Nuclear factor 90 is a substrate and regulator of the eukaryotic initiation factor 2 kinase double-stranded RNA-activated protein kinase.

Nuclear factor 90 (NF90) is a member of an expanding family of double-stranded (ds) RNA-binding proteins thought to be involved in gene expression. Originally identified in complex with nuclear factor 45 (NF45) as a sequence-specific DNA-binding protein, NF90 contains two double stranded RNA-binding motifs (dsRBMs) and interacts with highly structured ...
RNAs as well as the dsRNA-activated protein kinase, PKR. In this report, we characterize the biochemical interactions between these two dsRBM containing proteins. NF90 binds to PKR through two independent mechanisms: an RNA-independent interaction occurs between the N terminus of NF90 and the C-terminal region of PKR, and an RNA-dependent interaction is mediated by the dsRBMs of the two proteins. Co-immunoprecipitation analysis demonstrates that NF90, NF45, and PKR form a complex in both nuclear and cytosolic extracts, and both proteins serve as substrates for PKR in vitro. NF90 is phosphorylated by PKR in its RNA-binding domain, and this reaction is partially blocked by the NF90 N-terminal region. The C-terminal region also inhibits PKR function, probably through competitive binding to dsRNA. A model for NF90-PKR interactions is proposed.
Mesh Terms:
Animals, Binding Sites, Cell Nucleus, Cytosol, DNA-Binding Proteins, Kinetics, Models, Molecular, NFATC Transcription Factors, Nuclear Factor 45 Protein, Nuclear Factor 90 Proteins, Nuclear Proteins, Nucleic Acid Conformation, Protein Conformation, RNA, RNA, Double-Stranded, RNA-Binding Proteins, Recombinant Fusion Proteins, Sequence Deletion, Substrate Specificity, Transcription Factors, eIF-2 Kinase
J. Biol. Chem.
Date: Aug. 31, 2001
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