ATP-Mg/Pi carrier activity in rat liver mitochondria.
ATP-Mg/Pi carrier activity in rat liver mitochondria.
复制标题
大鼠肝线粒体中的 ATP-Mg/Pi 载体活性。
DOI：
10.1016/0003-9861(92)90628-a
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发表时间：
1992
影响因子：
3.9
通讯作者：
Aprille,JR
中科院分区：
文献类型：
--
作者：
Nosek,MT;Aprille,JR
肝线粒体ATP Mg Pi载体被微摩尔Ca 2+激活，介导腺嘌呤核苷酸净转运进出线粒体基质。本研究的目的是表征某些特征的ATP-Mg P i载体活性是必不可少的了解线粒体腺嘌呤核苷酸含量是如何调节。ATP和ADP作为转运底物的相对重要性进行了研究，使用特定的陷阱测定，以测量其载体介导的外排与PI作为外部counterparts的单独速率。在通电条件下，ATP外排占总ATP+ ADP外排的88%。与寡霉素存在降低基质ATP/ADP比率，ATP流出被消除和ADP流出相对不受影响。Mg 2+是ATP内流所必需的化学计量，可能与ATP同时转运. Ca 2+和Mn 2+可以替代化学计量的Mg 2+。ADP内流和PI诱导的腺嘌呤核苷酸外流不受Mg 2+的影响。用P i类似物进行的实验表明，P i是以二价阴离子HPO 4 2−的形式转运的。结果表明，ATP Mg和二价Pi是主要的转运底物，ATP Mg Pi载体的转运机制可能是电中性交换.结果与以下假设一致：腺嘌呤核苷酸净移动的方向和幅度主要由线粒体内膜上的（ATP-Mg）2-和HPO 4 2-浓度梯度决定。
Abstract The ATP-Mg P i carrier in liver mitochondria is activated by micromolar Ca 2+ and mediates net adenine nucleotide transport into and out of the mitochondrial matrix. The purpose of this study was to characterize certain features of ATP-Mg P i carrier activity that are essential for understanding how the mitochondrial adenine nucleotide content is regulated. The relative importance of ATP and ADP as transport substrates was investigated using specific trap assays to measure their separate rates of carrier-mediated efflux with P i as the external counterion. Under energized conditions ATP efflux accounted for 88% of total ATP+ ADP efflux. With oligomycin present to lower the matrix ATP ADP ratio, ATP efflux was eliminated and ADP efflux was relatively unaffected. Mg 2+ was stoichiometrically required for ATP influx and is probably transported simultaneously with ATP. Ca 2+ and Mn 2+ could substitute for the stoichiometric Mg 2+ requirement. ADP influx and P i-induced adenine nucleotide efflux were unaffected by external Mg 2+. Experiments with P i analogues suggested that P i is transported as the divalent anion, HPO 4 2−. The results show that ATP-Mg and divalent P i are the major transport substrates; the most probable transport mechanism for the ATP-Mg P i carrier is an electroneutral exchange. The results are consistent with the hypothesis that the direction and magnitude of net adenine nucleotide movements are determined mainly by the (ATP-Mg) 2− and HPO 4 2− concentration gradients across the inner mitochondrial membrane.