Römisch K, Schekman R
Department of Molecular and Cell Biology, University of California, Berkeley 94720.
Proc Natl Acad Sci U S A. 1992 Aug 1;89(15):7227-31. doi: 10.1073/pnas.89.15.7227.
Protein and peptide export from the Saccharomyces cerevisiae endoplasmic reticulum was examined in vitro using the secretory protein pro-alpha-factor and a synthetic tripeptide containing the acceptor site for N-linked glycosylation as substrates. The release of both glycosylated pro-alpha-factor and glycotripeptide from the endoplasmic reticulum was dependent on cytosol, temperature, and ATP. Antibodies against two proteins essential for the formation of transport vesicles, Sec23p and p105, inhibited glyco-pro-alpha-factor exit from the endoplasmic reticulum but did not affect the release of the glycosylated tripeptide. Furthermore, in contrast to pro-alpha-factor, the exported glycopeptide was not associated with a membrane fraction and did not acquire Golgi-specific alpha(1-6)-linked mannose residues. We conclude that the glycosylated tripeptide leaves the yeast endoplasmic reticulum by a route different from the secretory pathway, possibly through an ATP-driven pump.
利用分泌蛋白前α因子和含有N-连接糖基化受体位点的合成三肽作为底物，在体外研究了酿酒酵母内质网的蛋白质和肽输出。内质网中糖基化的前α因子和糖基三肽的释放依赖于细胞质、温度和ATP。针对运输小泡形成所必需的两种蛋白质Sec23p和p105的抗体抑制了糖基化前α因子从内质网的输出，但不影响糖基化三肽的释放。此外，与前α因子不同，输出的糖肽不与膜部分相关，也不获得高尔基体特异性的α(1-6)-连接甘露糖残基。我们得出结论，糖基化三肽通过不同于分泌途径的路线离开酵母内质网，可能是通过ATP驱动的泵。
