Identification of TBC7 having TBC domain as a novel binding protein to TSC1-TSC2 complex
Identification of TBC7 having TBC domain as a novel binding protein to TSC1-TSC2 complex
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DOI：
10.1016/j.bbrc.2007.07.011
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发表时间：
2007-09-14
影响因子：
3.1
通讯作者：
Yonezawa, Kazuyoshi
中科院分区：
文献类型：
--
作者：
Nakashima, Akio;Yoshino, Ken-ichi;Yonezawa, Kazuyoshi
TBC7是一种TBC (tre2 /Bub2/Cdcl6) I结构域蛋白，通过对转染的哺乳动物细胞中标记有flag表位的TSC1和TSC2免疫沉淀蛋白的肽质量指纹图谱分析，发现TBC7是TSC1-TSC2肿瘤抑制复合物的一种新的结合蛋白。通过共免疫沉淀和pull-down分析分别证实了TBC7与TSC1-TSC2复合物在体内和体外的关联，发现TBC7与TSC1的c端半区结合，这与TSC2的结合位点不同。免疫荧光显微镜和亚细胞分离显示，TBC7与肿瘤抑制复合物在细胞膜内共定位。TBC7的过表达增强了TSC1的泛素化，并增加了位于mtor信号通路的S6激酶对S6蛋白的磷酸化。这些结果表明，TBC7可能通过促进TSC1的下调参与肿瘤抑制复合物的负调控。(C) 2007爱思唯尔公司版权所有。
TBC7, a TBC (Tre-2/Bub2/Cdcl6) I domain protein, was identified as a novel binding protein to the TSC1-TSC2 tumor suppressor complex by peptide mass fingerprinting analysis of the proteins immunoprecipitated with FLAG-epitope tagged TSC1 and TSC2 from the transfected mammalian cells. The in vivo and in vitro association of TBC7 and the TSC1-TSC2 complex was confirmed by the co-immunoprecipitation and pull-down analysis, respectively, and TBC7 was revealed to bind to the C-terminal half region of TSC1, which is distinct from the binding site with TSC2. The immunofluorescence microscopy and subcellular fractionation showed that TBC7 co-localizes with the tumor suppressor complex in the endomembrane. Overexpression of TBC7 enhanced ubiquitination of TSC1 and increased phosphorylation of S6 protein by S6 kinase, that is located in the mTOR-signaling pathway. These results indicate TBC7 could take a part in the negative regulation of the tumor suppressor complex through facilitating the downregulation of TSC1. (C) 2007 Elsevier Inc. All rights reserved.