A new muscle contractile system composed of a thick filament lattice and a single actin filament

Madoka Suzuki, Hideaki Fujita, Shin'ichi Ishiwata

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

To bridge the gap between the contractile system in muscle and in vitro motility assay, we have devised an A-band motility assay system. A glycerinated skeletal myofibril was treated with gelsolin to selectively remove the thin filaments and expose a single A-band. A single bead-tailed actin filament trapped by optical tweezers was made to interact with the inside or the outer surface of the A-band, and the displacement of the bead-tailed filament was measured in a physiological ionic condition by phase-contrast and fluorescence microscopy. We observed large back-and-forth displacement of the filament accompanied by a large change in developed force. Despite this large tension fluctuation, we found that the average force was proportional to the overlap inside and outside the A-band up to ∼150 nm and 300 nm from the end of the A-band, respectively. Consistent with the difference in the density of myosin molecules, the average force per unit length of the overlap inside the A-band (the time-averaged force/myosin head was ∼1 pN) was approximately twice as large as that outside. Thus, we conclude that the A-band motility assay system described here is suitable for studying force generation on a single actin filament, and its sliding movement within a regular three-dimensional thick filament lattice.

Original languageEnglish
Pages (from-to)321-328
Number of pages8
JournalBiophysical Journal
Volume89
Issue number1
DOIs
Publication statusPublished - 2005 Jul

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Myosins
Actin Cytoskeleton
Optical Tweezers
Gelsolin
Phase-Contrast Microscopy
Muscles
Myofibrils
Fluorescence Microscopy
In Vitro Techniques

ASJC Scopus subject areas

  • Biophysics

Cite this

A new muscle contractile system composed of a thick filament lattice and a single actin filament. / Suzuki, Madoka; Fujita, Hideaki; Ishiwata, Shin'ichi.

In: Biophysical Journal, Vol. 89, No. 1, 07.2005, p. 321-328.

Research output: Contribution to journalArticle

Suzuki, Madoka ; Fujita, Hideaki ; Ishiwata, Shin'ichi. / A new muscle contractile system composed of a thick filament lattice and a single actin filament. In: Biophysical Journal. 2005 ; Vol. 89, No. 1. pp. 321-328.
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