Membrane topology and function of Der3/Hrd1p as a ubiquitin-protein ligase (E3) involved in endoplasmic reticulum degradation
Membrane topology and function of Der3/Hrd1p as a ubiquitin-protein ligase (E3) involved in endoplasmic reticulum degradation
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DOI：
10.1074/jbc.m008608200
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发表时间：
2001-04-06
影响因子：
4.8
通讯作者：
Wolf, DH
中科院分区：
文献类型：
--
作者：
Deak, PM;Wolf, DH
内质网包含蛋白质质量控制系统，其发现错误折叠或未组装的分泌蛋白并使它们在胞质溶胶中降解，这需要将相应的蛋白质从内质网通过Sec 61转运子逆行转运回胞质溶胶。此外，一个完全胜任的泛素化机制和26 S蛋白酶体是必要的逆转位和降解。内质网的突变和错误折叠的蛋白质的泛素化主要依赖于泛素结合酶Ubc 7 p。此外，降解需要内质网的几种新的膜组分。在这里，我们提出了拓扑结构的先前发现的RING-MS指蛋白Der 3/Hrd 1 p，内质网膜的新组件之一。蛋白质跨越膜六次。含有RING指结构域的氨基末端和羧基末端面向细胞质。总之，RING指依赖性泛素化的错误折叠的羧肽酶yscY在体内，以及Der 3/Hrd 1 p本身在体外和RING指依赖性结合的Ubc 7 p，揭示Der 3/Hrd 1 p作为泛素蛋白连接酶（E3）的内质网相关的蛋白质降解过程。
The endoplasmic reticulum contains a protein quality control system that discovers malfolded or unassembled secretory proteins and subjects them to degradation in the cytosol, This requires retrograde transport of the respective proteins from the endoplasmic reticulum back to the cytosol via the Sec61 translocon. In addition, a fully competent ubiquitination machinery and the 26 S proteasome are necessary for retrotranslocation and degradation. Ubiquitination of mutated and malfolded proteins of the endoplasmic reticulum is dependent mainly on the ubiquitin conjugating enzyme Ubc7p. In addition, several new membrane components of the endoplasmic reticulum are required for degradation. Here we present the topology of the previously discovered RING-MS finger protein Der3/Hrd1p, one of the new components of the endoplasmic reticulum membrane. The protein spans the membrane six times. The amino terminus and the carboxyl terminus containing the RING finger domain face the cytoplasm. Altogether, RING finger-dependent ubiquitination of malfolded carboxypeptidase yscY in vivo, as well as of Der3/Hrd1p itself in vitro and RING finger dependent binding of Ubc7p, uncovers Der3/Hrd1p as the ubiquitin-protein ligase (E3) of the endoplasmic reticulum-associated protein degradation process.