Shape transitions during clathrin-induced endocytosis
Shape transitions during clathrin-induced endocytosis
复制标题
DOI：
10.1103/physreve.94.062404
复制
发表时间：
2016-12-16
影响因子：
2.4
通讯作者：
Sain, Anirban
中科院分区：
文献类型：
--
作者：
Kumar, Gaurav;Sain, Anirban
内吞作用是细胞从细胞外环境接收大分子（即所谓的货物）的最常见运输机制之一。特别是，网格蛋白介导的内吞作用（CME）涉及细胞质蛋白网格蛋白，它诱导含有细胞外货物的网格蛋白包被的膜芽的形成和内化。几十年的实验工作表明，网格蛋白外壳的形态随着时间的推移而变化，并在膜芽上诱导其弯曲；但这一过程的能量学仍不清楚。Avinoam等人最近的实验[Science 348, 1369(2015)]报道了网格蛋白涂层的面积保持固定，但其曲率随着时间的推移而增加，并且涂层中的网格蛋白分子快速翻转。我们表明这些观察结果挑战了现有的涂层膜芽形成模型。我们分析了他们的数据，得出了与涂层底层晶格结构一致的某些特征。我们假设膜曲率抑制网格蛋白沉积，并提出了一个动力学模型来解释网格蛋白外壳的面积分布。我们还表明，他们的数据的形状演变的膜芽可以从简单的几何考虑近似理解。然而，控制这一过程动力学的涂层形成的能量学仍然是一个谜。
Endocytosis is among the most common transport mechanisms which cells employ to receive macromolecules, the so-called cargo, from its extra cellular environment. Clathrin-mediated endocytosis (CME), in particular, involves the cytoplasmic protein clathrin which induces formation and internalization of clathrin-coated membrane buds that contain extra-cellular cargo. Decades of experimental work have established that the morphology of the clathrin coat evolves with time and induces its curvature on the membrane bud; but energetics of the process remain unclear. Recent experiments by Avinoam et al. [Science 348, 1369 (2015)] reported that the area of the clathrin coat remains fixed while its curvature increases with time and also the clathrin molecules in the coat turn over rapidly. We show that these observations challenge existing models of coated membrane bud formation. We analyze their data to bring out certain features consistent with the underlying lattice structure of the coat. We hypothesize that membrane curvature inhibits clathrin deposition and propose a kinetic model that explains the area distribution of clathrin coats. We also show that their data on shape evolution of the coated membrane bud can be approximately understood from simple geometric considerations. However, the energetics of the coat formation which controls the kinetics of the process remains a puzzle.