STUDIES ON MEMBRANE-FUSION .3. ROLE OF CALCIUM-INDUCED PHASE-CHANGES
STUDIES ON MEMBRANE-FUSION .3. ROLE OF CALCIUM-INDUCED PHASE-CHANGES
复制标题
DOI：
10.1016/0005-2736(77)90275-9
复制
发表时间：
1977-01-01
期刊：
影响因子：
--
通讯作者：
LAZO, R
中科院分区：
文献类型：
--
作者：
PAPAHADJOPOULOS, D;VAIL, WJ;LAZO, R
通过多种技术研究磷脂酰丝氨酸囊泡与Ca ~（2+）和Mg ~（2+）的相互作用，以研究膜融合的机制。数据上的Ca 2+和Mg 2+对囊泡的渗透性，热致相变和形态确定的差示扫描量热法，X-射线衍射和冷冻断裂EM的影响。这些数据进行了讨论有关的信息Ca 2+结合，电荷中和，分子包装，囊泡聚集，相变，相分离和囊泡融合。在1.0-2.0 mM的Ca 2+浓度下，发生高度协同现象，其导致囊泡通透性增加、囊泡聚集和融合。在这些条件下，脂质双层的烃链经历从流体到结晶状态的相变。在融合过程中观察到的囊泡聚集本身不足以在没有伴随相变的情况下诱导融合。Mg 2+在2.0-5.0 mM的范围内诱导磷脂酰丝氨酸囊泡的聚集，但没有显著的融合，也没有相变。pH值、温度、Ca ~（2+）和Mg ~（2+）浓度的变化对囊泡融合的影响表明，二价金属诱导的等温相变是导致囊泡膜融合的关键事件。这种相变可能会引起一个短暂的不稳定的双层膜，变得容易融合域边界。
The interaction of phosphatidylserine vesicles with Ca2+ and Mg2+ was examined by several techniques to study the mechanism of membrane fusion. Data are presented on the effects of Ca2+ and Mg2+ on vesicle permeability, thermotropic phase transitions and morphology determined by differential scanning calorimetry, X-ray diffraction and freeze-fracture EM. These data are discussed in relation to information concerning Ca2+ binding, charge neutralization, molecular packing, vesicle aggregation, phase transitions, phase separations and vesicle fusion. At Ca2+ concentrations of 1.0-2.0 mM, a highly cooperative phenomenon occurs which results in increased vesicle permeability, aggregation and fusion of the vesicles. Under these conditions the hydrocarbon chains of the lipid bilayers undergo a phase change from a fluid to a crystalline state. The aggregation of vesicles that is observed during fusion is not sufficient in itself to induce fusion without a concomitant phase change. Mg2+ in the range of 2.0-5.0 mM induces aggregation of phosphatidylserine vesicles but no significant fusion nor a phase change. The effect of variations in pH, temperature, Ca2+ and Mg2+ concentration on the fusion of vesicles indicates that the key event leading to vesicle membrane fusion is the isothermic phase change induced by the bivalent metals. This phase change may induce a transient destabilization of the bilayer membranes that become susceptible to fusion at domain boundaries.