The subcellular localization of Arf family proteins is generally thought to be determined by their corresponding guanine nucleotide exchange factors. By promoting GTP binding, guanine nucleotide exchange factors induce conformational changes of Arf proteins exposing their N-terminal amphipathic helices, which then insert into the membranes to stabilize the membrane association process. Here, we found that the N-terminal amphipathic motifs of the Golgi-localized Arf family protein, Arfrp1, and the endosome- and plasma membrane–localized Arf family protein, Arl14, play critical roles in spatial determination. Exchanging the amphipathic helix motifs between these two Arf proteins causes the switch of their localizations. Moreover, the amphipathic helices of Arfrp1 and Arl14 are sufficient for cytosolic proteins to be localized into a specific cellular compartment. The spatial determination mediated by the Arfrp1 helix requires its binding partner Sys1. In addition, the residues that are required for the acetylation of the Arfrp1 helix and the myristoylation of the Arl14 helix are important for the specific subcellular localization. Interestingly, Arfrp1 and Arl14 are recruited to their specific cellular compartments independent of GTP binding. Our results demonstrate that the amphipathic motifs of Arfrp1 and Arl14 are sufficient for determining specific subcellular localizations in a GTP-independent manner, suggesting that the membrane association and activation of some Arf proteins are uncoupled.

中文翻译：

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Arfrp1 和 Arl14 的两亲性螺旋足以确定亚细胞定位。


通常认为Arf家族蛋白的亚细胞定位是由其相应的鸟嘌呤核苷酸交换因子决定的。通过促进 GTP 结合，鸟嘌呤核苷酸交换因子诱导 Arf 蛋白的构象变化，暴露其 N 末端两亲性螺旋，然后插入膜中以稳定膜缔合过程。在这里，我们发现高尔基体定位的 Arf 家族蛋白 Arfrp1 以及内体和质膜定位的 Arf 家族蛋白 Arl14 的 N 端两亲基序在空间决定中发挥着关键作用。这两种 Arf 蛋白之间交换两亲性螺旋基序会导致它们定位的转换。此外，Arfrp1 和 Arl14 的两亲性螺旋足以将胞质蛋白定位到特定的细胞区室中。 Arfrp1 螺旋介导的空间决定需要其结合伙伴 Sys1。此外，Arfrp1 螺旋乙酰化和 Arl14 螺旋肉豆蔻酰化所需的残基对于特定的亚细胞定位非常重要。有趣的是，Arfrp1 和 Arl14 被招募到其特定的细胞区室中，与 GTP 结合无关。我们的结果表明，Arfrp1 和 Arl14 的两亲基序足以以不依赖 GTP 的方式确定特定的亚细胞定位，这表明一些 Arf 蛋白的膜关联和激活是解偶联的。