Distinct roles for the cytoplasmic tail sequences of Emp24p and Erv25p in transport between the endoplasmic reticulum and Golgi complex
Distinct roles for the cytoplasmic tail sequences of Emp24p and Erv25p in transport between the endoplasmic reticulum and Golgi complex
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DOI：
10.1074/jbc.m108113200
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发表时间：
2001-11-16
影响因子：
4.8
通讯作者：
Barlowe, C
中科院分区：
文献类型：
--
作者：
Belden, WJ;Barlowe, C
p24蛋白的异聚体复合物在分泌途径的早期区室之间循环，并且是高效蛋白质分选所需的。在这里，我们研究了两个p24蛋白，Emp 24 p和Erv 25 p，在指导他们的运动和亚细胞定位在酵母细胞质暴露的尾部序列的作用。对一系列缺失和嵌合Emp 24 p-Erv 25 p蛋白的研究表明，尾部序列赋予不同的功能特性，这些功能特性是部分冗余的，但不是完全可互换的。出口的Emp 24 p-Erv 25 p复合物从内质网（ER）不依赖于其他两个相关的p24蛋白，Erp 1和Erp 2 p。为了检查Emp 24 p和Erv 25 p尾序列与COPI和COPII外壳蛋白之间的相互作用，进行了固定化尾肽和外壳蛋白的结合实验。Emp 24 p和Erv 25 p尾部序列结合COPII外壳的Sec 13 p/Sec 31 p亚基（K-d类似于100 μ m），并且结合依赖于在两个尾部序列中发现的一对芳香族残基。COPI亚基也结合到这些Emp 24 p和Erv 25 p肽;然而，Erv 25 p尾序列，其中包含一个二赖氨酸基序，结合COPI更有效。这些结果表明，Emp 24 p和Erv 25 p细胞质序列都含有结合COPII外壳亚基并促进从ER输出的二芳香基序。Erv 25 p尾序列结合COPI并负责将该复合物返回ER。
Heteromeric complexes of p24 proteins cycle between early compartments of the secretory pathway and are required for efficient protein sorting. Here we investigated the role of cytoplasmically exposed tail sequences on two p24 proteins, Emp24p and Erv25p, in directing their movement and subcellular location in yeast. Studies on a series of deletion and chimeric Emp24p-Erv25p proteins indicated that the tail sequences impart distinct functional properties that were partially redundant but not entirely interchangeable. Export of an Emp24p-Erv25p complex from the endoplasmic reticulum (ER) did not depend on two other associated p24 proteins, Erp1 and Erp2p. To examine interactions between the Emp24p and Erv25p tail sequences with the COPI and COPII coat proteins, binding experiments with immobilized tail peptides and coat proteins were performed. The Emp24p and Erv25p tail sequences bound the Sec13p/Sec31p subunit of the COPII coat (K-d similar to 100 mum), and binding depended on a pair of aromatic residues found in both tail sequences. COPI subunits also bound to these Emp24p and Erv25p peptides; however, the Erv25p tail sequence, which contains a dilysine motif, bound COPI more efficiently. These results suggest that both the Emp24p and Erv25p cytoplasmic sequences contain a di-aromatic motif that binds subunits of the COPII coat and promotes export from the ER. The Erv25p tail sequence binds COPI and is responsible for returning this complex to the ER.