Immature granules are not major sites for segregation of constitutively secreted granule content proteins in NIT-1 insulinoma cells.
Immature granules are not major sites for segregation of constitutively secreted granule content proteins in NIT-1 insulinoma cells.
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未成熟颗粒不是 NIT-1 胰岛素瘤细胞中组成型分泌的颗粒内容蛋白分离的主要位点。
DOI：
10.1006/bbrc.2001.5889
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Jin,Y
中科院分区：
文献类型：
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作者：
Rindler,MJ;Colomer,V;Jin,Y
不成熟分泌颗粒（ISG）是内分泌细胞中通过不受调节的途径分泌的蛋白质与储存在成熟分泌颗粒中的蛋白质分离的位点。为了确定ISG中是否发生显著的可溶性蛋白分选，在NIT-1细胞中分析了胰腺蛋白GP 2（GP 2-GPI-）和胎盘碱性磷酸酶（SEAP）的可溶性形式的分泌。通过免疫荧光显微镜观察，两种蛋白质都不定位于转染细胞中的SG。它们的分泌是不依赖于促分泌素的脉冲追踪放射性标记实验，即使在早期的追逐，而一个小的增加，淀粉酶的分泌，这是已知的进入ISG的，可以检测到。最后，在蔗糖梯度分级实验中，SEAP存在于轻密度级分中。我们的结论是，虽然一些蛋白质，如淀粉酶，有一个有限的内在能力进入ISG的，分离的蛋白质分泌通过组成性途径从SG内容蛋白主要发生在transGolgi网络。
Immature secretory granules (ISG's) are sites of segregation of proteins destined for secretion by unregulated pathways from those stored in mature secretory granules in endocrine cells. To determine whether significant soluble protein sorting occurs in ISG's, the secretion of soluble versions of the pancreatic protein GP2 (GP2-GPI−) and placental alkaline phosphatase (SEAP) was analyzed in NIT-1 cells. By immunofluorescence microscopy, neither protein localized to SG's in transfected cells. Their secretion was secretagogue-independent in pulse-chase radiolabeling experiments even at early times of chase, while a small increase in the secretion of amylase, which is known to enter ISG's, could be detected. Finally, in sucrose gradient fractionation experiments, SEAP was present in light density fractions. We conclude that while some proteins, such as amylase, have a limited intrinsic capacity to enter ISG's, the segregation of proteins secreted via the constitutive pathway from SG content proteins occurs primarily in the trans Golgi network.