Alternate fast and slow stepping of a heterodimeric kinesin molecule

Nat Cell Biol. 2003 Dec;5(12):1079-82. doi: 10.1038/ncb1067. Epub 2003 Nov 23.


A conventional kinesin molecule travels continuously along a microtubule in discrete 8-nm steps. This processive movement is generally explained by models in which the two identical heads of a kinesin move in a 'hand-over-hand' manner. Here, we show that a single heterodimeric kinesin molecule (in which one of the two heads is mutated in a nucleotide-binding site) exhibits fast and slow (with the dwell time at least 10 times longer than that of the fast step) 8-nm steps alternately, presumably corresponding to the displacement by the wild-type and mutant heads, respectively. Our results provide the first direct evidence for models in which the roles of the two heads alternate every 8-nm step.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Dimerization
  • Kinesins / chemistry*
  • Kinesins / physiology
  • Microtubules / physiology*
  • Models, Molecular
  • Molecular Conformation
  • Molecular Motor Proteins / chemistry*
  • Molecular Motor Proteins / physiology
  • Mutation / physiology
  • Protein Transport / physiology
  • Time Factors


  • Molecular Motor Proteins
  • Kinesins