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The motor protein myosin-i produces its working stroke in two steps

Academic Article
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Overview

related to degree

  • Jontes, James David, Ph.D. in Biology, Scripps Research 1992 - 1997

authors

  • Veigel, C.
  • Coluccio, L. M.
  • Jontes, James David
  • Sparrow, J. C.
  • Milligan, Ronald
  • Molloy, J. E.

publication date

  • 1999

journal

  • Nature  Journal

abstract

  • Many types of cellular motility, including muscle contraction, are driven by the cyclical interaction of the motor protein myosin with actin filaments, coupled to the breakdown of ATP. It is thought that myosin binds to actin and then produces force and movement as it 'tilts' or 'rocks' into one or more subsequent, stable conformations. Here we use an optical-tweezers transducer to measure the mechanical transitions made by a single myosin head while it is attached to actin. We find that two members of the myosin-I family, rat liver myosin-I of relative molecular mass 130,000 (M(r) 130K) and chick intestinal brush-border myosin-I, produce movement in two distinct steps. The initial movement (of roughly 6 nanometres) is produced within 10 milliseconds of actomyosin binding, and the second step (of roughly 5.5 nanometres) occurs after a variable time delay. The duration of the period following the second step is also variable and depends on the concentration of ATP. At the highest time resolution possible (about 1 millisecond), we cannot detect this second step when studying the single-headed subfragment-1 of fast skeletal muscle myosin II. The slower kinetics of myosin-I have allowed us to observe the separate mechanical states that contribute to its working stroke.

subject areas

  • Actins
  • Actomyosin
  • Adenosine Triphosphate
  • Animals
  • Biomechanical Phenomena
  • In Vitro Techniques
  • Models, Biological
  • Molecular Motor Proteins
  • Myosin Type I
  • Myosins
  • Protein Binding
  • Rats
  • Transducers
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Identity

International Standard Serial Number (ISSN)

  • 0028-0836

PubMed ID

  • 10206648
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Additional Document Info

start page

  • 530

end page

  • 533

volume

  • 398

issue

  • 6727

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