Alternatively spliced transcripts from the Drosophila eIF4E gene produce two different Cap-binding proteins.
Eukaryotic initiation factor 4E (eIF4E) is the subunit of eIF4F that binds to the cap structure at the 5' end of messenger RNA and is a critical component for the regulation of translation initiation. Using 7-methyl-GTP-Sepharose affinity chromatography, two distinct cap-binding proteins that migrate on SDS-polyacrylamide gel electrophoresis at approximately 35 kDa were purified from Drosophila adults. Peptide microsequence analysis indicated that these two proteins differ at their amino termini. Analysis of a set of cDNA clones encoding eIF4E led to the conclusion that the two different protein isoforms, which we term eIF4EI and eIF4EII, result from three alternatively spliced transcripts from a single eIF4E gene, which maps to region 67A8-B2 on polytene chromosomes. The three eIF4E transcripts also vary greatly in the lengths of their 5'-UTRs, suggesting the possibility of complex translational control of expression of the two eIF4E isoforms.
Lavoie
C A
CA
Department of Biology, McGill University, Montréal, Québec, Canada H3A 1B1.
Lachance
P E
PE
Sonenberg
N
N
Lasko
P
P
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism*; D039561:Eukaryotic Initiation Factor-4E; D005091:Exons; D017344:Genes, Insect; D017403:In Situ Hybridization; D007438:Introns; D051379:Mice; D008969:Molecular Sequence Data; D010448:Peptide Initiation Factors / Q000096:biosynthesis* / Q000235:genetics* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D039381:RNA Cap-Binding Proteins; D016601:RNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D014908:Triticum / Q000235:genetics
D017931:DNA Primers; D039561:Eukaryotic Initiation Factor-4E; D010448:Peptide Initiation Factors; D039381:RNA Cap-Binding Proteins; D016601:RNA-Binding Proteins