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arXiv 1802.01067physics.bio-phq-bio.SC
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理论膜Phase Diagram的计算和相在脂筏介导的蛋白质组织中的作用

Computation of a Theoretical Membrane Phase Diagram, and the Role of Phase in Lipid Raft-Mediated Protein Organization

Eshan D. Mitra, Samuel C. Whitehead, David Holowka, Barbara Baird, James P. Sethna

摘要:

脂相异质性在质膜被认为是至关重要的细胞信号的许多方面,但参与膜域,如“脂筏”的物理基础仍然存在争议。在这里,我们考虑一个晶格模型产生的相图,其中包括几个国家提出的相关的细胞膜,包括微乳液-这可能与膜曲率-和伊辛临界行为。使用基于神经网络的机器学习方法,我们计算了这个晶格模型的完整相图。我们在肥大细胞中信号传导起始事件的背景下分析了该相图的选定区域:膜锚定酪氨酸激酶Lyn募集到IgE-FcεRI受体的跨膜簇。我们发现,微乳液和伊辛临界状态下的模型膜系统可以介导大致相等水平的激酶募集(结合能~ -0.6 kBT),而接近三临界点的膜可以介导更强的激酶募集(~ 1.7 kBT)。通过在一个单一的理论框架内比较几个模型的脂质异质性,这项工作指出现有模型之间的可测试的差异。我们还建议作为一个新的可能性的膜结构域的基础上,促进优先分配的信号成分的三临界点。

英文摘要:

Lipid phase heterogeneity in the plasma membrane is thought to be crucial for many aspects of cell signaling, but the physical basis of participating membrane domains such as "lipid rafts" remains controversial. Here we consider a lattice model yielding a phase diagram that includes several states proposed to be relevant for the cell membrane, including microemulsion - which can be related to membrane curvature - and Ising critical behavior. Using a neural network-based machine learning approach, we compute the full phase diagram of this lattice model. We analyze selected regions of this phase diagram in the context of a signaling initiation event in mast cells: recruitment of the membrane-anchored tyrosine kinase Lyn to a cluster of transmembrane of IgE-FcεRI receptors. We find that model membrane systems in microemulsion and Ising critical states can mediate roughly equal levels of kinase recruitment (binding energy ~ -0.6 kBT), whereas a membrane near a tricritical point can mediate much stronger kinase recruitment (-1.7 kBT). By comparing several models for lipid heterogeneity within a single theoretical framework, this work points to testable differences between existing models. We also suggest the tricritical point as a new possibility for the basis of membrane domains that facilitate preferential partitioning of signaling components.

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