Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany.
Mol Biol Cell. 2010 Mar 1;21(5):691-703. doi: 10.1091/mbc.e09-08-0730. Epub 2010 Jan 13.
Because of similarity to their yeast orthologues, the two membrane proteins of the human endoplasmic reticulum (ER) Sec62 and Sec63 are expected to play a role in protein biogenesis in the ER. We characterized interactions between these two proteins as well as the putative interaction of Sec62 with ribosomes. These data provide further evidence for evolutionary conservation of Sec62/Sec63 interaction. In addition, they indicate that in the course of evolution Sec62 of vertebrates has gained an additional function, the ability to interact with the ribosomal tunnel exit and, therefore, to support cotranslational mechanisms such as protein transport into the ER. This view is supported by the observation that Sec62 is associated with ribosomes in human cells. Thus, the human Sec62/Sec63 complex and the human ER membrane protein ERj1 are similar in providing binding sites for BiP in the ER-lumen and binding sites for ribosomes in the cytosol. We propose that these two systems provide similar chaperone functions with respect to different precursor proteins.
由于与酵母直系同源物相似，人类内质网（ER）中的两种膜蛋白 Sec62 和 Sec63 有望在内质网中发挥蛋白质生物发生的作用。我们描述了这两种蛋白之间的相互作用以及 Sec62 与核糖体的假定相互作用。这些数据为 Sec62/Sec63 相互作用的进化保守性提供了进一步的证据。此外，它们表明在进化过程中，脊椎动物的 Sec62 获得了额外的功能，即与核糖体隧道出口相互作用的能力，从而支持共翻译机制，如将蛋白质运输到内质网。这一观点得到了以下观察结果的支持：Sec62 与人细胞中的核糖体相关。因此，人 Sec62/Sec63 复合物和人内质网膜蛋白 ERj1 在提供内质网腔中 BiP 的结合位点和细胞质中核糖体的结合位点方面是相似的。我们提出这两个系统对于不同的前体蛋白提供了类似的伴侣功能。
