title: Mechanical measurements of single actomyosin motor force.
abstract: To elucidate the mechanism of force generation by actomyosin motor, a measuring system was constructed, in which an in vitro motility assay was combined with an optical trapping technique. An actin filament of several micron long was attached to a gelsolin-coated polystyrene bead, and was allowed to interact with a small number (approximately 1/1 micron actin filament) of rabbit skeletal heavy meromyosin (an active subfragment of myosin) molecules bound to a nitrocellulose-coated coverglass. The bead position was determined at 33-ms intervals. We measured the force generation event at relatively low (100-400 nM) ATP concentration so that the occurrence of individual force generation events could be detected with our time resolution. The actin-bound bead held in the optical trap moved in a stepwise manner in the direction of the actin filament only in the presence of ATP. At the trap strength of 0.3 pN/nm, the maximum size of the step was 11 nm, and the maximum force associated with the movement was 3.3 pN.
authors.affiliation: Department of Physics, Faculty of Science and Technology, Keio University, Yokohama, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Miyata
authors.forename: H
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: H
authors.initials: H
authors.lastname: Hakozaki
authors.forename: N
authors.initials: N
authors.lastname: Suzuki
authors.forename: T
authors.initials: T
authors.lastname: Furuno
authors.forename: A
authors.initials: A
authors.lastname: Ikegami
authors.forename: K
authors.initials: K
authors.lastname: Kinosita
authors.forename: T
authors.initials: T
authors.lastname: Nishizaka
authors.forename: S
authors.initials: S
authors.lastname: Ishiwata
mesh_terms: D000199:Actins / Q000502:physiology; D000205:Actomyosin / Q000502:physiology*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001696:Biomechanical Phenomena; D055592:Biophysical Phenomena; D001703:Biophysics; D066298:In Vitro Techniques; D008854:Microscopy, Electron; D009068:Movement / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D015879:Myosin Subfragments / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D011487:Protein Conformation; D011817:Rabbits
chemical_list: D000199:Actins; D015879:Myosin Subfragments; D000255:Adenosine Triphosphate; D000205:Actomyosin