SAP increases FynT kinase activity and is required for phosphorylation of SLAM and Ly9
SAP increases FynT kinase activity and is required for phosphorylation of SLAM and Ly9
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DOI：
10.1093/intimm/dxh074
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发表时间：
2004-05-01
影响因子：
4.4
通讯作者：
Terhorst, C
中科院分区：
文献类型：
--
作者：
Simarro, M;Lanyi, A;Terhorst, C
由X连锁淋巴增生性疾病基因SH2D1A编码的游离Src同源2（SH2）结构域蛋白SAP控制由T和NK细胞中的SLAM相关受体的接合引发的信号转导。在这里，我们证明了SAP是胸腺细胞和外周T细胞中SLAM和Ly9磷酸化所必需的。此外，体外蛋白质相互作用研究和酵母双杂交分析表明，SAP直接结合FynT和Lck。SAP与FynT的SH3结构域和激酶结构域结合，而SAP仅与Lck的激酶结构域结合。SAP与FynT的SH3结构域之间存在强相互作用，这促使我们研究SAP在调节FynT活性中的作用。在体外添加SAP的FynT的自抑制形式引起了FynT催化活性的大幅增加。相比之下，SAP突变体R78E，其不能结合FynT SH3结构域，不增加FynT活性，并且在转染到T细胞中时也显示出降低的衔接子功能。我们的研究结果表明，SAP是一个衔接SLAM和Ly9与Src样蛋白酪氨酸激酶（PTKs），并有能力激活FynT。
The free Src homology 2 (SH2) domain protein SAP, encoded by the X-linked lymphoproliferative disease gene SH2D1A, controls signal transduction initiated by engagement of the SLAM-related receptors in T and NK cells. Here we demonstrate that SAP is required for phosphorylation of both SLAM and Ly9 in thymocytes and peripheral T cells. Furthermore, in vitro protein interaction studies and yeast two-hybrid analyses indicated that SAP binds directly to FynT and Lck. While SAP bound to both the SH3 domain and to the kinase domain of FynT, SAP bound solely to the kinase domain of Lck. The existence of a strong interaction between SAP and the SH3 domain of FynT prompted us to study the role of SAP in modulating the activity of FynT. In vitro addition of SAP to the autoinhibited form of FynT caused a large increase in FynT catalytic activity. By contrast, the SAP mutant R78E, which is unable to bind to the FynT SH3 domain, did not increase FynT activity and also displayed a reduced adaptor function upon transfection into T cells. Our results demonstrate that SAP is an adaptor that bridges SLAM and Ly9 with Src-like protein tyrosine kinases (PTKs), and has the ability to activate FynT.