Growth factor receptor bound protein 7 (Grb7) is a mammalian adaptor protein participating in signaling pathways implicated in cell migration, metastatic invasion, cell proliferation and tumor-associated angiogenesis. We expressed tagged versions of wild type Grb7 and the mutant Grb7Δ, lacking its calmodulin-binding domain (CaM-BD), in human embryonic kidney (HEK) 293 cells and rat glioma C6 cells to identify novel binding partners using shot-gun proteomics. Among the new identified proteins, we validated the ubiquitin-ligase Nedd4 (neural precursor cell expressed developmentally down-regulated protein 4), the heat-shock protein Hsc70/HSPA8 (heat shock cognate protein 70) and the cell cycle regulatory protein caprin-1 (cytoplasmic activation/proliferation-associated protein 1) in rat glioma C6 cells. Our results suggest a role of Grb7 in pathways where these proteins are implicated. These include protein trafficking and degradation, stress-response, chaperone-mediated autophagy, apoptosis and cell proliferation.

中文翻译：

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野生型Grb7和缺少其钙调蛋白结合域的突变体的伴侣。

生长因子受体结合蛋白7（Grb7）是一种哺乳动物衔接蛋白，参与与细胞迁移，转移性侵袭，细胞增殖和肿瘤相关的血管生成有关的信号传导途径。我们在人胚胎肾（HEK）293细胞和大鼠神经胶质瘤C6细胞中表达了野生型Grb7和突变型Grb7Δ（缺少其钙调蛋白结合域）（CaM-BD）的标记版本，以使用shot弹枪蛋白质组学鉴定新型结合伴侣。在新鉴定出的蛋白质中，我们验证了泛素连接酶Nedd4（神经前体细胞表达被发育性下调的蛋白质4），热休克蛋白Hsc70 / HSPA8（热休克同源蛋白70）和细胞周期调控蛋白caprin-1大鼠脑胶质瘤C6细胞中的“胞浆激活/增殖相关蛋白1”（胞质激活/增殖相关蛋白1）。我们的结果表明，Grb7在涉及这些蛋白的途径中发挥了作用。这些包括蛋白质运输和降解，应激反应，伴侣介导的自噬，细胞凋亡和细胞增殖。