Lateral mobility of proteins in liquid membranes revisited
Lateral mobility of proteins in liquid membranes revisited
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DOI：
10.1073/pnas.0511026103
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发表时间：
2006-02-14
影响因子：
11.1
通讯作者：
Urbach, W
中科院分区：
文献类型：
--
作者：
Gambin, Y;Lopez-Esparza, R;Urbach, W
跨膜蛋白的生物学功能与其插入密切相关，而这通常是通过其侧向移动性来研究的。30多年来，人们一直认为从这类实验中几乎无法提取出有关扩散物体大小的任何信息。事实上，由萨夫曼（Saffman）和德尔布吕克（Delbruck）提出的流体动力学模型预测，扩散系数D与蛋白质半径R呈微弱的对数关系。尽管该模型被广泛应用，但其有效性从未得到彻底研究。为了检验这一模型，我们测量了多种肽和跨膜蛋白的扩散系数，这些物质被嵌入1 - 硬脂酰 - 2 - 油酰 - sn - 甘油 - 3 - 磷酸胆碱（SOPC）的巨型单层囊泡中，或嵌入厚度可调的模型双层膜中。我们在这项工作中表明，对于几种大小差异较大的整合蛋白，扩散系数与蛋白质的尺寸密切相关。一个启发式模型得出了一个类似斯托克斯（Stokes）的D表达式（D与1/R成正比），该表达式与文献数据以及我们的数据都相符。因此，扩散测量是一种快速且富有成效的方法；它可以确定蛋白质的寡聚化程度，或研究双层膜内的脂质 - 蛋白质和蛋白质 - 蛋白质相互作用。
The biological function of transmembrane proteins is closely related to their insertion, which has most often been studied through their lateral mobility. For > 30 years, it has been thought that hardly any information on the size of the diffusing object can be extracted from such experiments. Indeed, the hydrodynamic model developed by Saffman and Delbruck predicts a weak, logarithmic dependence of the diffusion coefficient D with the radius R of the protein. Despite widespread use, its validity has never been thoroughly investigated. To check this model, we measured the diffusion coefficients of various peptides and transmembrane proteins, incorporated into giant unilamellar vesicles of 1-stearoyl-2-oleoylsn-glycero-3-phosphocholine (SOPC) or in model bilayers of tunable thickness. We show in this work that, for several integral proteins spanning a large range of sizes, the diffusion coefficient is strongly linked to the protein dimensions. A heuristic model results in a Stokes-like expression for D, (D proportional to 1/R), which fits literature data as well as ours. Diffusion measurement is then a fast and fruitful method; it allows determining the oligomerization degree of proteins or studying lipid-protein and protein-protein interactions within bilayers.