DUAL ROLE OF THE TYROSINE ACTIVATION MOTIF OF THE IG-ALPHA PROTEIN DURING SIGNAL-TRANSDUCTION VIA THE B-CELL ANTIGEN RECEPTOR
DUAL ROLE OF THE TYROSINE ACTIVATION MOTIF OF THE IG-ALPHA PROTEIN DURING SIGNAL-TRANSDUCTION VIA THE B-CELL ANTIGEN RECEPTOR
复制标题
DOI：
10.1002/j.1460-2075.1994.tb06237.x
复制
发表时间：
1994-01-01
期刊：
影响因子：
11.4
通讯作者：
RETH, M
中科院分区：
文献类型：
--
作者：
FLASWINKEL, H;RETH, M
B细胞抗原受体（BCR）是一种多聚体蛋白复合物，由配体结合免疫球蛋白分子和Ig-α/β异二聚体组成，后者通过将受体偶联至蛋白酪氨酸激酶（PTK）介导细胞内信号传导。用编码突变的Ig-α的表达载体转染Ig-α缺陷型骨髓瘤细胞系J558 L μ m，使我们能够在BCR的背景下测试Ig-α胞质区中酪氨酸的功能。此外，我们在K46 B淋巴瘤细胞上表达Ig-α突变作为嵌合CD 8-Ig-α分子，并测试其在PTK活化和钙释放方面的信号传导能力。我们在这里表明，保守的酪氨酸残基在细胞质部分的Ig-cr有双重作用。首先，它们是信号诱导期间PTKs有效活化所必需的，其次，它们中的一个受到活化的src相关PTKs的磷酸化。酪氨酸磷酸化的Ig-α的胞质部分进行了讨论，作为一种可能的机制，耦合BCR SH 2域携带分子。
The B cell antigen receptor (BCR) is a multimeric protein complex consisting of the ligand binding immunoglobulin molecule and the Ig-alpha/beta heterodimer that mediates intracellular signalling by coupling the receptor to protein tyrosine kinases (PTKs). Transfection of the Ig-alpha deficient myeloma cell line J558L mu m with expression vectors coding for mutated Ig-alpha allowed us to test the function of the tyrosines in the cytoplasmic region of Ig-alpha in the context of the BCR. Furthermore we expressed Ig-alpha mutations as chimeric CD8-Ig-alpha molecules on K46 B lymphoma cells and tested their signalling capacity in terms of PTK activation and release of calcium. We show here that the conserved tyrosine residues in the cytoplasmic portion of Ig-cr have a dual role. First, they are required for efficient activation of PTKs during signal induction and second, one of them is subject to phosphorylation by activated src-related PTKs. Phosphorylation on tyrosine in the cytoplasmic portion of Ig-alpha is discussed as a possible mechanism to couple the BCR to SH2 domain-carrying molecules.