Lyko F, Martoglio B, Jungnickel B, Rapoport T A, Dobberstein B
ZMBH, Universität Heidelberg, Germany.
J Biol Chem. 1995 Aug 25;270(34):19873-8. doi: 10.1074/jbc.270.34.19873.
Secretory proteins are synthesized with a signal sequence that is usually cleaved from the nascent protein during the translocation of the polypeptide chain into the lumen of the endoplasmic reticulum. To determine the fate of a cleaved signal sequence, we used a synchronized in vitro translocation system. We found that the cleaved signal peptide of preprolactin is further processed close to its COOH terminus. The resulting fragment accumulated in the microsomal fraction and with time was released into the cytosol. Signal sequence cleavage and processing could be reproduced with reconstituted vesicles containing Sec61, signal recognition particle receptor, and signal peptidase complex.
分泌蛋白在合成时带有一个信号序列，该信号序列通常在多肽链转运到内质网腔的过程中从新生蛋白质上被切割下来。为了确定被切割的信号序列的命运，我们使用了一个同步体外转运系统。我们发现，前催乳素被切割的信号肽在其COOH末端附近进一步加工。产生的片段积聚在微粒体部分，并随着时间的推移释放到细胞质中。信号序列的切割和加工可以用含有Sec61、信号识别颗粒受体和信号肽酶复合物的重组囊泡来重现。
