Kralj-Iglic V, Svetina S, Zeks B
Institute of Biophysics, Medical Faculty, University of Ljubljana, Slovenia.
Eur Biophys J. 1996;24(5):311-21. doi: 10.1007/BF00180372.
The interdependence of the lateral distribution of molecules which are embedded in a membrane (such as integral membrane proteins) and the shape of a cell with no internal structure (such as phospholipid vesicles or mammalian erythrocytes) has been studied. The coupling of the lateral distribution of the molecules and the cell shape is introduced by considering that the energy of the membrane embedded molecule at a given site of the membrane depends on the curvature of the membrane at that site. Direct interactions between embedded molecules are not considered. A simple expression for the interaction of the membrane embedded molecule with the local membrane curvature is proposed. Starting from this interaction, the consistently related expressions for the free energy and for the distribution function of the embedded molecules are derived. The equilibrium cell shape and the corresponding lateral distribution of the membrane embedded molecules are determined by minimization of the membrane free energy which includes the free energy of the membrane embedded molecules and the membrane elastic energy. The resulting inhomogeneous distribution of the membrane embedded molecules affects the cell shape in a nontrivial manner. In particular, it is shown that the shape corresponding to the absolute energy minimum at given cell volume and membrane area may be elliptically non-axisymmetric, in contrast to the case of a laterally homogeneous membrane where it is axisymmetric.
人们已经研究了嵌入膜中的分子（如整合膜蛋白）的横向分布与无内部结构的细胞（如磷脂囊泡或哺乳动物红细胞）形状之间的相互依存关系。通过考虑膜嵌入分子在膜的给定位置处的能量取决于该位置处膜的曲率，引入了分子横向分布与细胞形状之间的耦合。未考虑嵌入分子之间的直接相互作用。提出了膜嵌入分子与局部膜曲率相互作用的一个简单表达式。从这种相互作用出发，推导出了与自由能和嵌入分子分布函数始终相关的表达式。平衡细胞形状和膜嵌入分子的相应横向分布是通过使包括膜嵌入分子自由能和膜弹性能的膜自由能最小化来确定的。由此产生的膜嵌入分子的不均匀分布以一种复杂的方式影响细胞形状。特别地，结果表明，在给定细胞体积和膜面积下对应于绝对能量最小值的形状可能是椭圆非轴对称的，这与横向均匀膜的情况（其是轴对称的）形成对比。
