Csk inhibition of c‐Src activity requires both the SH2 and SH3 domains of Src.
Csk inhibition of c‐Src activity requires both the SH2 and SH3 domains of Src.
复制标题
Csk 抑制 c-Src 活性需要 Src 的 SH2 和 SH3 结构域。
DOI：
10.1002/j.1460-2075.1993.tb05923.x
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Giulio Draetta
中科院分区：
文献类型：
--
作者：
Giulio Superti;Stefano Fumagalli;Manfred Koegi;S. Courtneidge;Giulio Draetta
蛋白酪氨酸激酶c-Src受其羧基末端尾部Tyr 527磷酸化的负调控。一种磷酸化Tyr 527的激酶，称为Csk，最近被鉴定出来。我们在酵母中表达c-Src，以测试Src的SH 2和SH 3结构域在Tyr 527磷酸化所产生的负调节中的作用。在粟酒裂殖酵母中诱导表达c-Src导致细胞死亡。Csk的共表达抵消了这种作用。在SH 2或SH 3结构域突变的Src蛋白与野生型c-Src一样致命，但对Csk不敏感，即使它们是Csk的体内底物。肽结合实验表明，Src蛋白与突变的SH 3结构域采用的构象中的SH 2结构域是不相互作用的尾巴。这些数据支持SH 2结构域-磷酸化尾部相互作用抑制c-Src活性的模型，但将其扩展到包括SH 3结构域的作用。我们认为SH 3结构域通过稳定SH 2结构域-磷酸化尾部相互作用来维持Src分子的折叠、非活性构型。此外，我们在这里描述的系统允许进一步研究酪氨酸激酶在中性背景下的调节，并在一个适合遗传分析的生物体。
The protein tyrosine kinase c‐Src is negatively regulated by phosphorylation of Tyr527 in its carboxy‐terminal tail. A kinase that phosphorylates Tyr527, called Csk, has recently been identified. We expressed c‐Src in yeast to test the role of the SH2 and SH3 domains of Src in the negative regulation exerted by Tyr527 phosphorylation. Inducible expression of c‐Src in Schizosaccharomyces pombe caused cell death. Co‐expression of Csk counteracted this effect. Src proteins mutated in either the SH2 or SH3 domain were as lethal as wild type c‐Src, but were insensitive to Csk, even though they were substrates for Csk in vivo. Peptide binding experiments revealed that Src proteins with mutant SH3 domains adopted a conformation in which the SH2 domain was not interacting with the tail. These data support the model of an SH2 domain‐phosphorylated tail interaction repressing c‐Src activity, but expand it to include a role for the SH3 domain. We propose that the SH3 domain contributes to the maintenance of the folded, inactive configuration of the Src molecule by stabilizing the SH2 domain‐phosphorylated tail interaction. Moreover, the system we describe here allows for further study of the regulation of tyrosine kinases in a neutral background and in an organism amenable to genetic analysis.