GOLGI TARGETING AND RETENTION OF YEAST KEX2 PROTEASE

决定蛋白质的信号的性质和作用机制 在细胞中定位是真核细胞研究的主要焦点 生物学 这个项目的总体目标是阐明在分子 详细说明了跨膜蛋白的信号依赖机制 定位于真核细胞中的反式高尔基体网络（TGN）， 以Kex 2蛋白酶在酵母中的定位为模型。 Kex 2 p是 一个重要的前蛋白加工蛋白酶家族的原型， 在所有真核生物中分泌途径的晚期隔室中起作用 细胞 因此，本研究不仅对认识 它可以提供信号相关定位的一般原理 在分泌途径，但也因为重要性， 了解前蛋白质加工的细胞组织， 涉及到一系列的正常和病理现象 在生物学上。 在目前的融资期间，我们取得了重大进展。 在几个领域取得进展。 我们已经确定了三个基因，SOI 1，SOI 2 和SOI 3，参与Kex 2 p和其他跨膜蛋白的定位。 酵母TGN的蛋白质。 我们已详细研究 SOI 1基因的功能，我们发现它编码一种新的，保守的 一种3144个残基的蛋白质，似乎在TGN和 前液泡室（PVC，相当于 动物细胞）以促进Kex 2 p和其它TGN膜的循环 蛋白质在两个区域之间。 我们已经确认了两个TGN 在Kex 2 p胞质尾中的定位信号（TLS）。 Soilp是 显示通过TLS 1起作用，以促进从细胞中检索Kex 2 p。 PVC和功能在TGN，以抑制TLS 2依赖性的保留， Kex 2 p在TGN中。 这里提出的工作将扩展这些结果 这两种方法都是为了识别参与信号依赖性 TGN膜蛋白的定位和测试TGN-PVC的方面 循环模型 该项目的具体目标是： 1.对酵母进行分子遗传和生化分析 Soilp和高等细胞Soilp同系物; 2.利用基因和生物信息学技术鉴定与Soilp相互作用的蛋白质， 生物化学方法; 3.克隆和分析SOI 2和SOI 3基因; 4.鉴定和研究参与TGN定位的其他基因 通过分离Tyr 713 Ala突变的多拷贝抑制子， 在Kex 2 p TLS 1和TLS 2所需的基因的鉴定 功能

The nature and mechanism of action of signals that determine protein localization in cells are a primary focus of research in eukaryotic cell biology. The overall goal of this project is to elucidate in molecular detail the signal-dependent mechanisms by which transmembrane proteins are localized to the trans Golgi network (TGN) in eukaryotic cells, using localization of Kex2 protease in yeast as a model. Kex2p is the prototype of an important family of proprotein-processing proteases that function in late compartments of the secretory pathway in all eukaryotic cells. Thus this research is of significance not only for the knowledge it may provide about general principles of signal-dependent localization in the secretory pathway, but also because of the importance of understanding the cellular organization of proprotein processing, which is involved in a wide array of both normal and pathological phenomena in biology. During the current funding period, we have made significant progress in several areas. We have identified three genes, SOI1, SOI2 and SOI3, involved in localization of Kex2p and other transmembrane proteins to the yeast TGN. We have conducted detailed studies of the function of the SOI1 gene, which we found to encode a novel, conserved protein of 3144 residues that appears to function at both the TGN and the prevacuolar compartment (PVC, equivalent to the late endosome in animal cells) to promote the cycling of Kex2p and other TGN membrane proteins between the two compartments. We have identified two TGN localization signals (TLSs) in the Kex2p cytosolic tail. Soilp was shown to function through TLS1 to promote retrieval of Kex2p from the PVC and to function at the TGN to inhibit TLS2-dependent retention of Kex2p in the TGN. The work proposed here will expand on these results both to identify additional molecules involved in signal-dependent localization of TGN membrane proteins and to test aspects of the TGN-PVC cycling model. The specific aims of the project are: 1. to pursue a molecular, genetic and biochemical analysis of yeast Soilp and higher cell Soilp homologues; 2. to identify proteins that interact with Soilp using both genetic and biochemical approaches; 3. to clone and analyze the SOI2 and SOI3 genes; and 4. to identify and study additional genes involved in TGN localization through the isolation of multicopy suppressors of the Tyr713Ala mutation in the Kex2p TLS1 and identification of genes required for TLS2 function.