Characterization of two evolutionarily conserved, alternatively spliced nuclear phosphoproteins, NFAR-1 and -2, that function in mRNA processing and interact with the double-stranded RNA-dependent protein kinase, PKR.
We report here the isolation and characterization of two proteins, NFAR-1 and -2, which were isolated through their ability to interact with the dsRNA-dependent protein kinase, PKR. The NFAR proteins, of 90 and 110 kDa, are derived from a single gene through alternative splicing and are evolutionarily conserved nuclear phosphoproteins ... that interact with double-stranded RNA. Both NFAR-1 and -2 are phosphorylated by PKR, reciprocally co-immunoprecipitate with PKR, and colocalize with the kinase in a diffuse nuclear pattern within the cell. Transfection studies indicate that the NFARs regulate gene expression at the level of transcription, probably during the processing of pre-mRNAs, an activity that was increased in fibroblasts lacking PKR. Subsequent functional analyses indicated that amino acids important for NFAR's activity were localized to the C terminus of the protein, a region that was found to specifically interact with FUS and SMN, proteins also known as regulators of RNA processing. Accordingly, both NFARs were found to associate with both pre-mRNAs and spliced mRNAs in post-transcriptional studies, similar to the known splicing factor ASF/SF-2. Collectively, our data indicate that the NFARs may facilitate double-stranded RNA-regulated gene expression at the level of post-transcription and possibly contribute to host defense-related mechanisms in the cell.
Mesh Terms:
Alternative Splicing, Amino Acid Sequence, Animals, Base Sequence, COS Cells, Cell Nucleus, DNA Primers, DNA, Complementary, Evolution, Molecular, Molecular Sequence Data, Nuclear Factor 90 Proteins, Phosphoproteins, Precipitin Tests, Protein Isoforms, RNA Processing, Post-Transcriptional, RNA, Messenger, RNA-Binding Proteins, Reverse Transcriptase Polymerase Chain Reaction, Sequence Homology, Amino Acid, Substrate Specificity, eIF-2 Kinase
Alternative Splicing, Amino Acid Sequence, Animals, Base Sequence, COS Cells, Cell Nucleus, DNA Primers, DNA, Complementary, Evolution, Molecular, Molecular Sequence Data, Nuclear Factor 90 Proteins, Phosphoproteins, Precipitin Tests, Protein Isoforms, RNA Processing, Post-Transcriptional, RNA, Messenger, RNA-Binding Proteins, Reverse Transcriptase Polymerase Chain Reaction, Sequence Homology, Amino Acid, Substrate Specificity, eIF-2 Kinase
J. Biol. Chem.
Date: Aug. 24, 2001
PubMed ID: 11438536
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