You H X, Yu L, Qi X
Department of Cell Biology, Neurobiology, and Anatomy, University of Cincinnati College of Medicine, OH 45267-0521, USA.
FEBS Lett. 2001 Aug 10;503(1):97-102. doi: 10.1016/s0014-5793(01)02700-4.
The enzymatic activity of glucosylceramidase depends on the presence of saposin C (Sap C) and acidic phospholipid-containing membranes. In order to delineate the mechanism underlying Sap C stimulation of the enzyme activity, it is important to understand how Sap C interacts with phospholipid membranes. We studied the dynamic process of Sap C interaction with planar phospholipid membranes, in real time, using atomic force microscopy (AFM). The phospholipid membrane underwent restructuring upon addition of Sap C. The topographic characteristics of the membrane restructuring include the appearance of patch-like new features, initially emerged at the edge of phospholipid membranes and extended laterally with time. Changes in the image contrast of the phospholipid membrane observed after the Sap C addition indicate that a new phase of lipid-protein structure has formed during membrane restructuring. The process of membrane restructuring is dynamic, commencing shortly after Sap C addition, and continuing throughout the duration of AFM imaging (about 30 min, sometimes over 1 h). This study demonstrated the potential of AFM real-time imaging in studying protein-membrane interactions.
葡萄糖神经酰胺酶的酶活性取决于鞘脂激活蛋白C（Sap C）和含酸性磷脂的膜的存在。为了阐明Sap C刺激酶活性的潜在机制，了解Sap C如何与磷脂膜相互作用很重要。我们使用原子力显微镜（AFM）实时研究了Sap C与平面磷脂膜相互作用的动态过程。添加Sap C后，磷脂膜发生了重构。膜重构的形貌特征包括出现斑块状新特征，最初出现在磷脂膜边缘，随后随时间横向扩展。添加Sap C后观察到的磷脂膜图像对比度变化表明，在膜重构过程中形成了脂质-蛋白质结构的新相。膜重构过程是动态的，在添加Sap C后不久开始，并在AFM成像的整个持续时间（约30分钟，有时超过1小时）内持续进行。这项研究证明了AFM实时成像在研究蛋白质-膜相互作用方面的潜力。
