Erv25p, a component of COPII-coated vesicles, forms a complex with Emp24p that is required for efficient endoplasmic reticulum to Golgi transport
Erv25p, a component of COPII-coated vesicles, forms a complex with Emp24p that is required for efficient endoplasmic reticulum to Golgi transport
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DOI：
10.1074/jbc.271.43.26939
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发表时间：
1996-10-25
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
COPII包被的内质网(ER)来源的运输小泡含有一组不同的膜结合多肽。我们已经获得了在纯化的囊泡上发现的多肽成分的NH2末端氨基酸序列，并在本报告中研究了24 kDa和25 kDa的物种。24 kDa的蛋白与Emp24p相同，Emp24p是一种I型跨膜蛋白，需要将分泌蛋白的子集从内质网运输到高尔基复合体(Schimmoller，F.，Singer-Kruger，B.，Schroder，S.，Kruger，U，Barlowe，C.和Riezman，H.(1995)EMBO J，14,1329-1339)。Erv25p(25 kDa的内质网泡囊蛋白)与酿酒酵母XIII染色体上的开放阅读框相对应，Erv25p与Emp24p具有完全相同的序列，但两种蛋白在功能上不能互换。针对Erv25p的抗体揭示，Emp24p和Erv25p的稳定性相互依赖，形成的蛋白质复合体可以在化学交联后分离出来。缺乏Erv25p(Erv25 Delta)的酵母菌株是活的，在将分泌蛋白从内质网运输到高尔基复合体的过程中表现出与emp24 Delta菌株相同的选择性缺陷。测量内质网膜泡形成的无细胞分析表明，当COPII包被的萌发重组时，Erv25p和Emp24p平等地掺入内质网衍生的囊泡中。由erv25 Delta株、emp24 Delta株和双erv25 Delta emp24 Delta株形成的囊泡是在野生型水平上进行的；然而，将Erv25p或Emp24p蛋白掺入COPII包被的囊泡需要表达这两个亚基，本文讨论了Erv25p-Emp24p复合体在内质网和高尔基体之间运输的潜在模型。
COPII-coated endoplasmic reticulum (ER)-derived transport vesicles contain a distinct set of membrane-bound polypeptides. We have obtained the NH2-terminal amino acid sequence of polypeptide constituents found on purified vesicles and in this report investigate the 24- and 25-kDa species. The 24-kDa protein is identical to Emp24p, a type I transmembrane protein that is required for transport of a subset of secretory proteins from the ER to the Golgi complex (Schimmoller, F., Singer-Kruger, B., Schroder, S., Kruger, U., Barlowe, C., and Riezman, H. (1995) EMBO J, 14, 1329-1339). The 25-kDa protein, termed Erv25p (ER vesicle protein of 25 kDa), corresponds to an open reading frame found on chromosome XIII of Saccharomyces cerevisiae, Erv25p shares overall sequence identity with Emp24p, but the two proteins are not functionally interchangeable. Antibodies directed against Erv25p reveal that Emp24p and Erv25p depend on each other for stability and form a protein complex that can be isolated after chemical cross-linking. Yeast strains lacking Erv25p (erv25 Delta) are viable and display the same selective defect in transport of secretory proteins from the ER to Golgi complex as an emp24 Delta strain. A cell-free assay that measures vesicle formation from ER membranes demonstrates that Erv25p and Emp24p are incorporated equally into ER-derived vesicles when COPII-coated budding is reconstituted. Vesicle formation from an erv25 Delta strain, an emp24 Delta strain and a double erv25 Delta emp24 Delta strain proceed at wild-type levels; however, incorporation of the Erv25p or the Emp24p protein into COPII-coated vesicles requires expression of both subunits, A potential model for transport of the Erv25p-Emp24p complex between the ER and Golgi compartments is discussed.