Adaptor protein 3BP2 is a potential ligand of Src homology 2 and 3 domains of Lyn protein-tyrosine kinase
Adaptor protein 3BP2 is a potential ligand of Src homology 2 and 3 domains of Lyn protein-tyrosine kinase
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DOI：
10.1074/jbc.m301201200
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发表时间：
2003-07-04
影响因子：
4.8
通讯作者：
Yamamura, H
中科院分区：
文献类型：
--
作者：
Maeno, K;Sada, K;Yamamura, H
衔接蛋白3BP 2是一种c-Abl-Src同源3（SH 3）结构域结合蛋白，已知其通过与Syk/ZAP-70蛋白酪氨酸激酶相互作用，在T细胞受体介导的活化T细胞核因子和激活蛋白1的转录激活中发挥调节作用。我们先前已经证明高亲和力IgE受体（FcRepsilonI）的聚集诱导3BP 2的酪氨酸磷酸化，并且3BP 2-SH 2结构域的过表达抑制大鼠嗜碱性白血病RBL-2 H3肥大细胞系中抗原诱导的脱粒。在这份报告中，我们试图分析3BP 2酪氨酸磷酸化的生物学相关性。通过在COS-7细胞中使用瞬时表达系统，我们已经证明，当与Syk共表达时，3BP 2主要在Tyr（174）、Tyr（183）和Tyr（446）上磷酸化。体外结合研究显示，Syk对Tyr（446）的磷酸化可能在RBL-2 H3细胞中产生Lyn-SH 2结构域的结合位点。此外，3BP 2的富含脯氨酸的区域与Lyn-SH 3结构域结合。构象显微镜分析表明，林恩和3BP 2组成型共定位在RBL-2 H3细胞中。在RBL-2 H3细胞中过表达3BP 2导致林恩自身磷酸化增强。这些结果表明，衔接蛋白3BP 2是林恩蛋白酪氨酸激酶的潜在调节剂，作为其SH 3/SH 2结构域在肥大细胞中Fc ε RI介导的信号传导中的配体。
Adaptor protein 3BP2, a c-Abl-Src homology 3 (SH3) domain-binding protein, is known to play a regulatory role in T-cell receptor-mediated transcriptional activation of nuclear factor of activated T cell and activator protein 1 by interacting with Syk/ZAP-70 protein-tyrosine kinase. We have previously demonstrated that aggregation of high affinity IgE receptor (FcRepsilonI) induces tyrosine phosphorylation of 3BP2, and overexpression of the 3BP2-SH2 domain suppresses antigen- induced degranulation in rat basophilic leukemia RBL-2H3 mast cell line. In this report, we attempt to analyze the biological relevance of 3BP2 tyrosine phosphorylation. By using the transient expression system in COS-7 cells, we have demonstrated that 3BP2 was predominantly phosphorylated on Tyr(174), Tyr(183), and Tyr(446) when it was coexpressed with Syk. An in vitro binding study revealed that phosphorylation of Tyr(446) by Syk was likely to create a binding site for the Lyn-SH2 domain in RBL-2H3 cells. In addition, proline-rich region of 3BP2 bound to the Lyn-SH3 domain. Conformational microscopic analysis showed that Lyn and 3BP2 are constitutively colocalized in RBL-2H3 cells. Overexpression of 3BP2 in RBL-2H3 cells resulted in an enhancement of Lyn autophosphorylation. These results suggest that the adaptor protein 3BP2 is a potential regulator of Lyn protein-tyrosine kinase as a ligand of its SH3/SH2 domains in FcepsilonRI-mediated signaling in mast cells.