Ursell Tristan S, Klug William S, Phillips Rob
Department of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.
Proc Natl Acad Sci U S A. 2009 Aug 11;106(32):13301-6. doi: 10.1073/pnas.0903825106. Epub 2009 Jul 20.
Cellular membranes are a heterogeneous mix of lipids, proteins and small molecules. Special groupings enriched in saturated lipids and cholesterol form liquid-ordered domains, known as "lipid rafts," thought to serve as platforms for signaling, trafficking and material transport throughout the secretory pathway. Questions remain as to how the cell maintains small fluid lipid domains, through time, on a length scale consistent with the fact that no large-scale phase separation is observed. Motivated by these examples, we have utilized a combination of mechanical modeling and in vitro experiments to show that membrane morphology plays a key role in maintaining small domain sizes and organizing domains in a model membrane. We demonstrate that lipid domains can adopt a flat or dimpled morphology, where the latter facilitates a repulsive interaction that slows coalescence and helps regulate domain size and tends to laterally organize domains in the membrane.
细胞膜是脂质、蛋白质和小分子的异质混合物。富含饱和脂质和胆固醇的特殊聚集体形成了液序结构域，即所谓的“脂筏”，被认为是整个分泌途径中信号传导、运输和物质转运的平台。关于细胞如何在一段时间内维持与未观察到大规模相分离这一事实相一致的小尺寸流体脂质结构域，仍然存在问题。受这些例子的启发，我们结合了力学建模和体外实验，以表明膜形态在维持模型膜中的小结构域尺寸和组织结构域方面起着关键作用。我们证明脂质结构域可以呈现扁平或凹陷的形态，其中后者促进了一种排斥相互作用，减缓了聚结并有助于调节结构域大小，并且倾向于在膜中横向组织结构域。
