Nakamura T, Tokuda H, Unemoto T
Biochim Biophys Acta. 1984 Oct 3;776(2):330-6. doi: 10.1016/0005-2736(84)90222-0.
The marine bacterium, Vibrio alginolyticus, regulates the cytoplasmic pH at about 7.8 over the pH range 6.0-9.0. By the addition of diethanolamine (a membrane-permeable amine) at pH 9.0, the internal pH was alkalized and simultaneously the cellular K+ was released. Following the K+ exit, the internal pH was acidified until 7.8, where the K+ exit leveled off. The K+ exit was mediated by a K+/H+ antiporter that is driven by the outwardly directed K+ gradient and ceases to function at the internal pH of 7.8 and below. The Na+-loaded cells assayed in the absence of KCl generated inside acidic delta pH at alkaline pH due to the function of an Na+/H+ antiporter, but the internal pH was not maintained at a constant value. At acidic pH range, the addition of KCl to the external medium was necessary for the alkalization of cell interior. These results suggested that in cooperation with the K+ uptake system and H+ pumps, the K+/H+ antiporter functions as a regulator of cytoplasmic pH to maintain a constant value of 7.8 over the pH range 6.0-9.0.
海洋细菌溶藻弧菌在pH值6.0至9.0的范围内将细胞质pH调节至约7.8。在pH值为9.0时添加二乙醇胺（一种可透过膜的胺），内部pH值碱化，同时细胞内的钾离子被释放。钾离子流出后，内部pH值酸化直至7.8，此时钾离子流出趋于平稳。钾离子流出由钾离子/氢离子反向转运体介导，该转运体由外向的钾离子梯度驱动，在内部pH值为7.8及以下时停止运作。在无氯化钾的情况下检测的钠离子负载细胞，由于钠离子/氢离子反向转运体的作用，在碱性pH值下会产生内部酸性ΔpH，但内部pH值并未维持在恒定值。在酸性pH范围内，向外部培养基中添加氯化钾对于细胞内部的碱化是必要的。这些结果表明，钾离子/氢离子反向转运体与钾离子摄取系统和氢离子泵协同作用，作为细胞质pH的调节剂，在pH值6.0至9.0的范围内维持恒定值7.8。
