Nishizumi, Noriko, Yamamoto, Tadashi, Toyoshima, Yoko Y.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 03.03.2003; Blackwell Publishing Ltd; Oxford University Press
• Subjects: Adenosine Triphosphate - metabolism; Amino acids; Animals; chromosome movement; Chromosomes - metabolism; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Humans; Kinesin - genetics; Kinesin - metabolism; kinesin-like protein; Microscopy - methods; microtubule motor protein; Microtubules - metabolism; mitosis; Molecular Motor Proteins - metabolism; polar ejection force; Recombinant Fusion Proteins - metabolism
• ISSN: 0261-4189; 1460-2075
• 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 ∼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.