Serrano R
Eur J Biochem. 1977 Oct 17;80(1):97-102. doi: 10.1111/j.1432-1033.1977.tb11861.x.
Maltose transport in yeast (Saccharomyces cerevisiae) is inhibited by uncouplers under conditions where the intracellular concentration of the sugar is lower than in the medium. The uncouplers did not deplete the ATP content of the yeast cells and a 50--100-fold reduction in ATP caused by antimycin and 2-deoxyglucose had no effect on maltose transport. In ATP-depleted cells, the maltose transported is partially hydrolyzed to glucose but not further metabolized and therefore a mechanism of transport involving phosphorylation can be discarded. One proton is cotransported with every maltose molecule. The fact that maltose transport is inhibited by KCl but not by NaCl, Tris-Cl or KSCN suggest that the electroneutrality during maltose and proton uptake can be maintained by the exit of K+ from the cells or by the entry of a permeable anion as SCN-. These results indicate that the translocation of maltose across the yeast plasma membrane is not dependent on ATP and is coupled to the electrochemical gradient of protons in this membrane. When this gradient is abolished by uncouplers, the transport system is not able to function even in favour of a concentration gradient of the sugar.
在酵母（酿酒酵母）中，当细胞内糖浓度低于培养基中的糖浓度时，麦芽糖转运受到解偶联剂的抑制。解偶联剂不会耗尽酵母细胞的ATP含量，由抗霉素和2 - 脱氧葡萄糖引起的ATP含量降低50 - 100倍对麦芽糖转运没有影响。在ATP耗尽的细胞中，转运的麦芽糖部分水解为葡萄糖，但不会进一步代谢，因此可以排除涉及磷酸化的转运机制。每一个麦芽糖分子伴随着一个质子共转运。麦芽糖转运受KCl抑制，但不受NaCl、Tris - Cl或KSCN抑制，这一事实表明，麦芽糖和质子摄取过程中的电中性可以通过K⁺从细胞中流出或通过可渗透阴离子如SCN⁻进入来维持。这些结果表明，麦芽糖跨酵母质膜的转运不依赖于ATP，而是与该膜中质子的电化学梯度偶联。当这种梯度被解偶联剂消除时，即使有利于糖的浓度梯度，转运系统也无法发挥作用。
