cis-Unsaturated fatty acids induce the fusion of chromaffin granules aggregated by synexin.
cis-Unsaturated fatty acids induce the fusion of chromaffin granules aggregated by synexin.
复制标题
DOI：
10.1083/jcb.91.1.247
复制
发表时间：
1981-10
影响因子：
7.8
通讯作者：
Creutz, C E
中科院分区：
文献类型：
--
作者：
Creutz, C E
当分离的染色质颗粒被突触蛋白（一种存在于染色质和其他分泌组织中的Ca2+结合蛋白）聚集，然后暴露于37℃的顺式不饱和脂肪酸中时，它们融合在一起形成大囊泡。通过相显微镜和电子显微镜以及颗粒悬浮液的浊度测量来监测融合过程。花生四烯酸是最有效的fusogen，而反式不饱和脂肪酸、饱和脂肪酸、洗涤剂和溶卵磷脂则没有活性。在融合过程中，颗粒中的一些肾上腺素被释放，但可溶性核心蛋白仍然被困在产生的囊泡中。这些囊泡膨胀到最大体积。虽然这种膨胀可以通过增加介质的渗透强度来抑制，但它似乎并不取决于颗粒膜的化学渗透特性，因为它不受ATP、质子离子载体或阴离子运输抑制剂的影响。这种体外融合的调节因子——Ca2+、联联蛋白和游离的顺式不饱和脂肪酸——可能存在于嗜铬细胞的细胞质中，当嗜铬细胞通过胞外作用刺激释放肾上腺素和颗粒蛋白时。因此，这种融合事件可能与发生在复合胞吐的染色质颗粒之间的融合事件相同。
When isolated chromaffin granules were aggregated by synexin (a Ca2+- binding protein present in chromaffin and other secretory tissues) and then exposed to cis-unsaturated fatty acids at 37 degrees C, they fused together to form large vesicles. The fusion was monitored by phase and electron microscopy and by turbidity measurements on the granule suspension. Arachidonic acid was the most effective fusogen, whereas trans-unsaturated fatty acids, saturated fatty acids, detergents or lysolecithin were inactive. During fusion some of the epinephrine of the granules was released but the soluble core proteins remained trapped in the resulting vesicles. These vesicles swelled to enclose the maximum volume. Although this swelling could be inhibited by increasing the osmotic strength of the medium, it did not appear to depend on the chemiosmotic properties of the granule membranes as it was not influenced by ATP, a proton ionophore, or an anion transport inhibitor. The regulators of this in vitro fusion--Ca2+, synexin, and free, cis-unsaturated fatty acids--may be present in the cytoplasm of the chromaffin cell when it is stimulated to release epinephrine and granule proteins by exocytosis. Therefore, this fusion event may be the same that occurs between chromaffin granules undergoing compound exocytosis.