Nuclear factor-90 of activated T-cells: A double-stranded RNA-binding protein and substrate for the double-stranded RNA-dependent protein kinase, PKR.

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 Mr = 90 000 (NF90) and Mr = 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.
Mesh Terms:
Amino Acid Sequence, Consensus Sequence, DNA-Binding Proteins, Hela Cells, Humans, Jurkat Cells, Lymphocyte Activation, Molecular Sequence Data, NFATC Transcription Factors, Nuclear Factor 45 Protein, Nuclear Factor 90 Proteins, Nuclear Proteins, Phosphorylation, RNA-Binding Proteins, Sequence Homology, Amino Acid, T-Lymphocytes, Transcription Factors, eIF-2 Kinase
Biochemistry
Date: May. 11, 1999
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