Role of synexin in membrane fusion. Enhancement of calcium-dependent fusion of phospholipid vesicles.
Role of synexin in membrane fusion. Enhancement of calcium-dependent fusion of phospholipid vesicles.
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DOI：
10.1016/s0021-9258(19)69500-1
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发表时间：
1981-04
期刊：
影响因子：
--
通讯作者：
K. Hong;N. Düzgüneş;D. Papahadjopoulos
中科院分区：
文献类型：
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作者：
K. Hong;N. Düzgüneş;D. Papahadjopoulos
Synexin 是一种可溶性肾上腺髓质和肝脏蛋白，可引起分离的嗜铬颗粒的钙依赖性聚集，根据已公布的程序进行分离和纯化。检查了突触蛋白对膜融合动力学的影响。通过混合磷脂囊泡的含水内容物来测定膜融合。 Synexin 降低了磷脂酰丝氨酸的大单层囊泡以及磷脂酰丝氨酸与磷脂酰乙醇胺的混合物融合所需的 CA2+ 浓度阈值。 synexin 还大大提高了初始融合率。初始融合速率随着反应混合物中突触蛋白数量的增加而增加。在存在 1-2 mM Ca2+ 和 50 µM 磷脂的情况下，20 至 40 µg/ml 的 Synexin 可使融合率提高两个数量级。 Mg2+ 不支持 Synexin 诱导的融合。对于含有磷脂酰丝氨酸和磷脂酰胆碱混合物的囊泡，synexin 在 CA2+ 存在的情况下增强聚集，而不促进融合。 Synexin 可能在 Ca2+ 存在的情况下通过促进含有特定磷脂的膜融合而在胞吐作用中发挥作用。
Synexin, a soluble adrenal medullary and liver protein which causes calcium-dependent aggregation of isolated chromaffin granules, was isolated and purified according to published procedures. The effects of synexin on the kinetics of membrane fusion were examined. Membrane fusion was assayed by following the mixing of aqueous contents of phospholipid vesicles. Synexin lowers the threshold of CA2+ concentration required for fusion of large unilamellar vesicles of phosphatidylserine and a mixture of phosphatidylserine with phosphatidylethanolamine. synexin also increases drastically the initial rate of fusion. the initial rate of fusion increases with the quantity of synexin present in the reaction mixture. In the presence of 1-2 mM Ca2+ and 50 microM phospholipid, synexin at 20 to 40 micrograms/ml increases the rate of fusion by two orders of magnitude. Mg2+ does not support synexin-induced fusion. With vesicles containing a mixture of phosphatidylserine with phosphatidylcholine, synexin enhances aggregation in the presence of CA2+, without promoting fusion. Synexin may play a role in exocytosis by promoting fusion of membranes containing specific phospholipids in the presence of Ca2+.