TRANSPORT IN SACCHAROMYCES CEREVISIAE
TRANSPORT IN SACCHAROMYCES CEREVISIAE
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发表时间：
1994
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通讯作者：
K. Cunningham;G. Fink
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作者：
K. Cunningham;G. Fink
芽殖酵母中胞浆游离Ca 2+通过Ca 2+泵和反向转运蛋白的活性维持在亚微摩尔水平。我们最近已经确定了两个钙泵，PCM1和PMR 1，这是所需的钙螯合到液泡和分泌细胞器，分别结构基因。任一Ca2+泵的功能足以维持酵母的生存能力，但由于胞质[Ca2+]升高和钙调磷酸酶（一种Ca2+和钙调蛋白依赖性蛋白磷酸酶）的激活，两种基因的缺失是致命的。钙调神经磷酸酶的激活通过一个假定的钙逆向转运蛋白降低了液泡中的钙螯合，也可能增加钙泵的活性。这些调节过程可以影响酵母菌株耐受高细胞外[Ca2+]的能力。我们提出了一个模型，在该模型中，细胞对环境中Ca2+水平变化的反应是由钙调蛋白和钙调神经磷酸酶介导的，反过来，调节各种类型的Ca2+转运蛋白。
Cytosolic free Ca2+ is maintained at submicromolar levels in budding yeast by the activity of Ca2+ pumps and antiporters. We have recently identified the structural genes for two Ca2+ pumps, PCM1 and PMR1, which are required for Ca2+ sequestration into the vacuole and secretory organelles, respectively. The function of either Ca2+ pump is sufficient for yeast viability, but deletion of both genes is lethal because of elevation of cytosolic [Ca2+] and activation of calcineurin, a Ca2+and calmodulin-dependent protein phosphatase. Calcineurin activation decreases Ca2+ sequestration in the vacuole by a putative Ca2+ antiporter and may also increase Ca2+ pump activity. These regulatory processes can affect the ability of yeast strains to tolerate high extracellular [Ca2+]. We propose a model in which the cellular response to changes in the environmental levels of Ca2+ is mediated by calmodulin and calcineurin which, in turn, modulate the various types of Ca2+ transporters.