Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA.
Proc Natl Acad Sci U S A. 2009 Dec 15;106(50):21143-8. doi: 10.1073/pnas.0911309106. Epub 2009 Dec 1.
Interleukin-2 tyrosine kinase (Itk) is a Tec family tyrosine kinase that mediates signaling processes after T cell receptor engagement. Activation of Itk requires recruitment to the membrane via its pleckstrin homology domain, phosphorylation of Itk by the Src kinase, Lck, and binding of Itk to the SLP-76/LAT adapter complex. After activation, Itk phosphorylates and activates phospholipase C-gamma1 (PLC-gamma1), leading to production of two second messengers, DAG and IP(3). We have previously shown that phosphorylation of PLC-gamma1 by Itk requires a direct, phosphotyrosine-independent interaction between the Src homology 2 (SH2) domain of PLC-gamma1 and the kinase domain of Itk. We now define this docking interface using a combination of mutagenesis and NMR spectroscopy and show that disruption of the Itk/PLCgamma1 docking interaction attenuates T cell signaling. The binding surface on PLCgamma1 that mediates recognition by Itk highlights a nonclassical binding activity of the well-studied SH2 domain providing further evidence that SH2 domains participate in important signaling interactions beyond recognition of phosphotyrosine.
白细胞介素-2 酪氨酸激酶 (Itk) 是 Tec 家族酪氨酸激酶，可介导 T 细胞受体结合后的信号转导过程。Itk 的激活需要通过其 pleckstrin 同源结构域募集到膜上，Src 激酶 Lck 磷酸化 Itk，以及 Itk 与 SLP-76/LAT 衔接子复合物结合。激活后，Itk 磷酸化并激活磷脂酶 C-γ1 (PLC-γ1)，导致两种第二信使 DAG 和 IP(3)的产生。我们之前已经表明，Itk 对 PLC-γ1 的磷酸化需要 PLC-γ1 的Src 同源 2 (SH2)结构域与 Itk 的激酶结构域之间直接、非磷酸酪氨酸依赖的相互作用。我们现在使用突变和 NMR 光谱学的组合来定义这个对接界面，并表明 Itk/PLCgamma1 对接相互作用的破坏会减弱 T 细胞信号转导。PLC-γ1 介导 Itk 识别的结合表面突出了经过充分研究的 SH2 结构域的非经典结合活性，进一步证明 SH2 结构域参与了除识别磷酸酪氨酸之外的重要信号转导相互作用。
