Roles of ubiquitin protein ligases in endocytosis

泛素蛋白连接酶在内吞作用中的作用

• 批准号: 6702239
• 负责人: Linda A. Hicke
• 金额: $ 22.79万
• 依托单位: NORTHWESTERN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-03-01 至 2006-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6702239
• 关键词: active sites; cell membrane; endocytosis; enzyme activity; enzyme structure; enzyme substrate; fungal proteins; intracellular transport; ligase; membrane proteins; mutant; protein degradation; protein protein interaction; protein structure function; transcription factor; ubiquitin; yeasts

DESCRIPTION (provided by applicant): The ubiquitination of many cell surface regulatory proteins is critical for their downregulation because ubiquitin signals control internalization and sorting of proteins in the endocytic pathway. Ubiquitin protein ligases are key components of the ubiquitination machinery that recognize and modify specific plasma membrane substrates at the appropriate time to initiate downregulation. These ligases play multiple roles in endocytosis: they are required to ubiquitinate endocytic cargo, they modify trans-acting components of the endocytic machinery, and they control transport of proteins later in the endocytic pathway. When plasma membrane proteins cannot be recognized and modified by ubiquitin protein ligases, human diseases, such as cancers and an inherited form of hypertension (Liddls syndrome), occur. The Nedd4/Rsp5p family of hect ubiquitin protein ligases modify and downregulate signaling receptors, channels and permeases. Nedd4/Rsp5p carries a C2 domain, which may be involved in Ca+2-dependent interactions with phospholipids or proteins, three WW protein-protein interaction motifs, and a catalytic hect domain. Nedd4 is required for ubiquitination and endocytosis of the epithelial sodium channel. Other C2-WW-hect domain ligases ubiquitinate and/or regulate Notch and TGFB receptors. The yeast homologue of these ligases, Rsp5p, ubiquitinates phosphorylated plasma membrane proteins to trigger rapid endocytosis. We have recently shown that trans-acting endocytic proteins that are required for internalization and endosomal transport are also ubiquitinated by Rsp5p. For example, we have identified one component of the endocytic machinery, an amphiphysin homologue called Rvsl67p, as a target of Rsp5p-dependent monoubiquitination. The experiments described in this grant are proposed to define the roles of hect domain ubiquitin protein ligases at multiple steps in the endocytic pathway that lead to downregulation and degradation of cell surface regulatory proteins. The aims of the grant are 1) to define how the Rsp5p ubiquitin protein ligase recognizes and ubiquitinates phosphorylated receptors; 2) to identify trans-acting factors of the endocytic machinery that are regulated by Rsp5p-dependent ubiquitination; and 3) to define the cellular and molecular functions of Rsp5p-dependent monoubiquitination of the amphiphysin homologue, Rvsl67p.

描述（由申请人提供）：许多细胞表面的泛素化 调节蛋白对于下调至关重要，因为泛素 信号控制内吞蛋白质的内在化和分类 路径。泛素蛋白连接酶是泛素化的关键组成部分 识别和修改特定质膜底物的机械 适当的时间开始下调。这些连接酶扮演多个角色 在内吞作用：它们是泛素式内吞货物所必需的，它们会修改 内吞机械的跨作用组件，它们控制运输 蛋白质的后期在内吞途径中。当质膜蛋白 无法通过泛素蛋白连接酶，人类疾病来识别和修饰 例如癌症和遗传形式的高血压（Liddls综合征）。 NEDD4/RSP5P Hect泛素蛋白连接酶的nedd4/Rsp5p家族修饰和 下调信号受体，通道和倒入。 NEDD4/RSP5P携带a C2域，可能与Ca+2依赖性相互作用与 磷脂或蛋白质，三个WW蛋白 - 蛋白质相互作用基序和A 催化Hect结构域。 NEDD4是泛素化和内吞作用所必需的 上皮钠通道。其他C2-ww-hect域连接酶泛素化 和/或调节缺口和TGFB受体。这些连接酶的酵母同源物， RSP5P，泛素化磷酸化的质膜蛋白触发快速 内吞作用。我们最近表明，跨作用的内吞蛋白 内在化和内体运输所必需的也需要泛素化 由RSP5P。例如，我们确定了内吞的一个成分 机械，一种称为RVSL67P的两亲动物同源物，作为目标 依赖RSP5P的单泛素化。 提出了本赠款中描述的实验来定义 在内吞的多个步骤上，hect结构域的泛素蛋白连接酶 导致细胞表面调节下调和降解的途径 蛋白质。赠款的目的是1）定义RSP5P泛素的方式 蛋白质连接酶识别并泛素化磷酸化受体。 2）到 识别受内吞机械的跨作用因子的调节 依赖RSP5P的泛素化； 3）定义细胞和分子 RSP5P依赖性的单倍素化的功能，两亲素同源物的功能， RVSL67P。