Retrograde transport from the yeast Golgi is mediated by two ARF GAP proteins with overlapping function
Retrograde transport from the yeast Golgi is mediated by two ARF GAP proteins with overlapping function
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DOI：
10.1093/emboj/18.3.555
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发表时间：
1999-02-01
期刊：
影响因子：
11.4
通讯作者：
Johnston, GC
中科院分区：
文献类型：
--
作者：
Poon, PP;Cassel, D;Johnston, GC
介导囊泡运输的 ARF 蛋白几乎没有或没有内在的 GTP 酶活性。它们的功能依赖于 GTP 酶激活蛋白 (GAP) 的作用。酿酒酵母 ARF 蛋白 Arf1 和 Arf2 的体外 GTP 酶活性受到酵母 Gcs1 蛋白的刺激，arf 和 gcs1 突变之间的体内遗传相互作用表明 Gcs1 参与囊泡运输。然而，Gcs1 蛋白是可有可无的，这表明存在额外的 ARF GAP 蛋白。我们发现，结构相关的蛋白质 Glo3（也是可有可无）也表现出 ARF GAP 活性。遗传和体外方法表明，Glo3 和 Gcs1 在囊泡运输的内质网 (ER)-高尔基体阶段具有重叠的基本功能。缺乏两个 ARF GAP 的突变细胞无法增殖，内质网大量积聚，并且内质网和高尔基体之间的蛋白质转运存在缺陷。 glo3 Delta 和 gcs1 Delta 单突变均与影响 COPI 成分的 sec21 突变相互作用，COPI 介导 ER-高尔基体穿梭内的囊泡运输，而编码在 ER-高尔基体内起作用的 v-SNARE 家族成员的 BET1、BOS1 和 SEC22 基因的剂量增加可减轻 glo3 Delta 突变的影响。体外测定表明，从高尔基体到 ER 的有效检索需要这两种蛋白质。这些发现表明 Glo3 和 Gcs1 ARF GAP 介导从高尔基体到内质网的逆行囊泡转运。
ARF proteins, which mediate vesicular transport, have little or no intrinsic GTPase activity. They rely on the actions of GTPase-activating proteins (GAPs) for their function. The in vitro GTPase activity of the Saccharomyces cerevisiae ARF proteins Arf1 and Arf2 is stimulated by the yeast Gcs1 protein, and in vivo genetic interactions between arf and gcs1 mutations implicate Gcs1 in vesicular transport. However, the Gcs1 protein is dispensable, indicating that additional ARF GAP proteins exist. We show that the structurally related protein Glo3, which is also dispensable, also exhibits ARF GAP activity, Genetic and in vitro approaches reveal that Glo3 and Gcs1 have an overlapping essential function at the endoplasmic reticulum (ER)-Golgi stage of vesicular transport. Mutant cells deficient for both ARF GAPs cannot proliferate, undergo a dramatic accumulation of ER and are defective for protein transport between ER and Golgi. The glo3 Delta and gcs1 Delta single mutations each interact with a sec21 mutation that affects a component of COPI, which mediates vesicular transport within the ER-Golgi shuttle, while increased dosage of the BET1, BOS1 and SEC22 genes encoding members of a v-SNARE family that functions within the ER-Golgi alleviates the effects of a glo3 Delta mutation, An in vitro assay indicates that efficient retrieval from the Golgi to the ER requires these two proteins. These findings suggest that Glo3 and Gcs1 ARF GAPs mediate retrograde vesicular transport from the Golgi to the ER.