One-dimensional crystals of (Na+ + K+)-ATPase dimers.
One-dimensional crystals of (Na+ + K+)-ATPase dimers.
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(Na K )-ATP酶二聚体的一维晶体。
DOI：
10.1016/0005-2736(86)90063-5
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
Kreman,M
中科院分区：
文献类型：
--
作者：
Zampighi,G;Simon,SA;Kyte,J;Kreman,M
纯化的 (Na++ K+)-ATP 酶制品含有膜片段和长而起伏的圆柱形结构。这些结构被描述为膜碎片的边缘。我们使用负染色、薄片切片和冷冻断裂蚀刻电子显微镜分析了这些结构，并首次描述了它们的结构。每个圆柱体的宽度为 12–19 nm，由未染色的核心组成，从该核心的两侧投射出一排间隔 5–6 nm 的不同颗粒。每个圆柱形结构被解释为(Na++ K+)-ATP酶分子的(αβ)2二聚体的线性聚合物。因此，从两侧突出的颗粒是酶分子的细胞质结构域，而跨膜结构域形成圆柱体的未染色核心。从二聚体在圆柱体中堆积的考虑，我们得出结论，细胞质结构域的横截面积应该大于跨膜结构域的横截面积。我们的结果与 (αβ) 原体是酶的天然状态的假设一致。在级分中观察到的 (αβ)2 二聚体是纯化过程中发生的二次聚集过程的结果。
Preparations of purified (Na++ K+)-ATPase contain both fragments of membranes and long and undulating cylindrical structures. These structures have been described as edgeways of membrane fragments. We have analyzed these structures using negative staining, thin sectioning and freeze-fracture-etch electron microscopy and describe their structure for the first time. Each cylinder is 12–19 nm in width and is comprised of an unstained core from which rows of distinct particles spaced 5–6 nm apart project on both sides. Each cylindrical structure was interpreted as a linear polymer of (αβ) 2 dimers of (Na++ K+)-ATPase molecules. Therefore, the particles that project from both sides are the cytoplasmic domains of the molecules of the enzyme, whereas the membrane-spanning domains form the unstained core of the cylinder. From considerations of the packing of the dimers in the cylinder we conclude that the cross-sectional area of the cytoplasmic domain should be larger than that of the membrane-spanning domain. Our results are consistent with the hypothesis that the (αβ) protomer is the native state of the enzyme. The (αβ) 2 dimers observed in the fractions are the result of a secondary aggregation process occurring during the purification procedure.