Myosin-Va Regulates Exocytosis through the Submicromolar Ca<sup>2</sup>+-dependent Binding of Syntaxin-1A

  • Michitoshi Watanabe
    Division of Molecular and Cellular Biology, Niigata University, Niigata, Niigata 951-8510, Japan
  • Kazushige Nomura
    Division of Molecular and Cellular Biology, Niigata University, Niigata, Niigata 951-8510, Japan
  • Akihiro Ohyama
    Department of Molecular and Cellular Neurobiology, Gunma University School of Medicine, Maebashi, Gunma 371-8511, Japan
  • Ryoki Ishikawa
    Department of Molecular and Cellular Pharmacology, Gunma University School of Medicine, Maebashi, Gunma 371-8511, Japan
  • Yoshiaki Komiya
    Department of Molecular and Cellular Neurobiology, Gunma University School of Medicine, Maebashi, Gunma 371-8511, Japan
  • Kohei Hosaka
    Basic Sciences for Medicine, Gunma University School of Health Sciences, Maebashi, Gunma 371-8514, Japan
  • Emiko Yamauchi
    Division of Enzyme Physiology, Institute for Enzyme Research, University of Tokushima, Tokushima, Tokushima 770-8503, Japan
  • Hisaaki Taniguchi
    Division of Enzyme Physiology, Institute for Enzyme Research, University of Tokushima, Tokushima, Tokushima 770-8503, Japan
  • Nobuyuki Sasakawa
    Life Science Institute, Sophia University, Chiyoda-ku, Tokyo 102-8554, Japan
  • Konosuke Kumakura
    Life Science Institute, Sophia University, Chiyoda-ku, Tokyo 102-8554, Japan
  • Tatsuo Ushiki
    Division of Microscopic Anatomy and Bio-Imaging, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Niigata 951-8510, Japan
  • Osamu Sato
    Department of Physiology, University of Massachusetts Medical School, Worcester, MA 01655-0127
  • Mitsuo Ikebe
    Department of Physiology, University of Massachusetts Medical School, Worcester, MA 01655-0127
  • Michihiro Igarashi
    Division of Molecular and Cellular Biology, Niigata University, Niigata, Niigata 951-8510, Japan

抄録

<jats:p>Myosin-Va is an actin-based processive motor that conveys intracellular cargoes. Synaptic vesicles are one of the most important cargoes for myosin-Va, but the role of mammalian myosin-Va in secretion is less clear than for its yeast homologue, Myo2p. In the current studies, we show that myosin-Va on synaptic vesicles interacts with syntaxin-1A, a t-SNARE involved in exocytosis, at or above 0.3 μM Ca<jats:sup>2+</jats:sup>. Interference with formation of the syntaxin-1A–myosin–Va complex reduces the exocytotic frequency in chromaffin cells. Surprisingly, the syntaxin-1A-binding site was not in the tail of myosin-Va but rather in the neck, a region that contains calmodulin-binding IQ-motifs. Furthermore, we found that syntaxin-1A binding by myosin-Va in the presence of Ca<jats:sup>2+</jats:sup>depends on the release of calmodulin from the myosin-Va neck, allowing syntaxin-1A to occupy the vacant IQ-motif. Using an anti-myosin-Va neck antibody, which blocks this binding, we demonstrated that the step most important for the antibody's inhibitory activity is the late sustained phase, which is involved in supplying readily releasable vesicles. Our results demonstrate that the interaction between myosin-Va and syntaxin-1A is involved in exocytosis and suggest that the myosin-Va neck contributes not only to the large step size but also to the regulation of exocytosis by Ca<jats:sup>2+</jats:sup>.</jats:p>

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詳細情報

  • CRID
    1364233271200564352
  • NII論文ID
    30018380157
  • DOI
    10.1091/mbc.e05-03-0252
  • ISSN
    19394586
    10591524
  • データソース種別
    • Crossref
    • CiNii Articles

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