Institut Pasteur de Montevideo, Calle Mataojo 2020, CP 11400 Montevideo, Uruguay.
J Chem Phys. 2012 Jan 7;136(1):015103. doi: 10.1063/1.3672704.
Cell membranes are constitutively composed of thousands of different lipidic species, whose specific organization leads to functional heterogeneities. In particular, sphingolipids, cholesterol and some proteins associate among them to form stable nanoscale domains involved in recognition, signaling, membrane trafficking, etc. Atomic-detail information in the nanometer/second scale is still elusive to experimental techniques. In this context, molecular simulations on membrane systems have provided useful insights contributing to bridge this gap. Here we present the results of a series of simulations of biomembranes representing non-raft and raft-like nano-sized domains in order to analyze the particular structural and dynamical properties of these domains. Our results indicate that the smallest (5 nm) raft domains are able to preserve their distinctive structural and dynamical features, such as an increased thickness, higher ordering, lower lateral diffusion, and specific lipid-ion interactions. The insertion of a transmembrane protein helix into non-raft, extended raft-like, and raft-like nanodomain environments result in markedly different protein orientations, highlighting the interplay between the lipid-lipid and lipid-protein interactions.
细胞膜由数千种不同的脂质物种组成，其特定的组织导致了功能的异质性。特别是，鞘脂、胆固醇和一些蛋白质在它们之间相互作用，形成了参与识别、信号转导、膜运输等的稳定的纳米尺度结构域。在纳米/秒的尺度上的原子细节信息仍然难以用实验技术获得。在这种情况下，对膜系统的分子模拟提供了有用的见解，有助于弥合这一差距。本文介绍了一系列模拟非筏状和筏状纳米尺寸结构域的生物膜的结果，以分析这些结构域的特定结构和动力学特性。结果表明，最小的(5nm)筏状结构域能够保持其独特的结构和动力学特征，如厚度增加、有序性提高、侧向扩散降低以及特定的脂质-离子相互作用。将跨膜蛋白螺旋插入非筏状、扩展的筏状和筏状纳米结构域环境中，会导致明显不同的蛋白取向，突出了脂质-脂质和脂质-蛋白相互作用之间的相互作用。
