Rab-GDI presents functional Rab9 to the intracellular transport machinery and contributes selectivity to Rab9 membrane recruitment.
Rab-GDI presents functional Rab9 to the intracellular transport machinery and contributes selectivity to Rab9 membrane recruitment.
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DOI：
10.1016/s0021-9258(17)40696-x
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发表时间：
1994-06
期刊：
影响因子：
--
通讯作者：
A. Dirac-Svejstrup;T. Soldati;A. D. Shapiro;S. Pfeffer
中科院分区：
文献类型：
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作者：
A. Dirac-Svejstrup;T. Soldati;A. D. Shapiro;S. Pfeffer
Rab蛋白存在于与Rab-GDP解离抑制剂（GDI）结合的胞质溶胶中。我们在这里证明，结合到GDI的Rab 9的胞质复合物代表Rab 9蛋白的功能池，其可用于从晚期内体运输到体外的transGolgi网络。GDI和Rab蛋白结合到GDI的免疫耗竭导致胞质溶胶活性的损失;纯Rab 9-GDI复合物的再添加完全恢复胞质溶胶活性。脱脂血清白蛋白可以增溶异戊二烯化Rab 9蛋白，但与Rab 9-GDI复合物不同，Rab 9-血清白蛋白复合物导致Rab 9蛋白不加选择的膜缔合。Rab 9通过血清白蛋白传递到膜是有功能的，但GDI增加Rab 9利用的效率，可能是因为它抑制Rab 9蛋白的错误启动。最后，GDI抑制蛋白质从晚期内体转运到transGolgi网络，可能是因为其抑制胞质Rab 9的膜募集的能力。这些实验表明，GDI有助于Rab 9膜募集的选择性，并将功能性Rab 9呈现给内体-高尔基体网络转运机制。
Rab proteins occur in the cytosol bound to Rab-GDP dissociation inhibitor (GDI). We demonstrate here that cytosolic complexes of Rab9 bound to GDI represent a functional pool of Rab9 protein that can be utilized for transport from late endosomes to the trans Golgi network in vitro. Immunodepletion of GDI and Rab proteins bound to GDI led to the loss of cytosol activity; readdition of pure Rab9-GDI complexes fully restored cytosol activity. Delipidated serum albumin could solubilize prenylated Rab9 protein, but unlike Rab9-GDI complexes, Rab9-serum albumin complexes led to indiscriminate membrane association of Rab9 protein. Rab9 delivered to membranes by serum albumin was functional, but GDI increased the efficiency of Rab9 utilization, presumably because it suppressed Rab9 protein mistargeting. Finally, GDI inhibited transport of proteins from late endosomes to the trans Golgi network, likely because of its capacity to inhibit the membrane recruitment of cytosolic Rab9. These experiments show that GDI contributes to the selectivity of Rab9 membrane recruitment and presents functional Rab9 to the endosome-trans Golgi network transport machinery.