Endomembrane trafficking of Ras: The CAAX motif targets proteins to the ER and Golgi
Endomembrane trafficking of Ras: The CAAX motif targets proteins to the ER and Golgi
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DOI：
10.1016/s0092-8674(00)80607-8
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发表时间：
1999-07-09
期刊：
影响因子：
64.5
通讯作者：
Philips, MR
中科院分区：
文献类型：
--
作者：
Choy, E;Chiu, VK;Philips, MR
我们发现Nras在质膜（PM）之前短暂地定位在高尔基体中。此外，绿色荧光蛋白（GFP）标记的Nras照亮了运动的高尔基囊泡，长时间的BFA处理阻断了PM的表达。GFP-Hras与GFP-Nras共定位，但GFP-Kras4B显示较少的高尔基体荧光，无囊泡荧光。虽然PM表达需要二级膜靶向信号，但CAAX基元本身就足以将蛋白质靶向到膜上，在膜上进行甲基化，这是有效的膜结合所必需的修饰。因此，烯丙基化CAAX蛋白不直接与PM结合，而是与内膜结合，随后被转运到PM，这一过程需要一个二级靶向基序。
We show that Nras is transiently localized in the Golgi prior to the plasma membrane (PM). Moreover, green fluorescent protein (GFP)-tagged Nras illuminated motile, peri-Golgi vesicles, and prolonged BFA treatment blocked PM expression. GFP-Hras colocalized with GFP-Nras, but GFP-Kras4B revealed less Golgi and no vesicular fluorescence. Whereas a secondary membrane targeting signal was required for PM expression, the CAAX motif alone was necessary and sufficient to target proteins to the endomembrane where they were methylated, a modification required for efficient membrane association. Thus, prenylated CAAX proteins do not associate directly with the PM but instead associate with the endomembrane and are subsequently transported to the PM, a process that requires a secondary targeting motif.