The Arrest of Secretion Response

最近对酵母中的“分泌反应停滞”（ASR）的观察记录了一种新形式的细胞内信号传导：启动信号的蛋白质，尽管它通常位于细胞表面，但必须被捕获在细胞内区室中才能发出信号。本计画将探讨沿着此信号传导路径运作的分子机制。在ASR中，sec突变体中沿分泌路径沿着运输的抑制使核孔复合物（NPC）的蛋白质重新定位，抑制核输入并且还使核质蛋白质重新定位到细胞质。蛋白激酶C（Pkc1p）和Wsc家族的两种跨膜蛋白是这些事件所必需的。然而，它们不需要Pkc1p MAP激酶级联。此外，与那些通常位于质膜上的Wsc蛋白相反，沿着分泌途径捕获的Wsc蛋白是信号传导所需的。因此，这项工作将确定 * Pkc1p是否与Wsc蛋白相关，以及这种相关性是否取决于是否发生主动ASR，* 当分泌途径被抑制时，即在ASR期间，是否产生二酰基甘油，* 遗传筛选是否可以识别所需的信号传导中间体，特别是那些在Pkc1p下游发挥作用的中间体。

Recent observations on the "arrest of secretion response" (ASR) in yeast have documented a novel form of intracellular signaling: the protein which initiates the signal, although it is normally at the cell surface, must be trapped within intracellular compartments in order to signal. This project will explore molecular mechanisms which operate along this signaling pathway. In the ASR, inhibition of transport along the secretory path in sec mutants relocates proteins of the nuclear pore complex (NPC), inhibits nuclear import and also relocates nucleoplasmic proteins to the cytoplasm. Protein kinase C (Pkc1p) and two of the transmembrane proteins of the Wsc family are required for these events. They nevertheless do not require the Pkc1p MAP kinase cascade. Moreover, Wsc proteins trapped along the secretory path are required for signaling, as opposed to those which are normally at the plasma membrane. Thus, this work will determine * Whether Pkc1p associates with Wsc proteins and whether such association depends on whether an active ASR is occurring, * Whether diacylglycerol is generated when the secretory path is inhibited, i.e. during the ASR, * Whether a genetic screen can identify signaling intermediates which are required, especially those which function downstream of Pkc1p.