The neck domain of myosin II primarily regulates the actomyosin kinetics, not the stepsize

Atsuko Hikikoshi Iwane, Hiroto Tanaka, Sayuri Morimoto, Akihiko Ishijima, Toshio Yanagida

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


In order to study the role of the neck domain of myosin in muscle contraction, we measured the steps of individual myosin II molecules engineered to have no neck domain (light chain-binding domain) by optical trapping nanometry. The actin filament and myosin cofilaments interacted on a glass surface to minimize the angle between them, and to minimize the interaction between myosin and the glass surface. The results showed that the average myosin stepsize did not change much when the neck domain was removed, but the sliding velocity decreased ∼fivefold. Furthermore, the duration of steps for neckless myosin was several times longer at saturated ATP concentration, indicating that the slower velocity was due to a slower dissociation rate of myosin heads from actin. From these data, we conclude that the neck domain of myosin-II primarily regulates the actomyosin kinetics, not the mechanics.

Original languageEnglish
Pages (from-to)213-221
Number of pages9
JournalJournal of Molecular Biology
Issue number2
Publication statusPublished - 2005 Oct 21
Externally publishedYes


  • Actin
  • Molecular motor
  • Muscle contraction
  • Myosin
  • Single molecule

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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