Mechanics of curved plasma membrane vesicles:: Resting shapes, membrane curvature, and in-plane shear elasticity
Mechanics of curved plasma membrane vesicles:: Resting shapes, membrane curvature, and in-plane shear elasticity
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DOI：
10.1115/1.1865197
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发表时间：
2005-04-01
影响因子：
1.7
通讯作者：
Schmid-Schönbein, GW
中科院分区：
文献类型：
--
作者：
Kosawada, T;Inoue, K;Schmid-Schönbein, GW
高度弯曲的细胞膜结构，如质膜囊泡（coveolae）和网格蛋白包覆的凹坑，促进了许多细胞功能，包括膜受体的聚集和内皮细胞特异性细胞外大分子的运输。当质膜被拉伸并受其曲率变化时，这些结构会受到较大的机械变形。为了提高我们对等离子体囊泡的理解，我们需要提高对高膜曲率区域的力学理解。我们在这里从理论上考察质乳囊泡的形状，假设它们由三个膜域组成：ail。高曲率的内域、中等曲率的外域和最外层的平坦域均处于无应力状态。我们假设薄膜的弯曲弹性和面内剪切弹性在这些区域是相同的。特别强调了膜曲率和面内剪切弹性对膜张力展开过程中囊泡力学的影响。通过弯曲应变能和面内剪切应变能的最小化计算出囊泡的形状，并通过特征膜颈识别出机械稳定的囊泡。在拉伸膜时，囊泡颈相对突然消失，导致膜形状由弯曲的凹痕组成。虽然囊泡的静息形状主要受膜自发曲率的影响，但当囊泡受到拉伸和展开时，膜剪切弹性（在红细胞膜中记录的一系列值）起着重要作用。展开囊泡所需的膜张力对其形状是敏感的，特别是当囊泡完全展开并接近相对平坦的形状时。
Highly curved cell membrane structures, such as plasmaleinmal vesicles (coveolae) and clathrin-coated pits, facilitate many cell,functions, including the clustering of membrane receptors and transport of specific extracellular macromolecules by endothelial cells. These structures are subject to large mechanical deformations when the plasma membrane is stretched and subject to a change of its curvature. To enhance our understanding of plasmaleinmal vesicles we need to improve the understanding of the mechanics in regions of high membrane curvatures. We examine here, theoretically, the shapes of plasmalemmal vesicles assuming that they consist of three membrane domains: ail. inner domain with high curvature, an outer domain with moderate curvature, and an outermost flat domain, all in the unstressed state. We assume the membrane properties are the same in these domains with membrane bending elasticity as well as in-plane shear elasticity. Special emphasis is placed on the effects of membrane curvature and in-plane shear elasticity on the mechanics of vesicle during unfolding by application of membrane tension. The vesicle shapes were computed by minimization of bending and in-plane shear strain energy Mechanically stable vesicles were identified with characteristic membrane necks. Upon stretch of the membrane, the vesicle necks disappeared relatively abruptly leading to membrane shapes that consist of curved indentations. While the resting shape of vesicles is predominantly affected by the membrane spontaneous curvatures, the membrane shear elasticity (for a range of values recorded in the red cell membrane) makes a significant contribution as the vesicle is subject to stretch and unfolding. The membrane tension required to unfold the vesicle is sensitive with respect to its shape, especially as the vesicle becomes fully unfolded and approaches a relative flat shape.