Role of Sec61α in the regulated transfer of the ribosome-nascent chain complex from the signal recognition particle to the translocation channel
Role of Sec61α in the regulated transfer of the ribosome-nascent chain complex from the signal recognition particle to the translocation channel
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DOI：
10.1016/s0092-8674(00)80669-8
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发表时间：
2000-02-04
期刊：
影响因子：
64.5
通讯作者：
Gilmore, R
中科院分区：
文献类型：
--
作者：
Song, WQ;Raden, D;Gilmore, R
核糖体新生链复合物靶向内质网中的易位子是由信号识别颗粒 (SRP) 和 SRP 受体 (SR) 的协同作用介导的。用蛋白酶消化去核糖体的微粒体，以切断 SR α、SR β、TRAM 和 Sec61 复合物的细胞质结构域。我们表征了当 Sec61 α 或 SRP 因蛋白水解而失活时积累的蛋白质易位中间体。在缺乏功能性 Sec61 复合物的情况下，SRP54 从信号序列中的解离被阻断。使用 SR 蛋白脂质体的实验证实了膜结合后靶向中间体的组装。这些结果强烈表明，Sec61复合物在信号序列从SRP54解离的阶段调节SRP-SR复合物的GTP水解循环。
Targeting of ribosome-nascent chain complexes to the translocon in the endoplasmic reticulum is mediated by the concerted action of the signal recognition particle (SRP) and the SRP receptor (SR). Ribosome-stripped microsomes were digested with proteases to sever cytoplasmic domains of SR alpha, SR beta, TRAM, and the Sec61 complex. We characterized protein translocation intermediates that accumulate when Sec61 alpha or SRP is inactivated by proteolysis. In the absence of a functional Sec61 complex, dissociation of SRP54 from the signal sequence is blocked. Experiments using SR proteoliposomes confirmed the assembly of a membrane-bound posttargeting intermediate. These results strongly suggest that the Sec61 complex regulates the GTP hydrolysis cycle of the SRP-SR complex at the stage of signal sequence dissociation from SRP54.