胞吐
分泌物
膜联蛋白A2
膜联蛋白
生物
细胞生物学
嗜铬细胞
胞浆
膜联蛋白A5
细胞外
小泡
生物化学
膜
肾上腺髓质
细胞凋亡
儿茶酚胺
内分泌学
酶
作者
Ariane-Valérie Faure,Carole Migné,Ginnette Devilliers,Jesús Ayala-Sanmartín
标识
DOI:10.1006/excr.2002.5512
摘要
Annexin 2 is a Ca(2+)-dependent phospholipid-binding protein that is involved in secretion. Despite the fact that this protein does not have signals for its secretion, many reports have shown its presence in the extracellular milieu. Here we demonstrate that, upon stimulation of exocytosis in chromaffin cells, a fraction of annexin 2 is secreted into the culture medium. This release of annexin 2 is specific, correlated with catecholamine secretion, and independent of cell death. To explain the liberation of cytosolic annexin 2 into the medium, we propose and bring evidence for a mechanism of multiporic membrane disruption during membrane fusion. Prior, in cross-linking experiments, annexin 2 forms aggregates of high molecular weight, revealing its capacity to form networks. Second, immunoelectron microscopy studies of fused chromaffin granules revealed the presence of annexin 2 and membrane proteins inside the fused vesicles, as would be predicted by the multiporic hypotheses. These data suggest that annexin 2 "secretion" in chromaffin cells is the consequence of membrane disruption during exocytosis. The role of annexin 2 in exocytosis is also discussed.
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