p140Sra-1 (specifically Rac1-associated protein) is a novel specific target for Rac1 small GTPase
p140Sra-1 (specifically Rac1-associated protein) is a novel specific target for Rac1 small GTPase
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DOI：
10.1074/jbc.273.1.291
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发表时间：
1998-01-02
影响因子：
4.8
通讯作者：
Kaibuchi, K
中科院分区：
文献类型：
--
作者：
Kobayashi, K;Kuroda, S;Kaibuchi, K
Rac1小GTPase在细胞形态、细胞极性和细胞增殖等多种细胞功能中发挥着关键作用，我们之前通过亲和纯化方法从牛脑细胞质中鉴定出IQGAP1作为Rad的靶标，通过使用相同的方法，我们从牛脑细胞质中纯化了分子量约为140 kDa（p140）的特异性Rac1相关蛋白， 该蛋白与鸟苷 5'-(3-O-硫代)三磷酸 (GTP gamma S).谷胱甘肽 S-转移酶 (GST)-Rac1 相互作用，但不与 GDP.GST-Rac1、GTP gamma S.GST-Cdc42 或 GTP gamma S.GST-RhoA 相互作用。该蛋白的氨基酸序列显示p140被鉴定为KIAA0068基因的产物，我们将该蛋白命名为Sra-1（具体为Rad相关蛋白），重组Sra-1与GTP gamma S.GST-Rac1相互作用，与GDP.Rac1有弱相互作用，但与GST-Cdc42或GST-RhoA不相互作用，Sra-1的N端结构域 （1-407 个氨基酸）负责与 Rad 的相互作用。 Myc标记的Sra-1和能够与Rad相互作用的缺失突变体，但不能与Rad相互作用的突变体，与显性活性Rac1（Val-12）和皮质肌动蛋白丝共定位于KB细胞中Rac1（Val-12）诱导的膜波纹区，Sra-1与丝状肌动蛋白（F-肌动蛋白）共沉淀，表明Sra-1直接与F-肌动蛋白相互作用，这些结果 表明 Sra-1 是 Rac1 的一个新颖且特异的靶标。
Rac1 small GTPase plays pivotal roles in various cell functions such as cell morphology, cell polarity, and cell proliferation, We have previously identified IQGAP1 from bovine brain cytosol as a target for Rad by an affinity purification method, By using the same method, we purified a specifically Rac1-associated protein with a molecular mass of about 140 kDa (p140) from bovine brain cytosol, This protein interacted with guanosine 5'-(3-O-thio)triphosphate (GTP gamma S).glutathione S-transferase (GST)-Rac1 but not with the GDP.GST-Rac1, GTP gamma S.GST-Cdc42, or GTP gamma S.GST-RhoA. The amino acid sequences of this protein revealed that p140 is identified as a product of KIAA0068 gene, We denoted this protein as Sra-1 (Specifically Rad-associated protein), Recombinant Sra-1 interacted with GTP gamma S.GST-Rac1 and weakly with GDP.Rac1 but not with GST-Cdc42 or GST-RhoA, The N-terminal domain of Sra-1 (1-407 amino acids) was responsible for the interaction with Rad. Myc-tagged Sra-1 and the deletion mutant capable of interacting with Rad, but not the mutants unable to bind Rad, were colocalized with dominant active Rac1(Val-12) and cortical actin filament at the Rac1(Val-12)-induced membrane ruffling area in KB cells, Sra-1 was cosedimented with filamentous actin (F-actin), indicating that Sra-1 directly interacts with F-actin, These results suggest that Sra-1 is a novel and specific target for Rac1.