Departament de Bioquímica i Biologia Molecular, Ed. V, Universitat Autònoma de Barcelona, Bellaterra 08193, Barcelona, Spain.
Microbiol Mol Biol Rev. 2010 Mar;74(1):95-120. doi: 10.1128/MMBR.00042-09.
The maintenance of appropriate intracellular concentrations of alkali metal cations, principally K(+) and Na(+), is of utmost importance for living cells, since they determine cell volume, intracellular pH, and potential across the plasma membrane, among other important cellular parameters. Yeasts have developed a number of strategies to adapt to large variations in the concentrations of these cations in the environment, basically by controlling transport processes. Plasma membrane high-affinity K(+) transporters allow intracellular accumulation of this cation even when it is scarce in the environment. Exposure to high concentrations of Na(+) can be tolerated due to the existence of an Na(+), K(+)-ATPase and an Na(+), K(+)/H(+)-antiporter, which contribute to the potassium balance as well. Cations can also be sequestered through various antiporters into intracellular organelles, such as the vacuole. Although some uncertainties still persist, the nature of the major structural components responsible for alkali metal cation fluxes across yeast membranes has been defined within the last 20 years. In contrast, the regulatory components and their interactions are, in many cases, still unclear. Conserved signaling pathways (e.g., calcineurin and HOG) are known to participate in the regulation of influx and efflux processes at the plasma membrane level, even though the molecular details are obscure. Similarly, very little is known about the regulation of organellar transport and homeostasis of alkali metal cations. The aim of this review is to provide a comprehensive and up-to-date vision of the mechanisms responsible for alkali metal cation transport and their regulation in the model yeast Saccharomyces cerevisiae and to establish, when possible, comparisons with other yeasts and higher plants.
维持适当的细胞内碱金属阳离子浓度，主要是 K(+) 和 Na(+)，对活细胞至关重要，因为它们决定细胞体积、细胞内 pH 值和质膜两侧的电势，以及其他重要的细胞参数。酵母已经发展出许多策略来适应环境中这些阳离子浓度的巨大变化，基本上是通过控制运输过程。质膜高亲和力 K(+)转运体允许细胞内积累这种阳离子，即使环境中缺乏 K(+)。由于存在 Na(+)，K(+)-ATP 酶和 Na(+)，K(+)/H(+)-反向转运体，酵母可以耐受高浓度的 Na(+)，它们有助于钾的平衡。阳离子也可以通过各种反向转运体被隔离到细胞内的细胞器中，如液泡。尽管仍然存在一些不确定性，但在过去的 20 年中，已经确定了负责酵母膜中碱金属阳离子通量的主要结构成分的性质。相比之下，在许多情况下，调节成分及其相互作用仍然不清楚。保守的信号通路（如钙调神经磷酸酶和 HOG）已知参与调节质膜水平的流入和流出过程，尽管分子细节尚不清楚。同样，对于细胞器运输和碱金属阳离子的稳态的调节知之甚少。本综述的目的是提供一个关于负责碱金属阳离子运输的机制的全面和最新的视角，并在可能的情况下与其他酵母和高等植物进行比较。
