Rozhmanova O M, Stel'makh L N, Lishko V K
Biokhimiia. 1976 Oct;41(10):1846-9.
A mechanism of K-insensitive, ouabain-dependent liberation of Na+ from the cell during an increase in ADP intracellular concentration is studied. It is shown that the increase in the ADP/ATP ratio does not change the Na+, K+-ATPase affinity to K+ ions and does not result in the Na-activated, K-independent ATPase reaction. ADP protects ATPase from the inhibition by ouabain which is accounted for by a decrease in the concentration of a glycoside-sensitive form of the enzyme E2-P due to a turnover of the phosphokinase step of the reaction, but not due to the binding of free Mg2+ ions. The results obtained suggest that the increase in ADP concentration within the cell activates Na-Nan exchange along Na-transporting channels of the ionic pump.
研究了在细胞内ADP浓度增加期间，钾不敏感、哇巴因依赖的钠离子从细胞中释放的机制。结果表明，ADP/ATP比值的增加不会改变钠钾ATP酶对钾离子的亲和力，也不会导致钠激活、钾不依赖的ATP酶反应。ADP可保护ATP酶免受哇巴因的抑制，这是由于反应中磷酸激酶步骤的周转导致糖苷敏感形式的酶E2-P浓度降低，而不是由于游离镁离子的结合。所得结果表明，细胞内ADP浓度的增加会沿着离子泵的钠转运通道激活钠-钠交换。
