Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Denmark.
J Struct Biol. 2011 May;174(2):296-306. doi: 10.1016/j.jsb.2010.12.004. Epub 2010 Dec 21.
The Na+,K+-ATPase belongs to the P-ATPase family, whose characteristic property is the formation of a phosphorylated intermediate. The enzyme is also a defined target for cardiotonic steroids which inhibit its functional activity and initiate intracellular signaling. Here we describe the 4.6 Å resolution crystal structure of the pig kidney Na+,K+-ATPase in its phosphorylated form stabilized by high affinity binding of the cardiotonic steroid ouabain. The steroid binds to a site formed at transmembrane segments αM1-αM6, plugging the ion pathway from the extracellular side. This structure differs from the previously reported low affinity complex with potassium. Most importantly, the A domain has rotated in response to phosphorylation and αM1-2 move towards the ouabain molecule, providing for high affinity interactions and closing the ion pathway from the extracellular side. The observed re-arrangements of the Na+,K+-ATPase stabilized by cardiotonic steroids may affect protein-protein interactions within the intracellular signal transduction networks.
钠钾泵属于 P 型 ATP 酶家族，其特征在于形成磷酸化中间产物。该酶也是强心甾体的明确靶点，后者可抑制其功能活性并引发细胞内信号转导。在此，我们描述了猪肾钠钾泵在其磷酸化形式下的 4.6 Å 分辨率晶体结构，该结构通过强心甾体哇巴因的高亲和力结合而稳定。该甾体结合到由跨膜片段 αM1-αM6 形成的位点，从而阻塞从细胞外进入的离子通道。该结构与先前报道的低钾亲和力复合物不同。最重要的是，A 结构域响应磷酸化而旋转，并且 αM1-2 向哇巴因分子移动，从而实现高亲和力相互作用并从细胞外封闭离子通道。通过强心甾体稳定的钠钾泵的观察到的重排可能会影响细胞内信号转导网络内的蛋白质-蛋白质相互作用。
