Nuclear factor-90 of activated T-cells: A double-stranded RNA-binding protein and substrate for the double-stranded RNA-dependent protein kinase, PKR
Nuclear factor-90 of activated T-cells: A double-stranded RNA-binding protein and substrate for the double-stranded RNA-dependent protein kinase, PKR
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DOI：
10.1021/bi982410u
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发表时间：
1999-05-11
期刊：
影响因子：
2.9
通讯作者：
Jacobs, BL
中科院分区：
文献类型：
--
作者：
Langland, JO;Kao, PN;Jacobs, BL
NFAT转录因子通过诱导包括白细胞介素-2（IL-2）在内的立即早期T细胞特异性基因，在启动T细胞活化中发挥核心作用。NFAT转录因子与IL-2增强子中称为抗原受体应答元件2（ARRE-2）的序列结合。已经分离出多种表现出ARRE-2结合活性的蛋白质，包括来自刺激的T细胞核提取物的由M-r = 90 000（NF 90）和M-r = 45 000（NF 45）亚基组成的异二聚体。这种异源二聚体的亚基已经被克隆，并且发现NF 90编码含有两个结构域的蛋白质，所述两个结构域被预测形成能够结合双链RNA的基序。使用体外翻译的多肽，我们已经证明NF 90特异性结合双链RNA。此外，NF 90以双链RNA依赖的方式被磷酸化，可能是通过干扰素诱导的双链RNA依赖的蛋白激酶PKR。发现NF 90蛋白不仅在T细胞中表达，而且在非免疫HeLa细胞中表达。在HeLa细胞中，蛋白质几乎完全定位于细胞裂解物的核糖体盐洗涤部分。
NFAT transcription factors play a central role in initiating T-cell activation through the induction of immediate-early T-cell specific genes including interleukin-2 (IL-2). NFAT transcription factors bind to a sequence in the IL-2 enhancer known as the antigen receptor response element 2 (ARRE-2). Multiple proteins exhibiting ARRE-2 binding activity have been isolated, including a heterodimer from stimulated T-cell nuclear extracts consisting of M-r = 90 000 (NF90) and M-r = 45 000 (NF45) subunits. The subunits of this heterodimer have been cloned, and NF90 was found to encode a protein containing two domains that are predicted to form motifs capable of binding to double-stranded RNA. Using in vitro translated polypeptides, we have demonstrated that NF90 specifically binds to double-stranded RNA. Furthermore, NF90 was phosphorylated in a double-stranded RNA-dependent manner likely by the interferon-induced, double-stranded RNA-dependent protein kinase, PKR. The NF90 protein was found to be expressed not only in T-cells, but also in nonimmune HeLa cells. In HeLa cells, the protein was almost exclusively localized to the ribosome salt wash fraction of cell lysates.