STRUCTURAL STUDIES OF FARNESYLATED RAS ASSOCIATED W/ MEMBRANE BILAYERS

六分枝杆菌载脂蛋白-III是一种可交换的166个残基 昆虫Manduca Sexta的载脂蛋白与脂质有关 循环系统内的运输过程。这是一个 脂质相关蛋白，但它不是跨膜蛋白。 以其水溶性的形式，这种蛋白质已经结晶， 结构采用五股螺旋束构象。脂类 联想被认为涉及一种剧烈的构象变化 其中螺旋束解体。由此产生的脂蛋白颗粒 被认为采用球状形状，外核为蛋白质 围绕着疏水类脂的内核。这种蛋白质 据推测，其水生区域指向 水环境及其对脂类的疏水区域 核心。记录了均一的15N的固体核磁共振波谱 玻璃板上脂双层中标记的载脂蛋白-III。这个 由此产生的15N化学位移光谱表明， 在15N粉末图案范围内的强度随增加 与典型粉末相比，？33不连续处的强度 图案分布。这一结果表明， 蛋白质以沿双层排列的螺旋轴定向 很正常。

M. sexta apolipophorin-III is a 166 residue exchangeable apolipoprotein from the insect Manduca Sexta involved in the lipid transport processes within the circulatory system. It is a lipid-associated protein, however it is not a transmembrane protein. In its water-soluble form, this protein has been crystallized, and the structure was found to adopt a five-helix bundle conformation. Lipid association is believed to involve a drastic conformational change wherein the helix bundle unravels. The resulting lipoprotein particle is believed to adopt a sphere-like shape with an outer core of protein surrounding an inner core of hydrophobic lipid. The protein presumably orients with hydrophylic regions directed towards the aqueous environment, and its hydrophobic regions toward the lipid core. Solid-state NMR spectra were recorded of the uniformly 15N labeled apolipophorin - III in lipid bilayers on glass plates. The resulting 15N chemical shift spectrum indicated a dispersion of intensities across the 15N powder pattern range with an increase of intensity at the ?33 discontinuity compared to the typical powder pattern distribution. This result indicates a portion of the sites in the protein orient with a helical axis aligned along the bilayer normal.