In yeast the export of small glycopeptides from the endoplasmic reticulum into the cytosol is not affected by the structure of their oligosaccharide chains.
In yeast the export of small glycopeptides from the endoplasmic reticulum into the cytosol is not affected by the structure of their oligosaccharide chains.
复制标题
在酵母中，小糖肽从内质网输出到细胞质中不受其寡糖链结构的影响。
DOI：
10.1093/glycob/10.1.51
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发表时间：
2000
期刊：
影响因子：
4.3
通讯作者：
Lennarz,WJ
中科院分区：
文献类型：
--
作者：
Suzuki,T;Lennarz,WJ
一种与内质网(ER)相关的“质量控制”系统可以区分错误折叠的蛋白质和正确折叠的蛋白质，存在于包括酵母在内的各种真核细胞中。最近的研究表明，在内质网管腔内非糖基化的错误折叠蛋白被转运出内质网，被一种可溶性多肽：N-糖基酶(PNGase)去糖基化，并在蛋白酶体的作用下降解。研究还表明，小的N-糖基化肽的命运类似于错误折叠的蛋白质，即内质网管腔内的糖基化，内质网外的转运，以及胞浆中的去N-糖基化。这些糖肽逆行转运和去N-糖基化的过程已经在哺乳动物细胞中观察到，在酵母细胞中也是如此。然而，人们对糖肽从内质网到胞浆的运动机制知之甚少。本文报道了一种简单的纸层析和电泳法测定N-糖基化/去-N-糖基化的方法，该方法以可糖基化的~3H标记三肽为底物。通过这种方法，我们证实了去N-糖基化多肽在胞浆中的定位，这支持了去N-糖基化发生在糖肽从内质网的管腔输出到胞浆之后的观点。此外，我们发现糖肽上低聚糖链结构的变化并不会导致糖肽输出的差异。这一发现表明，小糖肽的输出机制可能不同于错误折叠(糖蛋白)的机制。
A “quality control” system associated with the endoplasmic reticulum (ER) that discriminates between misfolded proteins and correctly folded proteins is present in a variety of eukaryotic cells, including yeast. Recently, it has been shown that misfolded proteins that areN-glycosylated in the lumen of the ER are transported out of the ER, de-N-glycosylated by a soluble peptide:N-glycanase (PNGase) and degraded by action of the proteasome. It also has been shown that smallN-glycosylatable peptides follow a fate similar to that of misfolded proteins, i.e., glycosylation in the lumen of the ER, transport out of the ER, and de-N-glycosylation in the cytosol. These processes of retrograde glycopeptide transport and de-N-glycosylation have been observed in mammalian cells, as well as in yeast cells. However, little is known about the mechanism involved in the movement of glycopeptides from the ER to the cytosol. Here we report a simple method for assayingN-glycosylation/de-N-glycosylation by simple paper chromatographic and electrophoretic techniques using anN-glycosylatable3H-labeled tripeptide as a substrate. With this method, we confirmed the cytosolic localization of the de-N-glycosylated peptide, which supports the idea that de-N-glycosylation occurs after the export of the glycopeptide from the lumen of the ER to the cytosol. Further, we found that the variations in the structure of the oligosaccharide chain on the glycopeptide did not cause differences in the export of the glycopeptide. This finding suggests that the mechanism for the export of small glycopeptides may differ from that of misfolded (glyco)proteins.