The immediately releasable pool of secretory vesicles in adrenal chromaffin cells
The exocytosis of hormone-filled vesicles in adrenal chromaffin cells is triggered by localized Ca²⁺ gradients that develops after the activation of voltage-dependent Ca²⁺ channels. To reach the fusion competent state the vesicles go through a variety of maturation steps, including the mobilization...
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| Formato: | Articulo Revision |
| Lenguaje: | Inglés |
| Publicado: |
2018
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| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/127228 https://pmr.safisiol.org.ar/uploadsarchivos/vol_11_n_4_marengo_dw.pdf |
| Aporte de: |
| Sumario: | The exocytosis of hormone-filled vesicles in adrenal chromaffin cells is triggered by localized Ca²⁺ gradients that develops after the activation of voltage-dependent Ca²⁺ channels. To reach the fusion competent state the vesicles go through a variety of maturation steps, including the mobilization through the cytoskeleton, the docking to membrane, and the priming of the exocytotic molecular machinery. However, the fusion readiness of vesicles will also depend on their proximity to the Ca²⁺ source. The immediately releasable pool is a small group of ready–to-fuse vesicles, whose fusion is tightly coupled to Ca²⁺ entry through channels. Recent work indicates that such a coupling is not produced by a random distribution between parts, but is the result of a specific interaction of secretory vesicles with P/Q-type Ca²⁺ channels. The immediately releasable pool is able to sustain with high efficiency the secretion triggered by brief depolarizations applied at low frequencies, like action potentials at basal conditions in adrenal chromaffin cells. |
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