Ren R, Ye Z S, Baltimore D
Rockefeller University, New York, New York 10021.
Genes Dev. 1994 Apr 1;8(7):783-95. doi: 10.1101/gad.8.7.783.
To understand the normal and oncogenic functions of the protein-tyrosine kinase Abl, the yeast two-hybrid system has been used for identifying proteins that interact with it. One interacting protein is Crk-I, an SH3/SH2-containing adapter protein that was originally identified as the oncogenic element in the avian sarcoma virus CT10. Direct interaction between the Crk-I SH3 and Abl at novel, approximately 10 amino acid sites just carboxy-terminal to the Abl kinase domain occurs in vitro and in mammalian cells. There is a nearby site specific for binding another adapter, Nck, and these sites also bind Grb-2. When bound to Abl, Crk-I was phosphorylated on tyrosine. Thus, the SH3-binding sites on Abl serve as substrate recognition sites for the relatively nonspecific kinase of Abl. In Crk-I-transformed cells, Crk-I associates with endogenous c-Abl and is phosphorylated on tyrosine. The association of Crk and Abl suggests that Abl could play a role in v-Crk and Crk-I transformation and that normal Abl function may be partly mediated through bound adapter molecules.
为了解蛋白质酪氨酸激酶Abl的正常功能和致癌功能，酵母双杂交系统已被用于鉴定与它相互作用的蛋白质。一种相互作用蛋白是Crk-I，它是一种含SH3/SH2的衔接蛋白，最初被鉴定为禽肉瘤病毒CT10中的致癌元件。Crk-I的SH3与Abl在Abl激酶结构域羧基末端附近新发现的约10个氨基酸位点处直接相互作用，这种相互作用在体外和哺乳动物细胞中均会发生。附近还有一个特异性结合另一种衔接蛋白Nck的位点，这些位点也能结合Grb-2。当与Abl结合时，Crk-I的酪氨酸会被磷酸化。因此，Abl上的SH3结合位点充当了Abl相对非特异性激酶的底物识别位点。在Crk-I转化的细胞中，Crk-I与内源性c-Abl结合，并在酪氨酸上被磷酸化。Crk与Abl的结合表明，Abl可能在v-Crk和Crk-I转化中发挥作用，而且正常的Abl功能可能部分是通过结合的衔接分子介导的。
