Plasma membrane damage and rupture occurs frequently in cells, and holes must be sealed rapidly to ensure homeostasis and cell survival. The membrane repair machinery is known to involve recruitment of curvature-inducing annexin proteins, but the connection between membrane remodeling and hole closure is poorly described. The induction of curvature by repair proteins leads to the possible formation of a membrane neck around the hole as a key intermediate structure before sealing. We formulate a theoretical model of equilibrium neck shapes to examine the potential connection to a repair mechanism. Using variational calculus, the shape equations for the membrane near a hole are formulated and solved numerically. The system is described under a condition of fixed area, and a shooting approach is applied to fulfill the boundary conditions at the free membrane edge. A state diagram of neck shapes is produced describing the variation in neck morphology with respect to the membrane area. Two distinct types of necks are predicted, one with conformations curved beyond π existing at positive excess area, whereas flat neck conformations (curved below π) have negative excess area. The results indicate that in cells, the supply of additional membrane area and a change in edge tension is linked to the formation of narrow and curved necks. Such necks may be susceptible to passive or actively induced membrane fission as a possible mechanism for hole sealing during membrane repair in cells.

中文翻译：

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质膜修复过程中孔周围膜颈的形状


细胞中经常发生质膜损伤和破裂，必须迅速密封孔洞以确保体内平衡和细胞存活。众所周知，膜修复机制涉及招募弯曲诱导的膜联蛋白，但膜重塑和孔闭合之间的联系却很少被描述。修复蛋白诱导的曲率导致孔周围可能形成膜颈，作为密封之前的关键中间结构。我们制定了平衡颈部形状的理论模型来检查与修复机制的潜在联系。使用变分法，对孔附近的膜的形状方程进行公式化并进行数值求解。该系统在固定面积的条件下进行描述，并采用射击方法来满足自由膜边缘的边界条件。生成颈部形状的状态图，描述颈部形态相对于膜面积的变化。预测了两种不同类型的颈部，一种是在正过剩区域存在弯曲超过 π 的构象，而平颈构象（弯曲低于 π）具有负过剩区域。结果表明，在细胞中，额外膜面积的供应和边缘张力的变化与狭窄和弯曲颈部的形成有关。这种颈部可能容易受到被动或主动诱导的膜裂变的影响，作为细胞膜修复过程中孔密封的可能机制。