Kumar N, Blumenthal R, Henkart M, Weinstein J N, Klausner R D
J Biol Chem. 1982 Dec 25;257(24):15137-44.
Insertion of tubulin into the bilayer of dipalmitoyl phosphatidylcholine vesicles at the phase transition results in the formation of stable vesicle-tubulin complexes (Klausner, R. D., Kumar, N., Weinstein, J. N., Blumenthal, R., and Flavin, M. (1981) J. Biol. Chem. 256, 5879-5885). These complexes aggregated when maintained below phase transition for 10-20 min. Addition of millimolar concentrations of Ca2+, Mn2+, Zn2+, and Co2+, but not Mg2+, caused the vesicle-tubulin complexes to fuse into larger structures as shown by (a) electron microscopy, (b) increased trapped volume, and (c) changes ion resonance energy transfer between two fluorescent lipid probes incorporated into the same vesicle. There was no loss of internal aqueous contents from the vesicle-tubulin complexes during Ca2+-induced fusion. Anti-tubulin drugs had no effect on the aggregation or fusion, and vesicle-bound tubulin did not associate with microtubules when tubulin was assembled in vitro. Trypsin-treated vesicle-tubulin complexes were incapable of supporting Ca2+-induced fusion. This system provides a model for Ca2+-induced and protein-mediated nonleaky fusion of uncharged lipid bilayers.
在相变时将微管蛋白插入二棕榈酰磷脂酰胆碱囊泡的双层中会导致形成稳定的囊泡 - 微管蛋白复合物（克劳斯纳，R.D.，库马尔，N.，温斯坦，J.N.，布卢门撒尔，R.，和弗莱文，M.（1981年）《生物化学杂志》256，5879 - 5885）。当在低于相变温度下维持10 - 20分钟时，这些复合物会聚集。加入毫摩尔浓度的Ca2 +、Mn2 +、Zn2 +和Co2 +（但不是Mg2 +）会导致囊泡 - 微管蛋白复合物融合成更大的结构，这通过以下方式得以证明：（a）电子显微镜观察，（b）捕获体积增加，以及（c）掺入同一囊泡中的两种荧光脂质探针之间的离子共振能量转移变化。在Ca2 +诱导的融合过程中，囊泡 - 微管蛋白复合物内部的水性内容物没有损失。抗微管蛋白药物对聚集或融合没有影响，并且当微管蛋白在体外组装时，与囊泡结合的微管蛋白不会与微管相关联。经胰蛋白酶处理的囊泡 - 微管蛋白复合物无法支持Ca2 +诱导的融合。该系统为Ca2 +诱导的和蛋白质介导的无电荷脂质双层的非渗漏融合提供了一个模型。
