Nicholls David G
Buck Institute for Age Research, Redwood Boulevard, Novato, CA 94945, USA.
Cell Calcium. 2005 Sep-Oct;38(3-4):311-7. doi: 10.1016/j.ceca.2005.06.011.
The kinetic properties for the uptake, storage and release of Ca2+ from isolated mitochondria accurately predict the behaviour of the organelles within the intact cell. While the steady-state cycling of Ca2+ across the inner membrane between independent uptake and efflux pathways seems at first sight to be symmetrical, the distinctive kinetics of the uniporter, which is highly dependent on external free Ca2+ concentration and the efflux pathway, whose activity is clamped over a wide range of total matrix Ca2+ by the solubility of the calcium phosphate complex provide a mechanism whereby mitochondria reversibly sequester transient elevations in cytoplasmic Ca2+. Under non-stimulated conditions, the same transport processes can regulate matrix Ca2+ concentrations and hence citric acid cycle activity.
从分离的线粒体摄取、储存和释放Ca2+的动力学特性准确地预测了完整细胞内细胞器的行为。虽然Ca2+在内膜上独立摄取和流出途径之间的稳态循环乍一看似乎是对称的，但单向转运体独特的动力学高度依赖于外部游离Ca2+浓度，而流出途径的活性在广泛的总基质Ca2+范围内因磷酸钙复合物的溶解度而受到钳制，这提供了一种机制，通过该机制线粒体可逆地隔离细胞质Ca2+的瞬时升高。在非刺激条件下，相同的转运过程可以调节基质Ca2+浓度，从而调节柠檬酸循环活性。
