Structural analysis of muscle thin filament

Akihiro Tomioka, Hans O. Ribi, Makio Tokunaga, Taiji Furuno, Hiroyuki Sasabe, Kenjiro Miyano, Takeyuki Wakabayashi

研究成果: Article査読

5 被引用数 (Scopus)


Thin sheets of Ac-Tm-Tn paracrystals were prepared in the presence of high concentration of Ca2+ ion and three-dimensional image analysis was performed. The optical diffraction pattern of an electron micrograph showed spots up to 1/1.6 nm-1 in the radial direction and up to 1/2.5 nm-1 in the axial direction, the best resolution ever obtained so far. The translationally filtered image showed clear polarity of filament which looked like a "spearhead" per each crossover repeat of actin helix. The three-dimensionally reconstructed model looked very similar to the inner regions (A+B domains) of the Ac-Tm-S1 complex obtained by Toyoshima and Wakabayashi (14, 15) when they were placed so that the "spearhead" pattern of the Tc-Tm-Tn complex and the "arrowhead" pattern of the Ac-Tm-S1 complex pointed in the same direction. The myosin-binding site of actin was identified by comparison of two structures. The model of actin molecule cut out from the thin filament model had a low density region within itself, which was located about 2.5 nm from the helix axis. That low density region divided actin molecule into two domains, a large and a small domain. A dense "pillar" was detected which connected two neighboring actin molecules along a left-handed generic helix 1 nm from the helix axis. Two actin-actin binding sites which were responsible for the connection through the "pillar" were located on the inner surface of actin molecule. To obtain better crystalline arrays of actin, we tried a method utilizing adsorption to lipid. A positively-charged monolayer of lipids was formed on the surface of a small volume of buffer solution which was put in a microwell. Solution of negatively-charged F-actin was then injected into the buffer solution and was allowed to be joined to the lipid monolayer by electrostatic attraction. Fluidity of the lipid monolayer enabled the two-dimensional crystallization of actin. Electron microscopy revealed that larger paracrystalline arrays were formed more rapidly (< 1 hr) than those formed within solution, which demonstrated the advantage of this adsorption method.

ジャーナルAdvances in Biophysics
出版ステータスPublished - 1991

ASJC Scopus subject areas

  • 生物理学
  • 生化学


「Structural analysis of muscle thin filament」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。