Characterization of the cell membrane-associated products of the Neuregulin 4 gene
Characterization of the cell membrane-associated products of the Neuregulin 4 gene
复制标题
DOI：
10.1038/sj.onc.1210689
复制
发表时间：
2008-01-24
期刊：
影响因子：
8
通讯作者：
Gullick, W. J.
中科院分区：
文献类型：
--
作者：
Hayes, N. V. L.;Newsam, R. J.;Gullick, W. J.
NRG4 基因是编码一类表皮生长因子的四个基因家族的成员。据报道，该基因表达一种此处指定为 NRG4A1 的蛋白质。我们在这里描述了 NRG4 基因的一种新剪接变体 NRG4A2，它编码含有预测的 I 型 PDZ 结合肽的 C 末端区域。 NRG4A1 和 NRG4A2 均显示在细胞表面表达，正如预测的跨膜序列的存在所预期的那样，并且在胞外结构域中的单个 N 连接糖基化位点处进行了修饰。在蛋白酶体抑制剂 MG-132 存在的情况下，两种蛋白质的表达均显着稳定，表明它们通常会被该系统降解。广谱基质金属蛋白酶抑制剂加拉丁 (GM 6001) 抑制两种同种型的 N 末端裂解。在细胞培养基中检测到糖基化、分泌形式的 NRG4A1，该形式在两项测定中显示出生物活性：HER4 受体的磷酸化和稳定表达 HER4 的 PC-12 细胞中神经突形成的刺激。绿色荧光蛋白标记蛋白的转染和表达以及特异性抗肽抗体的免疫荧光染色表明NRG4A1定位于膜褶边，而NRG4A2具有更点状的膜分布。
The NRG4 gene is a member of a family of four genes that encode a class of epidermal growth factors. This gene has been reported to express a protein designated here as NRG4A1. We describe here a novel splice variant of the NRG4 gene, NRG4A2, which encodes a C-terminal region containing a predicted type I PDZ-binding peptide. Both NRG4A1 and NRG4A2 were shown to be expressed on the cell surface, as expected by the presence of a predicted transmembrane sequence, and were modified at a single N-linked glycosylation site in the extracellular domain. Significant stabilization of expression of both proteins was seen in the presence of the proteosome inhibitor MG-132 suggesting that they are normally degraded by this system. N-terminal cleavage was inhibited in both isotypes by the broad-spectrum matrix metalloproteinase inhibitor, galardin (GM 6001). A glycosylated, secreted form of NRG4A1 was detected in the cell medium which showed biological activity in two assays, phosphorylation of the HER4 receptor and stimulation of neurite formation in PC-12 cells stably expressing HER4. Transfection and expression of green fluorescent protein-tagged proteins and immunofluorescent staining with specific anti-peptide antibodies showed that NRG4A1 is localized to membrane ruffles, while NRG4A2 has a more punctate membrane distribution.