MOLECULAR BASIS FOR ION CHANNEL FUNCTION

细胞中约有一半的蛋白质与脂质有关。 双层，他们可以说是执行一些最有趣的， 细胞中的重要功能。例如，离子通道控制着细胞内的 细胞环境和促进神经信号，而膜 受体对于控制细胞代谢至关重要。 大分子是病毒感染和免疫系统中的关键因素， 反应也吃膜蛋白。不幸的是， 已知的结构，分子操作和组装 膜蛋白这主要是因为， 它可以产生水溶性蛋白质的结构信息， 晶体学和高分辨率NMR通常在应用于 膜蛋白这可能是一个巨大的回报，当这样的 结构被理解，因为设计新的 针对这些特定结构和过程的药物 proteins.这种结构信息也将有助于分子 了解多种遗传疾病。 目前，没有电压门控通道， 导致门控已经清楚地阐明，和目标的 拟议的研究是确定导致 电压门控和两个膜离子通道的调节。结构 和门控机制的丙甲霉素将进行研究，一个小肽， 在细胞膜中产生电压依赖的电导。这是一个模型， 更大的电压门控通道，它也属于一个更广泛的群体， 膜活性肽具有重要的抗生素活性。一 第二个要研究的蛋白质是磷脂蛋白。这种蛋白质 在心肌中发现，它是主要的肌膜基质， 环AMP依赖性蛋白激酶A和蛋白激酶C。磷莱曼 是一种8KDa的跨膜蛋白，可形成电压激活的阴离子 频道通过表征这些分子的结构和分子门控， 渠道，预计有关的基本信息 膜离子转运的性质和相关的结构变化 将获得具有选通和信道调节的。 拟议的工作将利用光谱技术，如EPR， 高分辨率NMR和固态NMR来确定这些化合物的结构 通道以及与门控和共价修饰相关的变化。 自旋探针将被纳入这些通道的EPR实验 使用合成技术和定点诱变。

Approximately half the proteins present in cells are associated with lipid bilayers, and they arguably perform some of the most interesting and important functions in the cell. For example, ion channels control the cellular environment and facilitate nerve signaling, while membrane receptors are critical for the control of cellular metabolism. Macromolecules that are key elements in viral infection and the immune response ate also membrane proteins. Unfortunately, relatively little is known regarding the structures, molecular operation and assembly of membrane proteins. This is primarily a result of the fact that approaches that can yield structural information on water-soluble proteins such as crystallography and high resolution NMR generally fail when applied to membrane proteins. The is potentially an enormous payoff when such structures are understood, because of the potential to design new pharmaceuticals that target specific structures and processes in these proteins. This structural information will also facilitate a molecular understanding of numerous genetic diseases. Presently, there are no voltage-gated channels where the molecular events leading to gating have been clearly elucidated, and the objective of the proposed research is to define the molecular mechanisms that lead to voltage-gating and regulation of two membrane ion channels. The structure and gating mechanism of alamethicin will be studied, a small peptide that produces a voltage-dependent conductance in membranes. It is a model for larger voltage-gated channels, and it also belongs to a wider group of membrane active peptides that have important antibiotic activities. A second protein that will be studied is phospholemman. This protein is found in the myocardium and it is the major sarcolemmal substrate of cyclic AMP dependent protein kinase A and protein kinase C. Phospholemman is an 8 KDa transmembrane protein that forms a voltage-activated anion channel. By characterizing the structure and molecular gating of these channels, it is anticipated that fundamental information regarding the nature of membrane ion transport and the structural changes associated with gating and channel regulation will be obtained. The proposed work will make use of spectroscopic techniques such as EPR, high resolution NMR and solid-state NMR to define the structures of these channels and the changes associated with gating and covalent modification. Spin-probes will be incorporated into these channels for EPR experiments using synthetic techniques and site-directed mutagenesis.