Suzuki Y, Demoliere C, Kitamura D, Takeshita H, Deuschle U, Watanabe T
Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan.
J Immunol. 1997 Mar 15;158(6):2736-44.
Cross-linking of the Ag receptors on lymphocytes initiates activation of the receptor-coupled tyrosine kinases. HS1 is one of the substrates of these kinases and has been shown to transduce the signals for both clonal expansion and deletion in lymphoid cells. To gain further insight into the mechanism of action of HS1, we have tried to identify a protein that interacts with HS1 by yeast two-hybrid screening. The isolated cDNA, designated HAX-1, encodes a novel 35-kDa protein. The HAX-1 gene is expressed ubiquitously among tissues, and its protein is localized mainly in mitochondria, but also in endoplasmic reticulum and nuclear envelope in the cell. HS1/HAX-1 association is confirmed by coimmunoprecipitation of these proteins in the lysates of B lymphoma cells and COS-7 cells transfected with the corresponding cDNA expression vectors. Colocalization of these proteins in the cell is evident under confocal laser scanning microscope. Deletion mutant analysis of these proteins reveals that the association is mediated by the amino terminal region of HS1 and the carboxyl-terminal half of HAX-1. The potential role of the HAX-1/HS1 complex is discussed.
淋巴细胞上抗原受体的交联引发了受体偶联酪氨酸激酶的激活。HS1是这些激酶的底物之一，已被证明能在淋巴细胞中传导克隆扩增和缺失的信号。为了进一步深入了解HS1的作用机制，我们试图通过酵母双杂交筛选来鉴定一种与HS1相互作用的蛋白质。分离出的cDNA命名为HAX-1，编码一种新的35 kDa蛋白质。HAX-1基因在各组织中普遍表达，其蛋白质主要定位于线粒体，但也存在于细胞的内质网和核膜中。通过在转染了相应cDNA表达载体的B淋巴瘤细胞和COS-7细胞裂解物中对这些蛋白质进行共免疫沉淀，证实了HS1/HAX-1的结合。在共聚焦激光扫描显微镜下，这些蛋白质在细胞中的共定位很明显。对这些蛋白质的缺失突变分析表明，这种结合是由HS1的氨基末端区域和HAX-1的羧基末端介导的。讨论了HAX-1/HS1复合物的潜在作用。
