Božič Bojan, Das Sovan L, Svetina Saša
Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
Soft Matter. 2015 Mar 28;11(12):2479-87. doi: 10.1039/c4sm02289k.
Cell membrane proteins, both bound and integral, are known to preferentially accumulate at membrane locations with curvatures favorable to their shape. This is mainly due to the curvature dependent interaction between membrane proteins and their lipid environment. Here, we analyze the effects of the protein-lipid bilayer interaction energy due to mismatch between the protein shape and the principal curvatures of the surrounding bilayer. The role of different macroscopic parameters that define the interaction energy term is elucidated in relation to recent experiment in which the lateral distribution of a membrane embedded protein potassium channel KvAP is measured on a giant unilamellar lipid vesicle (reservoir) and a narrow tubular extension - a tether - kept at constant length. The dependence of the sorting ratio, defined as the ratio between the areal density of the protein on the tether and on the vesicle, on the inverse tether radius is influenced by the strength of the interaction, the intrinsic shape of the membrane embedded protein, and its abundance in the reservoir. It is described how the values of these constants can be extracted from experiments. The intrinsic principal curvatures of a protein are related to the tether radius at which the sorting ratio attains its maximum value. The estimate of the principal intrinsic curvature of the protein KvAP, obtained by comparing the experimental and theoretical sorting behavior, is consistent with the available information on its structure.
已知结合型和整合型细胞膜蛋白会优先聚集在曲率与其形状相适配的膜位置。这主要归因于膜蛋白与其脂质环境之间依赖于曲率的相互作用。在此，我们分析了由于蛋白质形状与周围双层膜的主曲率不匹配而导致的蛋白质 - 脂质双层相互作用能的影响。结合最近的一项实验阐明了定义相互作用能项的不同宏观参数的作用，在该实验中，测量了嵌入膜中的蛋白质钾通道KvAP在巨型单层脂质囊泡（储存器）和保持恒定长度的狭窄管状延伸部分——系链上的横向分布。分选比定义为系链上和囊泡上蛋白质的面密度之比，其对系链半径倒数的依赖性受相互作用强度、嵌入膜中的蛋白质的固有形状及其在储存器中的丰度影响。文中描述了如何从实验中提取这些常数的值。蛋白质的固有主曲率与分选比达到最大值时的系链半径相关。通过比较实验和理论分选行为获得的蛋白质KvAP的主固有曲率估计值与关于其结构的现有信息一致。
