專題：Nature報(bào)道
鈉-鉀ATP酶是一種由ATP提供動力的離子泵,，能為鈉離子和鉀離子在動物細(xì)胞的胞質(zhì)膜上形成濃度梯度,。鈉離子被從細(xì)胞中輸出，同時鉀離子被輸入細(xì)胞中,，產(chǎn)生用于很多重要生物過程,、如神經(jīng)細(xì)胞的動作電位的濃度梯度。
現(xiàn)在,，來自鯊魚直腸腺（與人的直腸腺有高度的同源性）的這種蛋白的晶體結(jié)構(gòu)已被以2.4埃的分辨率確定。該結(jié)構(gòu)可幫助澄清關(guān)于這種蛋白作用機(jī)制的很多細(xì)節(jié),，并且還將有助于對心臟病的認(rèn)識和治療,，因?yàn)閺?qiáng)心苷是鈉-鉀泵的抑制劑。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 459, 446-450 (21 May 2009) | doi:10.1038/nature07939; Received 30 July 2008; Accepted 26 February 2009
Crystal structure of the sodium–potassium pump at 2.4 Å resolution
Takehiro Shinoda1, Haruo Ogawa1, Flemming Cornelius2 & Chikashi Toyoshima1
1 Institute of Molecular and Cellular Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
2 Department of Physiology and Biophysics, University of Aarhus, DK-8000 Aarhus C, Denmark
Sodium–potassium ATPase is an ATP-powered ion pump that establishes concentration gradients for Na+ and K+ ions across the plasma membrane in all animal cells by pumping Na+ from the cytoplasm and K+ from the extracellular medium1, 2. Such gradients are used in many essential processes, notably for generating action potentials. Na+, K+-ATPase is a member of the P-type ATPases, which include sarcoplasmic reticulum Ca2+-ATPase and gastric H+, K+-ATPase, among others, and is the target of cardiac glycosides. Here we describe a crystal structure of this important ion pump, from shark rectal glands, consisting of - and -subunits and a regulatory FXYD protein3, 4, all of which are highly homologous to human ones. The ATPase was fixed in a state analogous to E22K+Pi, in which the ATPase has a high affinity for K+ and still binds Pi, as in the first crystal structure of pig kidney enzyme at 3.5 Å resolution5. Clearly visualized now at 2.4 Å resolution are coordination of K+ and associated water molecules in the transmembrane binding sites and a phosphate analogue (MgF4 2-) in the phosphorylation site. The crystal structure shows that the -subunit has a critical role in K+ binding (although its involvement has previously been suggested6, 7, 8) and explains, at least partially, why the homologous Ca2+-ATPase counter-transports H+ rather than K+, despite the coordinating residues being almost identical.
