Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
J Am Chem Soc. 2010 Feb 3;132(4):1200-1. doi: 10.1021/ja907936c.
The protein epsin is believed to play important roles in clathrin-mediated endocytosis, including generation of the high membrane curvature necessary for vesicle formation. Here we assess the basis for this hypothesis by systematically quantifying the curvature dependence of the area density of epsin N-terminal homology (ENTH) domain on cylindrical membranes of controlled curvature. In cylindrical tethers pulled from micropipet-aspirated giant unilamellar vesicles, repartitioning of membrane-bound ENTH from vesicles onto highly curved membranes was observed by fluorescence microscopy. First-order thermodynamic theory used to analyze our data yielded the first measurement of Leibler's thermodynamic curvature-composition coupling coefficient to be reported for an endocytic accessory protein. Our results highlight the possibility that epsin contributes to cellular membrane curvature sensing and generation, and we believe that our method will provide useful contributions toward the goal of relating molecular descriptions of interactions to macroscopic membrane remodeling in cells and identifying and characterizing roles for proteins in these processes.
蛋白 epsin 被认为在网格蛋白介导的胞吞作用中发挥重要作用，包括产生形成囊泡所需的高膜曲率。在这里，我们通过系统地量化 epsin N 端同源（ENTH）域在受控曲率圆柱膜上的面积密度对该假设进行评估。在从微管抽吸的巨大单层囊泡中拉出的圆柱系绳中，通过荧光显微镜观察到膜结合的 ENTH 从囊泡重新分配到高度弯曲的膜上。用于分析我们数据的一阶热力学理论得出了第一个被报道的网格蛋白附属蛋白的 Leibler 热力学曲率-组成耦合系数的测量值。我们的结果强调了 epsin 可能有助于细胞的膜曲率感应和产生，我们相信我们的方法将为将相互作用的分子描述与细胞中的宏观膜重塑联系起来以及确定和描述这些过程中的蛋白质的作用做出有益的贡献。
