Direct binding of p130Cas to the guanine nucleotide exchange factor C3G
Direct binding of p130Cas to the guanine nucleotide exchange factor C3G
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DOI：
10.1074/jbc.273.40.25673
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发表时间：
1998-10-02
影响因子：
4.8
通讯作者：
Hanafusa, H
中科院分区：
文献类型：
--
作者：
Kirsch, KH;Georgescu, MM;Hanafusa, H
p130（Cas）（Cas; crk相关底物）属于一个新的对接分子家族。它在其氨基末端区域含有一个Src同源（SH）3结构域，随后是含有SH 2和SH 3结构域结合基序的区域。为了进一步了解Cas信号传导，我们在双杂交筛选中使用Cas的SH 3结构域来搜索人胎盘文库中的结合伴侣。该筛选证实了先前发现的其与粘着斑激酶（FAK）结合，但也鉴定了C3 G，一种鸟嘌呤核苷酸交换因子。我们发现Cas和C3 G在体外和体内直接相互作用。对C3 G缺失突变体的一系列分析显示，富含脯氨酸的Gas结合位点（Ala（0）-Pro（1）-Pro（2）-Lys（3）-Pro（4）-Pro（5）-Leu（6）-Pro（7））位于C3 G中先前表征的Crk结合基序的NH 2端。突变研究表明，配体结合位点内的Pro（1）、Lys（3）和Pro（4）对于高亲和力相互作用至关重要。这些结果与来自已知用于Cas结合的蛋白质的富含脯氨酸的结合元件的序列比对相结合，定义了由CasSH 3结构域识别的共有序列XXPXKPX。Cas显示了对接分子的结构特征，并且可以用于将C3 G带到细胞内的特定隔室。
p130(Cas) (Cas; crk-associated substrate) belongs to a new family of docking molecules. It contains one Src homology (SH) 3 domain in its amino terminal region followed by a region containing binding motifs for SH2 and SH3 domains. To gain further insight into Cas signaling we used the SH3 domain of Cas in a two-hybrid screen to search a human placenta library for binding partners. The screen confirmed a previous finding of its binding to the focal adhesion kinase (FAK) but also identified C3G, a guanine nucleotide exchange factor. We found direct interaction between Cas and C3G in vitro and in vivo. A series of analysis with C3G deletion mutants revealed a proline-rich Gas-binding site (Ala(0)-Pro(1)-Pro(2)-Lys(3)-Pro(4)-Pro(5)-Leu(6)-Pro(7)) located NH2-terminal to the previously characterized Crk binding motifs in C3G. Mutagenesis studies showed that Pro(1), Lys(3), and Pro(4) within the ligand-binding site are critical for high affinity interaction. These results, combined with sequence alignments of proline-rich binding elements from proteins known for Cas binding, define the consensus sequence XXPXKPX which is recognized by the CasSH3 domain. Cas shows structural characteristics of a docking molecule and may serve to bring C3G to specific compartments within the cell.