Tomographic 3D reconstruction of quick-frozen, Ca2+-activated contracting insect flight muscle.


Journal Article

Motor actions of myosin were directly visualized by electron tomography of insect flight muscle quick-frozen during contraction. In 3D images, active cross-bridges are usually single myosin heads, bound preferentially to actin target zones sited midway between troponins. Active attached bridges (approximately 30% of all heads) depart markedly in axial and azimuthal angles from Rayment's rigor acto-S1 model, one-third requiring motor domain (MD) tilting on actin, and two-thirds keeping rigor contact with actin while the light chain domain (LCD) tilts axially from approximately 105 degrees to approximately 70 degrees. The results suggest 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, giving an approximately 13 nm interaction distance and an approximately 4-6 nm working stroke.

Full Text

Cited Authors

  • Taylor, KA; Schmitz, H; Reedy, MC; Goldman, YE; Franzini-Armstrong, C; Sasaki, H; Tregear, RT; Poole, K; Lucaveche, C; Edwards, RJ; Chen, LF; Winkler, H; Reedy, MK

Published Date

  • November 12, 1999

Published In

Volume / Issue

  • 99 / 4

Start / End Page

  • 421 - 431

PubMed ID

  • 10571184

Pubmed Central ID

  • 10571184

International Standard Serial Number (ISSN)

  • 0092-8674

Digital Object Identifier (DOI)

  • 10.1016/s0092-8674(00)81528-7


  • eng

Conference Location

  • United States