Skriver E, Kavéus U, Hebert H, Maunsbach A B
Department of Cell Biology, University of Aarhus, Denmark.
J Struct Biol. 1992 Mar-Apr;108(2):176-85. doi: 10.1016/1047-8477(92)90017-5.
The three-dimensional structure of Na,K-ATPase has been analyzed with electron microscopy and image processing. The enzyme, purified from pig kidney outer medulla, was arranged in a new form of tetragonal two-dimensional membrane crystals after incubation with cobalt-tetrammine-ATP, a stable MgATP complex analogue. Each continuous protein domain, as delineated by negative stain, consists of two alpha beta-protomers related by a dyad axis. The two rod-like regions are connected by a bridge displaced about 20 A away from the center of the structure toward the lipid bilayer. The domain connecting the two promoters is more constricted and closer to the center of the structure in the Co(NH3)4ATP-induced crystals than in the vanadate-induced p21 crystals. These observations suggest that the difference between previously analyzed dimers of two-dimensional p21 crystals induced with vanadate/magnesium and dimers of p4 crystals induced with Co(NH3)4ATP reflects two different conformational states of the enzyme.
利用电子显微镜和图像处理技术对钠钾-ATP酶的三维结构进行了分析。从猪肾外髓质纯化得到的该酶，在与钴四胺-ATP（一种稳定的MgATP复合类似物）孵育后，排列成一种新的四方二维膜晶体形式。经负染勾勒出的每个连续蛋白质结构域由通过二元轴相关的两个αβ-原聚体组成。两个棒状区域由一个桥连接，该桥从结构中心向脂质双层偏移约20埃。与钒酸盐诱导的p21晶体相比，在Co(NH3)4ATP诱导的晶体中，连接两个原聚体的结构域更狭窄且更靠近结构中心。这些观察结果表明，先前分析的由钒酸盐/镁诱导的二维p21晶体二聚体与由Co(NH3)4ATP诱导的p4晶体二聚体之间的差异反映了该酶的两种不同构象状态。
