Department of Chemistry, 1274 University of Oregon, Eugene, OR 97403-1274, USA.
Biochem Biophys Res Commun. 2012 Oct 5;426(4):585-9. doi: 10.1016/j.bbrc.2012.08.131. Epub 2012 Sep 4.
The sculpting of membranes into highly curved vesicles is central to intracellular cargo trafficking, yet the mechanical activities of trafficking proteins remain poorly understood. Using an optical trap based assay that measures in vitro membrane response to imposed deformations, we examined the behavior of the two human paralogs of Sar1, a key component of the COPII family of vesicle coat proteins. Like their yeast counterpart, the human Sar1 proteins can lower the mechanical rigidity of the membranes to which they bind. Unlike the yeast Sar1, the rigidity is not a monotonically decreasing function of concentration. At high concentrations, we find increased bending rigidity and decreased protein mobility. These features imply a model in which protein clustering governs membrane mechanical properties.
将膜塑造成高度弯曲的小泡是细胞内货物运输的核心，然而运输蛋白的机械活动仍知之甚少。使用一种基于光阱的测定方法，该方法测量了体外膜对施加的变形的反应，我们研究了 Sar1 的两种人类同源物的行为，Sar1 是 COPII 囊泡包被蛋白家族的关键组成部分。与酵母 Sar1 一样，人类 Sar1 蛋白可以降低与其结合的膜的机械刚性。与酵母 Sar1 不同，刚性不是浓度的单调递减函数。在高浓度下，我们发现弯曲刚性增加和蛋白流动性降低。这些特征意味着一种模型，其中蛋白聚类控制膜的机械性能。
