Markin V S, Kozlov M M, Borovjagin V L
Gen Physiol Biophys. 1984 Oct;3(5):361-77.
Based on literary data, conditions necessary for membrane fusion are discussed. It is proposed that fusion mechanisms should be classified according to the primary act involving a change in the membrane structure. Two principal fusion mechanisms are identified: the stalk mechanism, starting with the appearance of a stalk between approaching membranes, and the adhesion mechanism which involves bilayer reorganization as a result of a tight junction of the membranes. The origin and evolution of the monolayer and bilayer stalks between membranes are analysed. Using the expression for the elastic energy of the stalk it was possible to find the value of the spontaneous curvature of its membrane, Ks, at which the existence of a stalk is in principle possible. It is shown that, within the framework of the stalk mechanism, there exists a possibility of either the formation of a stalk of a finite radius, or complete fusion. The Ks values have been determined at which one of the variants occur. The energy barrier of the hydrophobic interaction and the elastic energy barrier, which have to be overcome by the membranes to form the stalk are analysed. The theoretical analysis of the stalk formation mechanism is supported by experimental data. It has been shown by freeze-fracture electron microscopy that the addition of Ca+2, Mg+2, Mn+2 or Cd+2 to suspensions of egg phosphatidylcholine and cardiolipin (1:1 or 3:1) leads to the formation of numerous intramembrane particles (imp's) and crater-like (stalk) structures.
基于文献数据，讨论了膜融合所需的条件。提出应根据涉及膜结构变化的主要行为对融合机制进行分类。确定了两种主要的融合机制：茎干机制，始于接近的膜之间出现茎干；粘附机制，涉及由于膜的紧密连接导致的双层重组。分析了膜之间单层和双层茎干的起源和演化。利用茎干弹性能的表达式，有可能找到其膜的自发曲率值Ks，在该值下茎干原则上可能存在。结果表明，在茎干机制的框架内，存在形成有限半径茎干或完全融合的可能性。已经确定了出现其中一种变体时的Ks值。分析了膜形成茎干时必须克服的疏水相互作用能垒和弹性能垒。茎干形成机制的理论分析得到了实验数据的支持。冷冻断裂电子显微镜显示，向卵磷脂和心磷脂（1:1或3:1）悬浮液中添加Ca+2、Mg+2、Mn+2或Cd+2会导致形成大量膜内颗粒（imp's）和火山口状（茎干）结构。
