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Intracellular signal transduction by SH3 domain-containing proteins

含有 SH3 结构域的蛋白质的细胞内信号转导

基本信息

批准号：
09670134
负责人：
SUMIMOTO Hideki
金额：
$ 1.92万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

In this project we have studied molecular mechanism by which p47^<phox> and p67^<phox>, each containing two SH3 domains, activate the phagocyte NADPH oxidase, to obtain the following results. (1) The SH3 domains of p47^<phox> are masked via intramolecular interaction with its C-terminal region. The interaction is disrupted by arachidonic acid or by phosphorylation of three serine residues in the p47^<phox> C-terminus, which allows the domains to bind to cytochrome b_<558>, the enzymatic core of the oxidase. The intermolecular interaction functions as a switch for the oxidase activation. (2) The two SH3 domains are tandemly arranged with a linker of 10 amino acid residues. The length of the linker plays an important role in both intramolecular and intermolecular interactions. (3) Another switch for the activation is conversion of the small GTPase Rac to the GTP-bound active state, which leads to interaction with p67^<phox>. This binding is mediated via the TPR domain of the latter protein. (4) We have developed a novel method to detect the GTP-bound Rac at a cell level. Using this procedure, we find that Rac activation of human neutrophils stimulated with G1-coupled receptor agonists requires phosphoinositide 3-kinase. (5) Discovered is a novel module in the N-terminus of p47P^<phox>, designated PB2 domain, that positively regulates the oxidase activation. (6) The oxidase regulator p4O^<phox> constitutively associates with p67^<phox>, which is mediated via a novel type of interaction between two modules that are discoverd in this project : the PB 1 domain of p67PhOx and the PC motif of p40^<phox>.

在本项目中，我们研究了含有两个SH3结构域的p47^&lt；Phox&gt；和p67^&lt；Phox&gt；激活吞噬细胞NADPH氧化酶的分子机制，得到了以下结果。(1)P47^&lt；Phox&gt；的SH3结构域通过与其C-末端区域的分子内相互作用而被屏蔽。这种相互作用被花生四烯酸或P47^&lt；Phox&gt；C-末端的三个丝氨酸残基的磷酸化所破坏，这使得结构域能够与细胞色素b_&lt；558&gt；，氧化酶的酶核心结合。分子间相互作用起到了酶活性开关的作用。(2)两个SH3结构域由10个氨基酸残基组成的连接子串联排列。连接子的长度在分子内和分子间的相互作用中都起着重要的作用。(3)激活的另一个开关是将小的GTP酶Rac转换到GTP结合的活性状态，从而导致与p67；这种结合是通过后一种蛋白的TPR结构域介导的。(4)我们开发了一种在细胞水平上检测GTP结合的RAC的新方法。利用这一过程，我们发现，用G1偶联受体激动剂刺激的人中性粒细胞的RAC激活需要磷脂酰肌醇3-激酶。(5)在p47P^&lt；Phox&gt；的N-末端发现了一个新的模块，命名为PB2结构域，它正向调节氧化酶的激活。(6)氧化酶调节子p4O；；Phox&gt；与p67^&lt；Phox&gt；通过本项目中发现的两个模块之间的一种新型相互作用：p67PhOx的PB1结构域和p40^&lt；Phox&gt；的PC基序介导。