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Functional characterization of five eIF4E isoforms in Caenorhabditis elegans
Functional characterization of five eIF4E isoforms in Caenorhabditis elegans.
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Recognition of the 5'-cap structure of mRNA by eIF4E is a critical step in the recruitment of most mRNAs to the ribosome. In Caenorhabditis elegans, approximately 70% of mRNAs contain an unusual 2,2,7-trimethylguanosine cap structure as a result of trans-splicing onto the 5' end of the pre-mRNA. The characterization of three eIF4E isoforms in C. elegans (IFE-1, IFE-2, and IFE-3) was reported previously. The present study describes two more eIF4E isoforms expressed in C. elegans, IFE-4 and IFE-5. We analyzed the requirement of each isoform for viability by RNA interference. IFE-3, the most closely related to mammalian eIF4E-1, binds only 7-methylguanosine caps and is essential for viability. In contrast, three closely related isoforms (IFE-1, IFE-2, and IFE-5) bind 2,2, 7-trimethylguanosine caps and are partially redundant, but at least one functional isoform is required for viability. IFE-4, which binds only 7-methylguanosine caps, is most closely related to an unusual eIF4E isoform found in plants (nCBP) and mammals (4E-HP) and is not essential for viability in any combination of IFE knockout. ife-2, ife-3, ife-4, and ife-5 mRNAs are themselves trans-spliced to SL1 spliced leaders. ife-1 mRNA is trans-spliced to an SL2 leader, indicating that its gene resides in a downstream position of an operon.
Keiper BD, Lamphear BJ, Deshpande AM, Jankowska-Anyszka M, Aamodt EJ, Blumenthal T, Rhoads RE
The Journal of biological chemistry
2000-04-07 00:00
275
14
10590-6
Amino Acid Sequence,Animals,Binding Sites,Caenorhabditis elegans,Cloning, Molecular,Embryo, Nonmammalian,Eukaryotic Initiation Factor-4E,Humans,Molecular Sequence Data,Oligodeoxyribonucleotides,Peptide Initiation Factors,Phylogeny,Protein Isoforms,RNA Caps,Recombinant Proteins,Reverse Transcriptase Polymerase Chain Reaction,Sequence Alignment,Sequence Homology, Amino Acid,Eukaryotic Initiation Factor-4E,Oligodeoxyribonucleotides,Peptide Initiation Factors,Protein Isoforms,RNA Caps,Recombinant Proteins
Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130-3932, USA
J. Biol. Chem.
NIGMS GM20818, NIGMS GM42432
0021-9258
37
True
10744754
