Aoki Y, Kim Y T, Stillwell R, Kim T J, Pillai S
Cancer Center of Massachusetts General Hospital, Boston 02129, USA.
J Biol Chem. 1995 Jun 30;270(26):15658-63. doi: 10.1074/jbc.270.26.15658.
Src family kinases (Lyn, Fyn, Lck, and Blk) and Syk, a tandem SH2 domain containing tyrosine kinase, have been demonstrated to be associated with the antigen receptor in B cells. Both of these categories of tyrosine kinases are presumed to be critical players in the process of antigen-mediated signal transduction. Cross-linking of membrane immunoglobulin on the surface of B cells leads to the activation of Lyn, Fyn, and Blk, which presumably associate with the cytoplasmic tails of the membrane immunoglobulin-associated Ig alpha/beta heterodimer. Receptor ligation also leads to the tyrosine phosphorylation and catalytic activation of Syk, but the mechanism of association of this kinase with the antigen receptor remains to be established. A number of phosphoproteins that can associate with the SH2 domains of Blk, Lyn, and Fyn have been described in activated B cells. We demonstrate here that Syk is one of the proteins in the lysates of activated B cells which bind to the SH2 domains of Src family kinases. Syk binds directly to the SH2 domain of Blk and complexes in vivo with Lyn and Blk in activated B cells.
Src家族激酶（Lyn、Fyn、Lck和Blk）以及Syk（一种含有串联SH2结构域的酪氨酸激酶）已被证明与B细胞中的抗原受体相关。这两类酪氨酸激酶都被认为是抗原介导的信号转导过程中的关键参与者。B细胞表面膜免疫球蛋白的交联导致Lyn、Fyn和Blk的激活，它们可能与膜免疫球蛋白相关的Igα/β异二聚体的胞质尾部结合。受体连接还导致Syk的酪氨酸磷酸化和催化激活，但其与抗原受体的结合机制仍有待确定。在活化的B细胞中已描述了许多可与Blk、Lyn和Fyn的SH2结构域结合的磷蛋白。我们在此证明，Syk是活化B细胞裂解物中与Src家族激酶的SH2结构域结合的蛋白之一。Syk直接与Blk的SH2结构域结合，并在体内与活化B细胞中的Lyn和Blk形成复合物。
