Calcium transport driven by a proton motive force in vacuolar membrane vesicles of Saccharomyces cerevisiae.
Calcium transport driven by a proton motive force in vacuolar membrane vesicles of Saccharomyces cerevisiae.
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发表时间：
1983-05
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通讯作者：
Y. Ohsumi;Y. Anraku
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作者：
Y. Ohsumi;Y. Anraku
在ATP存在下，酿酒酵母（Saccharomycescerevisiae）的质膜囊泡积累Ca ~（2+）离子，而在ADP或腺苷酰亚胺二磷酸存在下，膜囊泡不积累Ca ~（2+）。钙转运表现出饱和动力学，Km值为0.1 mM，最佳pH值为6.4。钙离子掺入囊泡是可交换的，并完全释放的质子载体解偶联剂，3，5-二叔丁基-4-羟基benzilidenemalonitrile（SF 6847），或钙特异性离子载体，A23187。这种转运需要Mg ~（2+）离子的参与，但Cu ~（2+）或Zn ~（2+）离子对这种转运有抑制作用，它们是液泡膜H ~+-ATP酶的抑制剂。转运活性对H ~+-ATP酶抑制剂N，N ′-二环己基碳二亚胺敏感，而对寡霉素和钒酸钠不敏感。SF6847或尼日利亚菌素完全阻断Ca ~（2+）的摄取，而缬氨霉素则刺激Ca ~（2+）的摄取1.35倍。这些结果表明质子的电化学电势差是这种Ca 2+运输的驱动力。ATP依赖性的形成的deltapH的囊泡和其部分消散的氯化钙证明通过荧光淬灭的奎纳克林。液泡膜囊泡对Ca ~（2+）的吸收可能是由Ca ~（2+）/H ~+逆向转运系统催化的。
Vacuolar membrane vesicles of Saccharomyces cerevisiae accumulate Ca2+ ion in the presence of ATP, not in the presence of ADP or adenyl-5'-yl imidodiphosphate. Calcium transport showed saturation kinetics with a Km value of 0.1 mM and optimal pH of 6.4. Ca2+ ion incorporated in the vesicles was exchangeable and released completely by a protonophore uncoupler, 3,5-di-tert-butyl-4-hydroxybenzilidenemalononitrile (SF6847), or calcium-specific ionophore, A23187. The transport required Mg2+ ion but was inhibited by Cu2+ or Zn2+ ions, inhibitors of H+-ATPase of the vacuolar membrane. The transport activity was sensitive to the H+-ATPase inhibitor N,N'-dicyclohexylcarbodiimide, but not to oligomycin or sodium vanadate. SF6847 or nigericin blocked Ca2+ uptake completely, but valinomycin stimulated it 1.35-fold. These results indicate that an electrochemical potential difference of protons is a driving force for this Ca2+ transport. The ATP-dependent formation of the deltapH in the vesicles and its partial dissipation by CaCl2 were demonstrated by fluorescence quenching of quinacrine. This Ca2+ uptake by vacuolar membrane vesicles is suggested to be catalyzed by a Ca2+/H+ antiport system.