Meerschaert Rebecca L, Kelly Christopher V
Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA.
Eur Biophys J. 2015 May;44(4):227-33. doi: 10.1007/s00249-015-1017-x. Epub 2015 Mar 28.
The addition of trace molecules into membranes can significantly alter the morphology of the co-existing liquid phases and lipid phase transition temperature. Membrane additives may affect lipid phase dynamics through preferentially partitioning to the boundary between lipid phases or preferentially mixing into one lipid phase. The characteristic differences between these mechanisms are demonstrated here in a minimalistic nearest neighbor model to provide a framework for how slight changes to membrane composition may affect lipid-phase-dependent processes, such as lipid-raft formation, immunological signaling, and molecular sorting preceding endocytosis with coexisting liquid phases. Within the low mole fractions explored here (≤3 mol%), increasing the additive concentration linearly changed the phase miscibility temperature. Rotationally asymmetric Janus particles reduced the miscibility transition temperature for all fractions and degree of phase polarization. Rotationally symmetric additives, however, either increased or decreased the phase miscibility temperature depending on the phase preference of the additive. While most experimental molecules may contain aspects of both of these idealized additives, this model provides a broad framework to quantify the effects of membrane additives in regard to lipid phase preference, lipid-raft association, and contribution to lipid phase-dependent molecular sorting.
向膜中添加微量分子可显著改变共存液相的形态和脂质相变温度。膜添加剂可能通过优先分配到脂质相之间的边界或优先混入一个脂质相来影响脂质相动力学。本文在一个简约的最近邻模型中展示了这些机制之间的特征差异，以提供一个框架，说明膜组成的微小变化如何影响脂质相依赖的过程，如脂筏形成、免疫信号传导以及内吞作用前与共存液相相关的分子分选。在此处探索的低摩尔分数范围内（≤3 mol%），增加添加剂浓度会线性改变相混溶温度。旋转不对称的Janus颗粒降低了所有分数下的混溶转变温度和相极化程度。然而，旋转对称添加剂根据添加剂的相偏好会升高或降低相混溶温度。虽然大多数实验分子可能兼具这两种理想化添加剂的某些方面，但该模型提供了一个广泛的框架，以量化膜添加剂在脂质相偏好、脂筏缔合以及对脂质相依赖的分子分选的贡献方面的影响。
