Calcium uptake in isolated hepatic plasma-membrane vesicles.
Calcium uptake in isolated hepatic plasma-membrane vesicles.
复制标题
离体肝质膜囊泡的钙摄取。
DOI：
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发表时间：
1982
期刊：
影响因子：
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通讯作者：
E. Carafoli
中科院分区：
文献类型：
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作者：
N. Kraus;J. Biber;H. Murer;E. Carafoli
分离出能够摄取Ca 2+的肝质膜组分。该馏分表现出高Na+，K+-ATP酶，低葡萄糖-6磷酸酶活性，并在Na+依赖的方式运输丙氨酸。Ca 2+的摄取是ATP依赖性的; UTP、GTP或CTP不能替代ATP。草酸盐的存在并没有显着改变摄取率。反应的最适pH是碱性的（在pH 6.8下没有可见的吸收）。这些特性与内质网Ca 2+摄取系统的特性不同，内质网Ca 2+摄取系统依赖于磷酸盐，并且具有酸性pH最佳值。ATP依赖性Ca 2+摄取的Km（Ca 2+）为1.4 × 10（-8）M，转运的Vmax为30 nmol × mg蛋白-1 × min-1。没有得到结论性的结果，钙调素敏感性的过程：除了钙调素的囊泡没有刺激摄取，抗钙调素药物三氟拉嗪没有抑制作用。然而，另一种抗钙调素药物（R24571）具有有限的，但具有统计学意义的抑制作用。通过加入Na+可以诱导囊泡中积累的Ca 2+的部分释放，并且在高Na+培养基中孵育囊泡（与高K+培养基相比）导致较低（约25%）的钙摄取。积累的Ca ~（2+）的部分释放也可以通过加入H ~+来诱导。H+的释放效果，结合在酸性pH下不存在Ca 2+吸收，表明H+/Ca 2+交换的可能性。
A liver plasma-membrane fraction capable of Ca2+ uptake was isolated. The fraction exhibited high Na+, K+-ATPase, low glucose-6 phosphatase activity, and transported alanine in a Na+-dependent fashion. The uptake of Ca2+ was ATP-dependent; UTP, GTP, or CTP did not substitute for ATP. The presence of oxalate did not significantly alter the rate of uptake. The pH optimum of the reaction was basic (no uptake was visible at pH 6.8). These properties are at variance with those of the endoplasmic reticulum Ca2+ uptake system, which is oxalate-dependent, and has an acid pH optimum. The ATP-dependent Ca2+ uptake has a Km(Ca2+) of 1.4 X 10(-8) M and a Vmax of transport of 30 nmol X mg protein-1 X min-1. No conclusive results were obtained on the calmodulin-sensitivity of the process: addition of calmodulin to the vesicles did not stimulate uptake, and the anti-calmodulin drug trifluoperazine had no inhibitory effect. However, another anti-calmodulin drug (R24571) had a limited, but statistically significant, inhibitory action. A partial release of the accumulated Ca2+ from the vesicles could be induced by the addition of Na+, and incubation of the vesicles in a high Na+ medium (as compared to high K+ medium) resulted in lower (about 25%) calcium uptake. Partial release of the accumulated Ca2+ could be induced also by the addition of H+. The releasing effect of H+, taken together with the absence of Ca2+ uptake at acid pH, suggests the possibility of a H+/Ca2+ exchange.
肝线粒体和内质网对游离 Ca2 的调节。
DOI：
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发表时间：
1980
期刊：
The Journal of biological chemistry
影响因子：
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作者：
Becker,GL;Fiskum,G;Lehninger,AL
通讯作者：
Lehninger,AL