Glycolipid-anchored proteins in neuroblastoma cells form detergent-resistant complexes without caveolin.
Glycolipid-anchored proteins in neuroblastoma cells form detergent-resistant complexes without caveolin.
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DOI：
10.1083/jcb.129.3.619
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发表时间：
1995-05
期刊：
影响因子：
--
通讯作者：
Harris DA
中科院分区：
文献类型：
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作者：
Gorodinsky A;Harris DA
多年来已知糖基-磷脂酰肌醇（GPI）锚定蛋白与许多跨膜蛋白相反，在4 ℃下不溶于非离子去污剂如Triton X-100.最近，有人提出，这种行为反映了GPI连接的蛋白质掺入到大的聚集体中，这些聚集体富含鞘脂和胆固醇，以及胞质信号分子，如异源三聚体G蛋白和src家族酪氨酸激酶。有人认为，这些脂质-蛋白质复合物来源于小窝，即内皮细胞、平滑肌和肺中丰富的质膜的非网格蛋白包被的内陷。Caveolin是一种被提出的Caveolae的外壳蛋白，被认为是形成复合物所必需的。为了进一步研究去污剂抗性复合物和小窝之间的关系，我们已经表征了N2 a神经母细胞瘤细胞裂解物中GPI锚定蛋白的行为，所述细胞缺乏形态学上可识别的小窝，并且不表达小窝蛋白（Shyng，S. L.，J. E. Heuser和D. A.哈里斯1994. 125：1239-1250）。我们在这里报告说，从N2 a细胞制备的复合物显示大尺寸和低浮力密度的特点，从富含小窝的来源分离的复合物，并含有相同的主要成分，包括多个GPI锚定蛋白，α和β亚基的异源三聚体G蛋白，和酪氨酸激酶fyn和yes。我们的研究结果强烈认为，洗涤剂抗性复合物是不等同于小窝在所有类型的细胞，并在神经元细胞小窝蛋白是不是必不可少的这些复合物的完整性。
It has been known for a number of years that glycosyl- phosphatidylinositol (GPI)-anchored proteins, in contrast to many transmembrane proteins, are insoluble at 4 degrees C in nonionic detergents such as Triton X-100. Recently, it has been proposed that this behavior reflects the incorporation of GPI-linked proteins into large aggregates that are rich in sphingolipids and cholesterol, as well as in cytoplasmic signaling molecules such as heterotrimeric G proteins and src-family tyrosine kinases. It has been suggested that these lipid-protein complexes are derived from caveolae, non-clathrin- coated invaginations of the plasmalemma that are abundant in endothelial cells, smooth muscle, and lung. Caveolin, a proposed coat protein of caveolae, has been hypothesized to be essential for formation of the complexes. To further investigate the relationship between the detergent-resistant complexes and caveolae, we have characterized the behavior of GPI-anchored proteins in lysates of N2a neuroblastoma cells, which lack morphologically identifiable caveolae, and which do not express caveolin (Shyng, S.-L., J. E. Heuser, and D. A. Harris. 1994. J. Cell Biol. 125:1239-1250). We report here that the complexes prepared from N2a cells display the large size and low buoyant density characteristic of complexes isolated from sources that are rich in caveolae, and contain the same major constituents, including multiple GPI-anchored proteins, alpha and beta subunits of heterotrimeric G proteins, and the tyrosine kinases fyn and yes. Our results argue strongly that detergent-resistant complexes are not equivalent to caveolae in all cell types, and that in neuronal cells caveolin is not essential for the integrity of these complexes.