Myosin-Va Regulates Exocytosis through the Submicromolar Ca2+-dependent Binding of Syntaxin-1A
| Autor: | Osamu Sato, Mitsuo Ikebe, Yoshiaki Komiya, Michitoshi Watanabe, Tatsuo Ushiki, Ryoki Ishikawa, Kazushige Nomura, Kohei Hosaka, Hisaaki Taniguchi, Konosuke Kumakura, Emiko Yamauchi, Michihiro Igarashi, Nobuyuki Sasakawa, Akihiro Ohyama |
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| Rok vydání: | 2005 |
| Předmět: |
Chromaffin Cells
Molecular Sequence Data Myosin Type V Syntaxin 1 macromolecular substances Plasma protein binding Biology Microscopy Atomic Force environment and public health Synaptic vesicle Exocytosis Myosin Animals Amino Acid Sequence Molecular Biology Cells Cultured Actin Myosin Heavy Chains Brain Munc-18 Articles Cell Biology Rats Cell biology Calcium Synaptic Vesicles Intracellular Protein Binding |
| Zdroj: | Molecular Biology of the Cell. 16:4519-4530 |
| ISSN: | 1939-4586 1059-1524 |
| DOI: | 10.1091/mbc.e05-03-0252 |
| Popis: | 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 Ca2+. 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 Ca2+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 Ca2+. |
| Databáze: | OpenAIRE |
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