Molecular friction due to a small number of motor proteins in a Characean motility assay system

Yuki Kagawa, Yuuki Mizukami, Yoshimi Tsuchiya

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The observation of the actin-myosin sliding motion in in vitro motility assay system has contributed to the clarification of the driving force of motor proteins. Those studies have suggested that molecular friction in addition to hydrodynamical friction plays an important role in the sliding motion. However, it has not yet been discussed how the molecular friction takes part in the sliding motion due to a few motors or a single motor protein. This study, at first, has experimentally estimated the molecular friction in a Characean motility assay system using chemically modified Chara myosins. Next, we have constructed a Langevin equation for the sliding motion on the basis of the molecular level picture proposed by Tawada and Sekimoto. It has been found from the model that the molecular friction affects the sliding motion even when a small number of myosins interact with the actin filament. Last, we have discussed the molecular friction due to a small number of motor proteins quantitatively.

Original languageEnglish
Pages (from-to)1040-1048
Number of pages9
JournalJournal of the Physical Society of Japan
Issue number3
Publication statusPublished - 1999 Mar



  • Actin
  • Chara
  • In vitro motility assay
  • Molecular friction
  • Myosin
  • Sliding motion
  • Weak binding interaction

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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