N-myristoylation determines dual targeting of mammalian NADH-cytochrome b(5) reductase to ER and mitochondrial outer membranes by a mechanism of kinetic partitioning
N-myristoylation determines dual targeting of mammalian NADH-cytochrome b(5) reductase to ER and mitochondrial outer membranes by a mechanism of kinetic partitioning
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DOI：
10.1083/jcb.200407082
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发表时间：
2005-02-28
影响因子：
7.8
通讯作者：
Borgese, N
中科院分区：
文献类型：
--
作者：
Colombo, S;Longhi, R;Borgese, N
哺乳动物NADH-细胞色素B（5）还原酶（b5 R）是一种N-肉豆蔻酰化蛋白，其双重靶向ER和线粒体外膜。锚定到膜上不需要Winked肉豆蔻酸酯，因为靠近NH 2末端的一段疏水性氨基酸保证了蛋白质与磷脂双层的紧密相互作用。相反，由于非豆蔻酰化的突变体仅定位于ER，因此脂肪酸是b5 R靶向线粒体所必需的。在这里，我们研究了眨眼肉豆蔻酸酯影响b5 R靶向的机制。我们发现豆蔻酰化干扰新生链与信号识别颗粒的相互作用，使得一部分新生链从共翻译整合中逃逸到ER中，并且可以在转录后靶向线粒体外膜。因此，两个共翻译事件之间的竞争，信号识别颗粒的结合和N-豆蔻酰化修饰，决定了翻译的网站和本地化的b5 R。
Mammalian NADH-cytochrome b(5) reductase (b5R) is an N-myristoylated protein that is dually targeted to ER and mitochondrial outer membranes. The Winked myristate is not required for anchorage to membranes because a stretch of hydrophobic amino acids close to the NH2 terminus guarantees a tight interaction of the protein with the phospholipid bilayer. instead, the fatty acid is required for targeting of b5R to mitochondria because a nonmyristoylated mutant is exclusively localized to the ER. Here, we have investigated the mechanism by which Winked myristate affects b5R targeting. We find that myristoylation interferes with interaction of the nascent chain with signal recognition particle, so that a portion of the nascent chains escapes from cotranslational integration into the ER and can be post-translationally targeted to the mitochondrial outer membrane. Thus, competition between two cotranslational events, binding of signal recognition particle and modification by N-myristoylation, determines the site of translation and the localization of b5R.