纽带蛋白及其与微丝和膜结合的研究

 用落球粘度计测量低剪切粘度的方法研究了纽带蛋白-肌动蛋白的相互作用。与以前关于纽带蛋白可使肌动蛋白粘度降低并推测它抑制微丝间相互作用的报道不同,10—50μg/ml的纽带蛋白引起肌动蛋白细丝溶液粘度略有增加。电镜观察表明,由于纽带蛋白的作用,肌动蛋白丝聚集成束。 远紫外圆二色谱显示,在pH7.0下,220和207nm处呈双负峰,190nm处有一正峰。按三波长法计算,其α螺旋和β折叠含量分别占41％和22％。研究了pH,磷脂和去垢剂对其构象的影响。疏水性结合的和水溶性的纽带蛋白相比,存在少量构象差别。联系这一蛋白处在细胞骨架与质膜相联系的特殊位置,推测在体内,纽带蛋白与脂结合后也可能发生类似的构象变化。

STUDIES ON VINCULIN AND ITS BINDING WITH ACTIN FILAMENTS AND LIPIDS IN VITRO

Interactions between purified vinculin and actin were studied by means of low shear viscometry with the falling ball viscometer and electron microscopy. With the addition of vinculin of 10-50μg/mI, an increase of the viscosity of filamen-tal actin solution has been obtained. The electron micrographs of negativily stained preparations showed that there were filament bundlesin actin samples containing vinculin. The results are not compatible with the previously suggested role of vinculin inhibition of actin filament-filament interaction.The far UV CD spectrum of vinculin showed a double minimum at 220 and 207 nm and a maximum at 190 nm. Analysis in terms of Goren et al. resulted in α-helical and β-structure contents of 41% and 22% respectively. Conforma-tional changes induced either by pH or by addition of detergents and lipids were summerized. The studies were consistent with the fact that vinculin is localized ot the site where the cytoskeleton is accociated with the plasma membrune. It may adapt a structure in binding with lipid and may possess some activities not apparent in solution