Jui H Y, Tseng R J, Wen X, Fang H I, Huang L M, Chen K Y, Kung H J, Ann D K, Shih H M
Division of Molecular and Genomic Medicine, National Health Research Institutes, and the Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 11529, Taiwan.
J Biol Chem. 2000 Dec 29;275(52):41124-32. doi: 10.1074/jbc.M007772200.
Etk, also named Bmx, is a member of the Tec tyrosine kinase family, which is characterized by a multimodular structure including a pleckstrin homology (PH) domain, an SH3 domain, an SH2 domain, and a catalytic domain. The signaling mechanisms regulating Etk kinase activity remain largely unknown. To identify factor(s) regulating Etk activity, we used the PH domain and a linker region of Etk as a bait for a yeast two-hybrid screen. Three independent clones encoding protein-tyrosine phosphatase D1 (PTPD1) fragments were isolated. The binding of PTPD1 to Etk is specific since PTPD1 cannot associate with either the Akt PH domain or lamin. In vitro and in vivo binding studies demonstrated that PTPD1 can interact with Etk and that residues 726-848 of PTPD1 are essential for this interaction. Deletion analysis of Etk indicated that the PH domain is essential for PTPD1 interaction. Furthermore, the Etk-PTPD1 interaction stimulated the kinase activity of Etk, resulting in an increased phosphotyrosine content in both factors. The Etk-PTPD1 interaction also increased Stat3 activation. The effect of PTPD1 on Etk activation is specific since PTPD1 cannot potentiate Jak2 activity upon Stat3 activation. In addition, Tec (but not Btk) kinase can also be activated by PTPD1. Taken together, these findings indicate that PTPD1 can selectively associate with and stimulate Tec family kinases and modulate Stat3 activation.
Etk，也称为Bmx，是Tec酪氨酸激酶家族的成员，其特征在于多模块结构，包括普列克底物蛋白同源性（PH）结构域、SH3结构域、SH2结构域和催化结构域。调节Etk激酶活性的信号传导机制在很大程度上仍然未知。为了鉴定调节Etk活性的因子，我们使用Etk的PH结构域和连接区作为酵母双杂交筛选的诱饵。分离出三个编码蛋白酪氨酸磷酸酶D1（PTPD1）片段的独立克隆。PTPD1与Etk的结合是特异性的，因为PTPD1不能与Akt PH结构域或核纤层蛋白结合。体外和体内结合研究表明，PTPD1可以与Etk相互作用，并且PTPD1的726-848位残基对于这种相互作用至关重要。Etk的缺失分析表明，PH结构域对于PTPD1相互作用至关重要。此外，Etk-PTPD1相互作用刺激了Etk的激酶活性，导致两个因子中磷酸酪氨酸含量增加。Etk-PTPD1相互作用也增加了Stat3的激活。PTPD1对Etk激活的作用是特异性的，因为在Stat3激活时PTPD1不能增强Jak2活性。此外，Tec（但不是Btk）激酶也可以被PTPD1激活。综上所述，这些发现表明PTPD1可以选择性地与Tec家族激酶结合并刺激它们，并调节Stat3的激活。
