Structure and Inheritance of the endoplasmic reticulum

在所有真核生物细胞中，内质网(ER)形成一个高度开窗的管状网络 在整个细胞体积内扩散，通常位于质膜下方。此分布 可能对钙信号和其他重要的细胞功能至关重要。我们提取了一种基因 了解酵母内质网动态、结构和遗传机制的途径。我们的 到目前为止的工作表明，内质网小管在细胞周期开始时从核膜形成，它们是 它们通过V型肌球蛋白Myo4p沿着肌动蛋白电缆传递到芽中，由 胞囊复合体，然后沿细胞皮质扩散形成皮质内质网。我们建议Rtn1p， 一种保守的网状蛋白家族的成员，作为胞外囊泡亚单位的受体发挥作用 Sec6p在内质网膜上，Rtn1p也起到连接内质网和细胞皮质的作用。四个具体目标 计划： 1)我们将分析Rtnlp与胞囊的相互作用，定义Rtnlp在内质网内的拓扑结构 膜和连接外囊与Rtnlp的特定相互作用。 2)我们将确定Rtnlp是否沿着皮质与Tcb3蛋白结合，以及这种相互作用是否支持 Rtnlp的独特定位以及ER与细胞皮质的紧密联系。 3)我们将确定Rtnlp是否在形成内质网特征的有窗网状结构中起作用 如果它与内质网膜的其他成分以这种能力相互作用。 4)我们将表达或显微注射哺乳动物网状蛋白的显性负等位基因，并制作 利用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.