Structure and Inheritance of the endoplasmic reticulum

在所有真核细胞中，内质网（ER）形成高度有孔的管状网络， 在整个细胞体积中扩散，通常位于质膜下方。这种分布 可能对钙信号传导和其他重要的细胞功能至关重要。我们已经采取了基因 进一步了解酵母内质网的动态、结构和遗传机制。我们 迄今为止的工作表明，ER小管在细胞周期开始时从核被膜形成，它们是 通过V型肌球蛋白Myo4p沿沿着肌动蛋白电缆输送到芽中，它们通过 外囊复合物，然后沿沿着细胞皮层扩散形成皮层ER。我们建议Rtn1 p， 一种保守的网状蛋白质家族成员，作为外囊亚单位的受体发挥功能 Sec6p在ER膜上，Rtn1p也用于连接ER和细胞皮质。四个具体目标 计划： 1)我们将分析Rtnlp与外囊的相互作用，定义Rtnlp在ER内的拓扑结构 膜和特定的相互作用，将外囊连接到Rtnlp。 2)我们将确定Rtnlp是否沿着皮层沿着与Tcb 3蛋白结合，以及这种相互作用是否是Tcb 3蛋白的基础。 Rtnlp的独特定位以及ER与细胞皮质的紧密关联。 3)我们将确定是否Rtnlp在形成所有的ER特征性的有孔网状结构中起作用。 真核生物，如果它与其他成分的ER膜在这种能力。 4)我们将表达或微量注射哺乳动物reticulon蛋白的显性负等位基因， 使用RNAi方法抑制四种哺乳动物RTN蛋白的功能。表型分析 将决定Rtnlp的作用及其相互作用是否保守。

In all eukarotic cells, the endoplasmic reticulum (ER) forms a highly fenestrated tubular network that spreads throughout the volume of the cell, often lying just below the plasma membrane. This distribution may be critical for calcium signalling and other important cellular functions. We have taken a genetic approach towards understanding the mechanism of ER dynamics, structure and inheritance in yeast. Our work to date shows that ER tubules form from the nucler envelope at the start of the cell cycle, they are delivered into the bud along actin cables by the type V myosin, Myo4p, they are anchored at the bud tip by the exocyst complex and then spread along the cell cortex to form the cortical ER. We propose that Rtn1 p, a member of the conserved reticulon family of proteins, functions as the receptor for the exocyst subunit Sec6p on the ER membrane and that Rtn1 p also serves to link the ER to the cell cortex. Four specific aims are planned: 1) We will analyze the interaction of Rtnlp with the exocyst, defining the topology of Rtnlp within the ER membrane and the specific interactions that link the exocyst to Rtnlp. 2) We will determine if Rtnlp binds to the Tcb3 protein along the cortex and if this interaction underlies the unique localization of Rtnlp as well as the tight association of the ER with the cell cortex. 3) We will determine if Rtnlp plays a role in forming the fenestrated reticulum characteristic of the ER in all eukaryotes and if it interacts with other components of the ER membrane in this capacity. 4) We will express or microinject dominant negative alleles of mammalian reticulon proteins as well as make use of RNAi methodology to inhibit the function of the four mammalian RTN proteins. Phenotypic analysis will determine if the roles of Rtnlp and its interactions are conserved.