很多膜蛋白的X-射线晶体结构已被确定，但关于处在它们原始膜环境中的蛋白的直接结构信息却很少。
现在，一项将中子衍射、固体NMR光谱和分子动态模拟结合起来的研究，为包含S1-S4电压感应域（它们被膜蛋白用来感应膜电压变化并对其做出反应）的类脂双层膜的结构和水合提供了一幅详细的画面。可以看到，这些电压传感器采用跨膜取向，使周围的类脂双层发生小幅度变形，但变形幅度之大足以让水分子能够与膜发生相互作用，从而使带电残体发生水合，使跨膜电场成形，同时将能量和结构扰动保持到最小程度。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 462, 473-479 (26 November 2009) | doi:10.1038/nature08542
Structure and hydration of membranes embedded with voltage-sensing domains
Dmitriy Krepkiy1,8, Mihaela Mihailescu2,5,8, J. Alfredo Freites2,3, Eric V. Schow4, David L. Worcester2,5,6, Klaus Gawrisch7, Douglas J. Tobias3, Stephen H. White2,5 & Kenton J. Swartz1
1 Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
2 Department of Physiology and Biophysics, and Center for Biomembrane Systems,
3 Department of Chemistry and Institute for Surface and Interface Science,
4 Department of Physics and Astronomy and Institute for Genomics and Bioinformatics, University of California, Irvine, California 92697, USA
5 NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
6 Biology Division, University of Missouri, Columbia, Missouri 65211, USA
7 Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892, USA
8 These authors contributed equally to this work.
Despite the growing number of atomic-resolution membrane protein structures, direct structural information about proteins in their native membrane environment is scarce. This problem is particularly relevant in the case of the highly charged S1–S4 voltage-sensing domains responsible for nerve impulses, where interactions with the lipid bilayer are critical for the function of voltage-activated ion channels. Here we use neutron diffraction, solid-state nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics simulations to investigate the structure and hydration of bilayer membranes containing S1–S4 voltage-sensing domains. Our results show that voltage sensors adopt transmembrane orientations and cause a modest reshaping of the surrounding lipid bilayer, and that water molecules intimately interact with the protein within the membrane. These structural findings indicate that voltage sensors have evolved to interact with the lipid membrane while keeping energetic and structural perturbations to a minimum, and that water penetrates the membrane, to hydrate charged residues and shape the transmembrane electric field.
