Apell Hans-Jürgen, Diller Anna
University of Konstanz, Biology, Universitätsstrasse 10, Konstanz 78457, Germany.
FEBS Lett. 2002 Dec 4;532(1-2):198-202. doi: 10.1016/s0014-5793(02)03675-x.
In contrast to other P-type ATPases, the Na,K-ATPase binding and release of ions on the cytoplasmic side, to the state called E1, is not electrogenic with the exception of the third Na+. Since the high-resolution structure of the closely related SR Ca-ATPase in state E1 revealed the ion-binding sites deep inside the transmembrane part of the protein, the missing electrogenicity in state E1 can be explained by an obscuring counter-movement of H+ ions. Evidence for such a mechanism is presented by analysis of pH effects on Na+ and K+ binding and by electrogenic H+ movements in the E1 conformation of the Na,K-ATPase.
与其他P型ATP酶不同,钠钾ATP酶在细胞质一侧结合并释放离子形成E1状态时,除了第三个钠离子外,不会产生电效应。由于处于E1状态的密切相关的肌浆网钙ATP酶的高分辨率结构揭示了蛋白质跨膜部分深处的离子结合位点,E1状态中缺失的电效应可以通过氢离子的隐蔽反向移动来解释。通过分析pH值对钠钾结合的影响以及钠钾ATP酶E1构象中氢离子的电致移动,提供了这种机制的证据。