Charakterisierung eines neuen Sortierungsweges für ein Protein der Plasmamembran

真核细胞主要通过分泌途径生成质膜蛋白（PM）。这条运输路线从膜蛋白插入内质网（ER）膜开始，然后是货物的囊泡运输到高尔基体，并分拣到最终目的地。最近的研究表明，一些分泌蛋白和膜蛋白是独立于sec途径进行分类的。这些过程背后的分子机制尚不清楚。在酵母菌中，在子细胞周围的内质网附近发现了一个定位的mRNA，该mRNA编码多位膜蛋白Ist2p。我们已经证明Ist2p向PM的传递独立于sec介导的ER到高尔基体、高尔基体内和高尔基体到PM的转运，这表明Ist2p通过一种新的转运途径到达PM。将蛋白质定义为这种新型Ich通路的货物的特性以及介导其运输的因素尚不清楚。因此，我们的目标是表征Ist2p的分选信号，它介导了对PM的非sec独立转运，我们将通过酵母遗传学确定相关因素。

Eukaryotic cells mainly use the secretory (sec)-pathway for the biogenesis of plasma membrane (PM) proteins. This transport route begins with the insertion of membrane proteins into the membrane of the endoplasmic reticulum (ER), followed by the vesicular transport of cargo to the Golgi-apparatus and the sorting to the final destination. Recent studies have suggested that some secreted and membrane proteins are sorted independently of the sec-pathway. The molecular mechanisms underlying these processes are unknown. In the yeast Saccharomyces cerevisiae, the polytopic membrane protein Ist2p is encoded by a localized mRNA that has been found in proximity of the ER at the periphery of daughter cells. We have shown hat the delivery of Ist2p to the PM is independent of sec-mediated ER to Golgi-, intra-Golgi and Golgi to PM-transport suggesting that Ist2p travels on a novel trafficking pathway to the PM. The properties of proteins that define them as cargo for this novel Ich denkepathway and the factors that mediate their trafficking are unknown. Therefore we aim to characterize the sorting signals of Ist2p, which mediate the sec-independent transport to the PM, and we are going to identify the involved factors by employing yeast genetics.