Stein W D, Lieb W R, Karlish S J, Eilam Y
Proc Natl Acad Sci U S A. 1973 Jan;70(1):275-8. doi: 10.1073/pnas.70.1.275.
A new model is proposed for the system that actively transports sodium and potassium ions across animal-cell membranes. The model is based on the physical and chemical properties of transport-associated adenosine triphosphatase (EC 3.6.1.3) and on the kinetics of ion movements mediated by the system. Transport is postulated to occur by internal transfer of cations across a protein tetramer embedded in the cell membrane. The protein tetramer can exist in either of two forms of identical energy; transport occurs as a result of the sequential "flipping" from one conformation to the other. The conformation change results in the interchanging of the affinities of cation-binding sites associated with different sub-units of the tetramer, with a concomitant splitting of adenosine triphosphate.
提出了一种新的动物细胞膜主动运输钠和钾离子系统的模型。该模型基于与运输相关的三磷酸腺苷酶(EC 3.6.1.3)的物理和化学性质以及由该系统介导的离子运动动力学。推测运输是通过阳离子在嵌入细胞膜的蛋白质四聚体中的内部转移而发生的。蛋白质四聚体可以以两种能量相同的形式存在;运输是由于从一种构象到另一种构象的顺序“翻转”而发生的。构象变化导致与四聚体不同亚基相关的阳离子结合位点的亲和力互换,同时伴随着三磷酸腺苷的分解。