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Vesicle fusion is the merging of a vesicle with other vesicles or a part of a cell membrane. In the latter case, it is the end stage of secretion from secretory vesicles, where their contents are expelled from the cell through exocytosis. Vesicles can also fuse with other target cell compartments, such as a lysosome. Vesicle fusion may depend on SNARE proteins in the presence of increased intracellular calcium (Ca2+) concentration. ==Triggers== Stimuli that trigger vesicle fusion act by increasing intracellular Ca2+. * Synaptic vesicles commit vesicle fusion by a nerve impulse reaching the synapse, activating voltage-dependent calcium channels that cause influx of Ca2+ into the cell. * In the endocrine system, many hormones are released by their releasing hormones binding to G protein coupled receptors coupled to the Gq alpha subunit, activating the IP3/DAG pathway to increase Ca2+. Examples of this mechanism include: * *Gonadotropin releasing hormone 〔Page 237 in: 〕 * *Thyrotropin releasing hormone〔 * *Growth hormone releasing hormone〔 (minor pathway - main one is cAMP dependent pathway ) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「vesicle fusion」の詳細全文を読む スポンサード リンク
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