The kinase Itk and the adaptor TSAd change the specificity of the kinase Lck in T cells by promoting the phosphorylation of Tyr192
The kinase Itk and the adaptor TSAd change the specificity of the kinase Lck in T cells by promoting the phosphorylation of Tyr192
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DOI：
10.1126/scisignal.2005384
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发表时间：
2014-12-09
影响因子：
7.3
通讯作者：
Spurkland, Anne
中科院分区：
文献类型：
--
作者：
Granum, Stine;Sundvold-Gjerstad, Vibeke;Spurkland, Anne
Src家族激酶（SFK）的底物特异性部分由其Src同源2（SH 2）结构域决定。因此，SFKs的SH 2结构域的瞬时改变可能改变其结合伴侣并影响细胞内信号传导途径。Lck是一种SFK，其对于响应于配体结合至T细胞受体（TCR）而启动T细胞活化至关重要，并且对于后续信号传导过程也至关重要。Lck的激酶活性需要活化酪氨酸残基的磷酸化和抑制酪氨酸残基的去磷酸化。我们发现Lck的SH 2结构域内的第三个保守的酪氨酸磷酸化位点（Tyr（192））是T细胞适当激活以及T细胞和抗原呈递细胞之间形成细胞-细胞缀合物所必需的。通过磷酸肽阵列和生化分析，我们确定了几个调节肌动蛋白细胞骨架，优先结合LCK磷酸化的Tyr（192）相比，LCK没有磷酸化在这个网站。这些磷酸化依赖性结合配偶体中的两种，激酶Itk（白细胞介素-2诱导型Tec激酶）和衔接蛋白TSAd（T细胞特异性衔接子），促进Lck在Tyr处的TCR依赖性磷酸化（192）。我们的数据表明，磷酸化瞬时改变SH 2结构域的特异性，并提供了一个潜在的机制，SFKs可以重新连接从一个信号程序到另一个，使适当的细胞激活。
The substrate specificity of Src family kinases (SFKs) is partly determined by their Src homology 2 (SH2) domains. Thus, transient alterations in the SH2 domain of SFKs might change their binding partners and affect intracellular signaling pathways. Lck is an SFK that is central to the initiation of T cell activation in response to ligand binding to the T cell receptor (TCR) and is also critical for later signaling processes. The kinase activity of Lck requires both the phosphorylation of an activating tyrosine residue and the dephosphorylation of an inhibitory tyrosine residue. We found that a third conserved tyrosine phosphorylation site (Tyr(192)) within the SH2 domain of Lck was required for proper T cell activation and formation of cell-cell conjugates between T cells and antigen-presenting cells. Through phosphopeptide arrays and biochemical assays, we identified several regulators of the actin cytoskeleton that preferentially bound to Lck phosphorylated at Tyr(192) compared to Lck that was not phosphorylated at this site. Two of these phosphorylation-dependent binding partners, the kinase Itk (interleukin-2-inducible Tec kinase) and the adaptor protein TSAd (T cell-specific adaptor), promoted the TCR-dependent phosphorylation of Lck at Tyr(192). Our data suggest that phosphorylation transiently alters SH2 domain specificity and provide a potential mechanism whereby SFKs may be rewired from one signaling program to another to enable appropriate cell activation.