Reversible movement of switch 1 loop of myosin determines actin interaction

Bálint Kintses, Máté Gyimesi, David S. Pearson, Michael A. Geeves, Wei Zeng, Clive R. Bagshaw, András Málnási-Csizmadia

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39 Citations (Scopus)


The conserved switch 1 loop of P-loop NTPases is implicated as a central element that transmits information between the nucleotide-binding pocket and the binding site of the partner proteins. Recent structural studies have identified two states of switch 1 in G-proteins and myosin, but their role in the transduction mechanism has yet to be clarified. Single tryptophan residues were introduced into the switch 1 region of myosin II motor domain and studied by rapid reaction methods. We found that in the presence of MgADP, two states of switch 1 exist in dynamic equilibrium. Actin binding shifts the equilibrium towards one of the MgADP states, whereas ATP strongly favors the other. In the light of electron cryo-microscopic and X-ray crystallographic results, these findings lead to a specific structural model in which the equilibrium constant between the two states of switch 1 is coupled to the strength of the actin-myosin interaction. This has implications for the enzymatic mechanism of G-proteins and possibly P-loop NTPases in general.

Original languageEnglish
Pages (from-to)265-274
Number of pages10
JournalEMBO Journal
Issue number1
Publication statusPublished - Jan 10 2007



  • Actomyosin interaction
  • G-proteins
  • Mg-binding
  • Nucleotide binding
  • Tryptophan fluorescence

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

Cite this

Kintses, B., Gyimesi, M., Pearson, D. S., Geeves, M. A., Zeng, W., Bagshaw, C. R., & Málnási-Csizmadia, A. (2007). Reversible movement of switch 1 loop of myosin determines actin interaction. EMBO Journal, 26(1), 265-274.