G protein-dependent vectorial transportation of receptors, ion channels, and transporters

受体、离子通道和转运蛋白的 G 蛋白依赖性载体运输

基本信息

批准号：
12144202
负责人：
KATADA Toshiaki
金额：
$ 32.77万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2004
项目状态：
已结题

项目摘要

G protein-coupled or tyrosine kinase-linked receptors are involved in the regulations of many signal transductions. After the stimulation of these membrane receptors, not only the receptor molecules themselves but also ion channels or transporters are internalized into the cells through endocytic pathways. Thus, there is vectorial transportation in the membrane trafficking. In this study, we investigated the molecular mechanisms whereby these receptors regulate the vectorial transportation.The major findings obtained in this study are summarized as follows.1) The lipid kinase phosphatidylinositol (PI) 3-OH kinase is synergistically stimulated by different types of membrane receptors, such as G protein-coupled and tyrosine kinase-linked receptors. We have found that the class I (p110beta subtype) PI 3-OH kinase is responsible for the synergistic stimulation and that its adaptor, Gab2, is involved in the signaling through its dual phosphorylation by Src tyrosine kinase and ERK. 2) The small GTPase Rab family are involved in membrane trafficking pathways. We have identified novel members of the RIN family as guanine nucleotide-exchange factors (GEFs) for Rab5. The RIN family, which contains many functional domains, such as SH2, Pro-rich region (binding to SH3), Vps9 (GEF), and RA (Ras-association), appear to act as adaptors or scaffold proteins in early steps of the endocytic pathway. 3) We have also identified novel family of Ras-like small GTPases, Di-Ras, Rheb, which might be involved in membrane trafficking pathways. Rheb expression in culture cells induced formation of the cytoplasmic large vacuoles, which are characterized as late endocytic (late endosome-and lysosome-like) components. Rheb appears to regulate the internalization of glutamate transporter in glial cells.

G蛋白偶联或酪氨酸激酶连接受体参与许多信号转导的调节。这些膜受体受到刺激后，不仅受体分子本身，而且离子通道或转运蛋白也通过内吞途径内化到细胞内。因此，膜运输中存在矢量运输。在本研究中，我们研究了这些受体调节载体运输的分子机制。本研究获得的主要发现总结如下。1）脂质激酶磷脂酰肌醇（PI）3-OH激酶受到不同类型膜的协同刺激受体，例如G蛋白偶联受体和酪氨酸激酶连接受体。我们发现 I 类（p110beta 亚型）PI 3-OH 激酶负责协同刺激，其接头 Gab2 通过 Src 酪氨酸激酶和 ERK 的双重磷酸化参与信号传导。 2) 小GTPase Rab家族参与膜运输途径。我们已经鉴定出 RIN 家族的新成员作为 Rab5 的鸟嘌呤核苷酸交换因子 (GEF)。 RIN 家族包含许多功能域，例如 SH2、Pro 富集区（与 SH3 结合）、Vps9 (GEF) 和 RA（Ras 关联），似乎在蛋白质合成的早期步骤中充当接头蛋白或支架蛋白。内吞途径。 3）我们还鉴定了Ras样小GTP酶的新家族，Di-Ras，Rheb，它们可能参与膜运输途径。培养细胞中的 Rheb 表达诱导细胞质大液泡的形成，其特征为晚期内吞（晚期内体和溶酶体样）成分。 Rheb 似乎调节神经胶质细胞中谷氨酸转运蛋白的内化。