Dissection of COPI and Arf1 dynamics in vivo and role in Golgi membrane transport
Dissection of COPI and Arf1 dynamics in vivo and role in Golgi membrane transport
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DOI：
10.1038/417187a
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发表时间：
2002-05-09
期刊：
影响因子：
64.8
通讯作者：
Lippincott-Schwartz, J
中科院分区：
文献类型：
--
作者：
Presley, JF;Ward, TH;Lippincott-Schwartz, J
与膜可逆结合的胞质外壳蛋白在分泌途径中的膜运输中具有核心功能（1,2）。一个被充分研究的例子是COPI或涂层，这是一种七聚体蛋白复合物，通过gtp结合蛋白Arf1被招募到膜上。组装成一个电子致密的外壳，然后帮助出芽膜在内质网和高尔基体之间运输。本文通过分析荧光标记的涂层和Arf1在活细胞高尔基膜上的分布和寿命，提出并验证了涂层和Arf1活性的简单模型。我们发现活化的Arf1将涂层带到膜上。然而，一旦与膜结合，Arf1和coatomer有不同的停留时间：在Arf1- gtp被水解解离后，coatomer仍留在膜上。快速的膜结合和分离是随机发生的，即使没有囊泡出芽。我们认为涂层和Arf1的这种持续活性产生了动力学稳定的膜结构域，这些结构域与含有copi的转运中间体的形成有关。Arf1/coatomer的这一作用可能为研究细胞内其他被膜蛋白系统的行为提供一个模型。
Cytosolic coat proteins that bind reversibly to membranes have a central function in membrane transport within the secretory pathway(1,2). One well-studied example is COPI or coatomer, a heptameric protein complex that is recruited to membranes by the GTP-binding protein Arf1. Assembly into an electron-dense coat then helps in budding off membrane to be transported between the endoplasmic reticulum (ER) and Golgi apparatus 2. Here we propose and corroborate a simple model for coatomer and Arf1 activity based on results analysing the distribution and lifetime of fluorescently labelled coatomer and Arf1 on Golgi membranes of living cells. We find that activated Arf1 brings coatomer to membranes. However, once associated with membranes, Arf1 and coatomer have different residence times: coatomer remains on membranes after Arf1-GTP has been hydrolysed and dissociated. Rapid membrane binding and dissociation of coatomer and Arf1 occur stochastically, even without vesicle budding. We propose that this continuous activity of coatomer and Arf1 generates kinetically stable membrane domains that are connected to the formation of COPI-containing transport intermediates. This role for Arf1/coatomer might provide a model for investigating the behaviour of other coat protein systems within cells.