Wienands J, Freuler F, Baumann G
Max-Planck-Institut für Immunobiologie, Freiburg, Germany.
Int Immunol. 1995 Nov;7(11):1701-8. doi: 10.1093/intimm/7.11.1701.
The protein tyrosine kinase Syk plays an important role in signal transduction from the B cell antigen receptor and possibly also from the TCR. We have examined the binding specificity of Syk-derived SH2 domains in vitro and found that the tandem SH2 domains have two major ligands in activated Ramos B cells as well as in activated Jurkat T cells. The SH2-binding proteins in Ramos B cells were identified as the tyrosine-phosphorylated forms of the Ig alpha beta heterodimer and of CD22. Binding to the Ig alpha beta heterodimer seems to occur predominantly via Ig beta, indicating that the two receptor components might couple to distinct signaling pathways. In Jurkat T cells one of the SH2-binding proteins represents the tyrosine-phosphorylated TCR zeta chain. The identity of the second SH2 ligand, called HOSS, is not known. HOSS is discussed as a putative member of the receptor family characterized by the immunoreceptor tyrosine-based activation motif.
蛋白酪氨酸激酶Syk在B细胞抗原受体的信号转导中发挥重要作用，可能在TCR的信号转导中也发挥作用。我们在体外检测了Syk衍生的SH2结构域的结合特异性，发现串联SH2结构域在活化的Ramos B细胞以及活化的Jurkat T细胞中有两个主要配体。Ramos B细胞中的SH2结合蛋白被鉴定为Igαβ异二聚体和CD22的酪氨酸磷酸化形式。与Igαβ异二聚体的结合似乎主要通过Igβ发生，这表明两个受体组分可能与不同的信号通路偶联。在Jurkat T细胞中，一种SH2结合蛋白是酪氨酸磷酸化的TCRζ链。第二种SH2配体称为HOSS，其身份尚不清楚。HOSS被认为是基于免疫受体酪氨酸的活化基序所表征的受体家族的推定成员。
