IDENTIFICATION OF A SECRETORY GRANULE-BINDING PROTEIN AS CALDESMON
IDENTIFICATION OF A SECRETORY GRANULE-BINDING PROTEIN AS CALDESMON
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DOI：
10.1038/319068a0
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发表时间：
1986-01-02
期刊：
影响因子：
64.8
通讯作者：
NORMAN, KM
中科院分区：
文献类型：
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作者：
BURGOYNE, RD;CHEEK, TR;NORMAN, KM
刺激肾上腺嗜铬细胞导致细胞内游离钙浓度升高1 - 3，通过胞吐作用启动儿茶酚胺分泌4，5。了解胞吐作用的分子基础需要了解钙的作用部位。钙调素的作用与嗜铬细胞的分泌有关6，7，并且孤立的颗粒膜以钙依赖的方式结合钙调素8和一系列胞质蛋白9 - 12。在这里，我们证明了一个相对分子质量（Mr）为70，000（70 K）的胞质颗粒结合蛋白是钙调素调节的肌动蛋白结合蛋白caldesmon的一种形式，首先从平滑肌中分离出来13。细胞质凝胶组装从肾上腺髓质提取物在没有Ca 2+的情况下含有肌动蛋白和70 K蛋白。这两种蛋白质与细胞质凝胶的协会被抑制由微摩尔浓度的Ca 2+。此外，我们已经证明70 K蛋白定位于嗜铬细胞的外周。这些结果与70 K蛋白（caldesmon）在分泌过程中调节细胞周边肌动蛋白丝组织的观点一致。
Stimulation of adrenal chromaffin cells results in a rise in the concentration of intracellular free calcium1–3which initiates catecholamine secretion by exocytosis4,5. An understanding of the molecular basis of exocytosis will require knowledge of the sites of action of calcium. A role for calmodulin has been implicated in secretion from chromaffin cells6,7, and isolated granule membranes bind both calmodulin8and a series of cytosolic proteins9–12in a calcium-dependent fashion. Here, we demonstrate that one of the cytosolic granule-binding proteins with a relative molecular mass (Mr) of 70,000 (70K) is a form of the calmodulin-regulated actin-binding protein caldesmon, first isolated from smooth muscle13. Cytoplasmic gels assembled from an adrenal medullary extract in the absence of Ca2+contained actin and the 70K protein. The association of both of these proteins with the cytoplasmic gel was inhibited by a micromolar concentration of Ca2+. In addition, we have demonstrated that the 70K protein is localized at the periphery of chromaffin cells. These results are consistent with the notion that 70K protein (caldesmon) has a role in regulating the organization of actin filaments of the cell periphery during the secretory process.