Ribon V, Saltiel A R
Department of Physiology, University of Michigan School of Medicine, Ann Arbor, 48109, USA.
J Biol Chem. 1996 Mar 29;271(13):7375-80. doi: 10.1074/jbc.271.13.7375.
The cellular homologs of the v-Crk oncogene product consist primarily of Src homology region 2 (SH2) and 3 (SH3) domains. v-Crk overexpression causes cell transformation and elevation of tyrosine phosphorylation in fibroblasts and accelerates differentiation of PC-12 cells in response to nerve growth factor (NGF). To further explore the role of Crk in NGF-induced PC-12 cell differentiation, we found that both NGF and epidermal growth factor stimulate the tyrosine phosphorylation of endogenous Crk II. Moreover, hormone stimulation enhanced the specific association of Crk proteins with the tyrosine-phosphorylated p130Cas, the major phosphotyrosine-containing protein in cells transformed with v-Crk. This interaction is mediated by the SH2 domain of Crk and can be inhibited with a phosphopeptide containing the Crk-SH2 binding motif. Furthermore, the Crk-SH2 domain binds tyrosine-phosphorylated paxillin, a cytoskeletal protein, following treatment of PC-12 cells with NGF or epidermal growth factor. These data suggest that Crk functions in a number of signaling processes in PC-12 cells.
v-Crk癌基因产物的细胞同源物主要由Src同源区域2（SH2）和3（SH3）结构域组成。v-Crk的过表达导致成纤维细胞中的细胞转化和酪氨酸磷酸化水平升高，并加速PC-12细胞对神经生长因子（NGF）的分化响应。为了进一步探究Crk在NGF诱导的PC-12细胞分化中的作用，我们发现NGF和表皮生长因子均能刺激内源性Crk II的酪氨酸磷酸化。此外，激素刺激增强了Crk蛋白与酪氨酸磷酸化的p130Cas的特异性结合，p130Cas是用v-Crk转化的细胞中主要的含磷酸酪氨酸蛋白。这种相互作用由Crk的SH2结构域介导，并且可以被含有Crk-SH2结合基序的磷酸肽抑制。此外，在用NGF或表皮生长因子处理PC-12细胞后，Crk-SH2结构域与酪氨酸磷酸化的桩蛋白（一种细胞骨架蛋白）结合。这些数据表明Crk在PC-12细胞的许多信号传导过程中发挥作用。
