Effect of line tension on the lateral organization of lipid membranes
Effect of line tension on the lateral organization of lipid membranes
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DOI：
10.1074/jbc.m706162200
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发表时间：
2007-11-16
影响因子：
4.8
通讯作者：
Schwille, Petra
中科院分区：
文献类型：
--
作者：
Garcia-Saez, Ana J.;Chiantia, Salvatore;Schwille, Petra
细胞膜的组织和功能的原理目前还没有很好的理解。筏假说认为细胞膜中存在结构域或筏，它们充当蛋白质和脂质平台。它们在重要的细胞过程中发挥功能性作用，如蛋白质分选或细胞信号传导等。理论工作表明，在域边缘的界面能，也被称为线张力，是一个关键参数确定域大小的分布，但很少有证据表明，线张力如何影响膜组织。我们已经调查的影响，线张力的形成和稳定的液体有序结构域的模型脂双层筏状组合物通过延时共聚焦显微镜耦合到原子力显微镜。我们改变了两个阶段之间的疏水性失配，因此线张力，通过修改的厚度与不同的酰基链长度的磷脂酰胆碱的无序相。畴形成的温度、畴生长的动力学和畴尺寸的分布强烈地依赖于畴与周围膜之间的厚度差，该厚度差与线张力有关。当考虑从理论模型计算的线张力时，我们的结果揭示了畴形成温度和畴生长速率随线张力的线性增加。域出芽也被证明取决于高度不匹配。我们的实验大大有助于我们的知识，控制膜组织的物理化学参数。重要的是，观察到的一般趋势可以扩展到细胞膜。
The principles of organization and functioning of cellular membranes are currently not well understood. The raft hypothesis suggests the existence of domains or rafts in cell membranes, which behave as protein and lipid platforms. They have a functional role in important cellular processes, like protein sorting or cell signaling, among others. Theoretical work suggests that the interfacial energy at the domain edge, also known as line tension, is a key parameter determining the distribution of domain sizes, but there is little evidence of how line tension affects membrane organization. We have investigated the effects of the line tension on the formation and stability of liquid ordered domains in model lipid bilayers with raft-like composition by means of time-lapse confocal microscopy coupled to atomic force microscopy. We varied the hydrophobic mismatch between the two phases, and consequently the line tension, by modifying the thickness of the disordered phase with phosphatidylcholines of different acyl chain length. The temperature of domain formation, the dynamics of domain growth, and the distribution of domain sizes depend strongly on the thickness difference between the domains and the surrounding membrane, which is related to line tension. When considering line tension calculated from a theoretical model, our results revealed a linear increase of the temperature of domain formation and domain growth rate with line tension. Domain budding was also shown to depend on height mismatch. Our experiments contribute significantly to our knowledge of the physical-chemical parameters that control membrane organization. Importantly, the general trends observed can be extended to cellular membranes.