Elastic filaments in skeletal muscle revealed by selective removal of thin filaments with plasma gelsolin

Takashi Funatsu, Hideo Higuchi, Shin'ichi Ishiwata

    Research output: Contribution to journalArticle

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    Abstract

    Muscle needs an elastic framework to maintain its mechanical stability. Removal of thin filaments in rabbit skeletal muscle with plasma gelsolin has revealed the essential features of elastic filaments. The selective removal of thin filaments was confirmed by staining with phalloidin-rhodamine for fluorescence microscopy, examination of arrowhead formation with myosin subfragment 1 by electron microscopy, and analysis by SDS-PAGE. Thin section electron microscopy revealed the elastic fine filaments (∼4 nm in diameter) connecting thick filaments and the Z line. After removal of thin filaments, both rigor stiffness and active tension generation were lost, but the resting tension remained. These observations indicate that the thin filament-free fibers maintain a framework composed of the serial connections of thick filaments, the elastic filaments, and the Z line, which gives passive elasticity to the contractile system of skeletal muscle. The resting tension that remained in the thin filament-free fibers was decreased by mild trypsin treatment. The only protein component that was digested in parallel with the decrease in the resting tension and the disappearance of the elastic filaments was α-connectin (also called titin 1), which was transformed from the α to the β form (from titin 1 to 2, respectively). Thus, we conclude that the main protein component of the elastic filaments is α-connectin (titin 1).

    Original languageEnglish
    Pages (from-to)53-62
    Number of pages10
    JournalJournal of Cell Biology
    Volume110
    Issue number1
    Publication statusPublished - 1990 Jan

    ASJC Scopus subject areas

    • Cell Biology

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