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Tomographic 3D Reconstruction of Quick-Frozen, Ca2+-Activated Contracting Insect Flight Muscle
Motor actions of myosin were directly visualized by electron tomography of insect flight muscle quick-frozen during contraction, suggesting the MD tilts and slews on actin from weak to strong binding, followed by swinging of the LCD through an approximately 35 degrees axial angle. Expand
Structure of myosin filaments from relaxed Lethocerus flight muscle by cryo-EM at 6 Å resolution
A cryo–electron microscopy three-dimensional image reconstruction of relaxed myosin II–containing thick filaments from the flight muscle of the giant water bug Lethocerus indicus is described, revealing unique molecular motor conformation and unprecedented details of the filament backbone. Expand
X-ray diffraction evidence for myosin-troponin connections and tropomyosin movement during stretch activation of insect flight muscle
The time-resolved sequence of molecular changes suggests a mechanism for stretch activation, in which troponin bridges mechanically tug tropomyosin aside to relieve tropomyOSin’s steric blocking of myosin–actin binding, which enables subsequent force production. Expand
Ca-activation and stretch-activation in insect flight muscle.
It is suggested that stretch-induced distortion of attached cross-bridges relieves the steric blocking by tropomyosin of additional binding sites on actin, thereby enabling maximum force even at low [Ca(2+]], and trigger a common process of cross-bridge attachment and force production. Expand
Rigor crossbridge structure in tilted single filament layers and flared-X formations from insect flight muscle.
  • M. Reedy, M. Reedy
  • Materials Science, Medicine
  • Journal of molecular biology
  • 5 September 1985
Improved fixation with tannic acid/glutaraldehyde allows us to distinguish three crossbridge domains in flared-X arms: a dense bulb-like head merged into the thin filament; a dense but thinner neck tangential to actin; and a faint thin stem joining the necks to myosin filaments. Expand
X-ray diffraction indicates that active cross-bridges bind to actin target zones in insect flight muscle.
It is concluded that stretch-activated tension of IFM is produced by cross-bridges that bind to rigor's lead-bridge target zones, comprising < or = 1/3 of the 75-80% that attach in rigor. Expand
Electron tomography of fast frozen, stretched rigor fibers reveals elastic distortions in the myosin crossbridges.
"Map back" images that replaced each unaveraged 39 nm crossbridge motif by its class average showed an ordered mix of distorted and unaltered crossbridges distributed along the 116 nm repeat that reflects differences in rigor myosin head loading even before stretch. Expand
Cross-Bridges and Periods in Insect Flight Muscle
The periodic structure of the cross-bridge lattice of glycerinated Lethocerus flight muscle has been studied in sections by electron microscopy, assisted by optical diffraction, and in unfixed fiber bundles by X-ray diffraction to lend credence to the theory that all bridges may swing synchronously during typical, low-amplitude, oscillatory contractions. Expand