Depletion "skraps" and dynamic buffering inside the cellular calcium store
Depletion "skraps" and dynamic buffering inside the cellular calcium store
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DOI：
10.1073/pnas.0511252103
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发表时间：
2006-02-21
影响因子：
11.1
通讯作者：
Ríos, E
中科院分区：
文献类型：
--
作者：
Launikonis, BS;Zhou, JS;Ríos, E
Ca2+信号由细胞储存的Ca2+释放产生，转换细胞内的代谢反应。在肌肉中，呼叫火花局部表现出细胞范围信号的快速开始和终止。通过使用荧光的移位激发和发射比率对存储内的Call进行成像，进行了令人惊讶的观察：火花或电压诱导的细胞范围释放期间的耗尽发生得太晚，甚至在Ca2+释放通道关闭后仍在继续进行。这一发现表明，调用是从一个''近''区室释放功能之间的存储腔和胞质溶胶。一个邻近的隔间的存在下，也解释了一个矛盾的激增店内Ca2+，这是记录在刺激后，长时间的，全细胞的呼叫释放。一个店内激增后，诱导的Ca2+释放首次报道，在亚细胞存储部分，其来源被追溯到存储缓冲液，calsequestrin。目前的结果更新了不断发展的概念，主要是由于N。Ikemoto和C.作为一个动态存储。考虑到钙螯合蛋白的Ca 2+吸附线性聚合物的战略位置和维度的降低，它们可以比腔存储溶液更有效地将Ca 2+递送到开放的释放通道，从而构成近端隔室。当储存耗尽变得普遍时，聚合物将崩溃以增加储存[Ca2+]并维持驱动释放通量的浓度梯度。
Ca2+ signals, produced by Ca2+ release from cellular stores, switch metabolic responses inside cells. In muscle, Call sparks locally exhibit the rapid start and termination of the cell-wide signal. By imaging Call inside the store using shifted excitation and emission ratioing of fluorescence, a surprising observation was made: Depletion during sparks or voltage-induced cell-wide release occurs too late, continuing to progress even after the Ca2+ release channels have closed. This finding indicates that Call is released from a '' proximate '' compartment functionally in between store lumen and cytosol. The presence of a proximate compartment also explains a paradoxical surge in intrastore Ca2+, which was recorded upon stimulation of prolonged, cell-wide Call release. An intrastore surge upon induction of Ca2+ release was first reported in subcellular store fractions, where its source was traced to the store buffer, calsequestrin. The present results update the evolving concept, largely due to N. Ikemoto and C. Kang, of calsequestrin as a dynamic store. Given the strategic location and reduction of dimensionality of Ca2+-adsorbing linear polymers of calsequestrin, they could deliver Ca2+ to the open release channels more efficiently than the luminal store solution, thus constituting the proximate compartment. When store depletion becomes widespread, the polymers would collapse to increase store [Ca2+] and sustain the concentration gradient that drives release flux.