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The Calcium Sensitivity of Individual Secretory Vesicles Is Invariant with the Rate of Calcium Delivery
Differences in the calcium sensitivity of individual secretory vesicles can explain a defining feature of calcium-regulated exocytosis, a graded response to calcium. The role of the time dependence of calcium delivery in defining the observed differences in the calcium sensitivity of sea urchin egg...
Autores principales: | , , , , , , |
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Formato: | Texto |
Lenguaje: | English |
Publicado: |
The Rockefeller University Press
1998
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2229436/ https://www.ncbi.nlm.nih.gov/pubmed/9806966 |
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author | Blank, Paul S. Vogel, Steven S. Cho, Myoung-Soon Kaplan, Doron Bhuva, Devang Malley, James Zimmerberg, Joshua |
author_facet | Blank, Paul S. Vogel, Steven S. Cho, Myoung-Soon Kaplan, Doron Bhuva, Devang Malley, James Zimmerberg, Joshua |
author_sort | Blank, Paul S. |
collection | PubMed |
description | Differences in the calcium sensitivity of individual secretory vesicles can explain a defining feature of calcium-regulated exocytosis, a graded response to calcium. The role of the time dependence of calcium delivery in defining the observed differences in the calcium sensitivity of sea urchin egg secretory vesicles in vitro was examined. The calcium sensitivity of individual secretory vesicles (i.e., the distribution of calcium thresholds) is invariant over a range of calcium delivery rates from faster than micromolar per millisecond to slower than micromolar per second. Any specific calcium concentration above threshold triggers subpopulations of vesicles to fuse, and the size of these subpopulations is independent of the time course required to reach that calcium concentration. All evidence supports the hypothesis that the magnitude of the free calcium is the single controlling variable that determines the fraction of vesicles that fuse, and that this fraction is established before the application of calcium. Submaximal responses to calcium cannot be attributed to alterations in the calcium sensitivity of individual secretory vesicles arising from the temporal properties of the calcium delivery. Models that attempt to explain the cessation of fusion using changes in the distribution of calcium thresholds arising from the rate of calcium delivery and/or adaptation are not applicable to this system, and thus cannot be general. |
format | Text |
id | pubmed-2229436 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1998 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-22294362008-04-21 The Calcium Sensitivity of Individual Secretory Vesicles Is Invariant with the Rate of Calcium Delivery Blank, Paul S. Vogel, Steven S. Cho, Myoung-Soon Kaplan, Doron Bhuva, Devang Malley, James Zimmerberg, Joshua J Gen Physiol Article Differences in the calcium sensitivity of individual secretory vesicles can explain a defining feature of calcium-regulated exocytosis, a graded response to calcium. The role of the time dependence of calcium delivery in defining the observed differences in the calcium sensitivity of sea urchin egg secretory vesicles in vitro was examined. The calcium sensitivity of individual secretory vesicles (i.e., the distribution of calcium thresholds) is invariant over a range of calcium delivery rates from faster than micromolar per millisecond to slower than micromolar per second. Any specific calcium concentration above threshold triggers subpopulations of vesicles to fuse, and the size of these subpopulations is independent of the time course required to reach that calcium concentration. All evidence supports the hypothesis that the magnitude of the free calcium is the single controlling variable that determines the fraction of vesicles that fuse, and that this fraction is established before the application of calcium. Submaximal responses to calcium cannot be attributed to alterations in the calcium sensitivity of individual secretory vesicles arising from the temporal properties of the calcium delivery. Models that attempt to explain the cessation of fusion using changes in the distribution of calcium thresholds arising from the rate of calcium delivery and/or adaptation are not applicable to this system, and thus cannot be general. The Rockefeller University Press 1998-11-01 /pmc/articles/PMC2229436/ /pubmed/9806966 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/). |
spellingShingle | Article Blank, Paul S. Vogel, Steven S. Cho, Myoung-Soon Kaplan, Doron Bhuva, Devang Malley, James Zimmerberg, Joshua The Calcium Sensitivity of Individual Secretory Vesicles Is Invariant with the Rate of Calcium Delivery |
title | The Calcium Sensitivity of Individual Secretory Vesicles Is Invariant with the Rate of Calcium Delivery |
title_full | The Calcium Sensitivity of Individual Secretory Vesicles Is Invariant with the Rate of Calcium Delivery |
title_fullStr | The Calcium Sensitivity of Individual Secretory Vesicles Is Invariant with the Rate of Calcium Delivery |
title_full_unstemmed | The Calcium Sensitivity of Individual Secretory Vesicles Is Invariant with the Rate of Calcium Delivery |
title_short | The Calcium Sensitivity of Individual Secretory Vesicles Is Invariant with the Rate of Calcium Delivery |
title_sort | calcium sensitivity of individual secretory vesicles is invariant with the rate of calcium delivery |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2229436/ https://www.ncbi.nlm.nih.gov/pubmed/9806966 |
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