Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The translational regulation of ferritin expression currently represents the only well characterized example for eukaryotic translational control by high affinity interactions between a specific cytoplasmic protein, iron regulatory factor [IRF], and an mRNA-binding site, the iron-responsive element [IRE], located in the 5' untranslated region [UTR] of ferritin mRNAs. To elucidate whether IRE/IRF may represent the first physiological example of a more general mechanism for mRNA-specific translational control, high affinity RNA-binding sites for the bacteriophage MS2 coat protein or the spliceosomal protein U1A were introduced into the 5' UTR of capped chloramphenicol acetyltransferase [CAT] transcripts. In the absence of these RNA-binding proteins, CAT mRNA was efficiently translated. Addition of purified MS2 coat protein or U1A caused a specific, dose-dependent repression of CAT biosynthesis in rabbit reticulocyte and wheat germ in vitro translation systems. The translational blockage imposed by the RNA/protein complex was reversible and did not alter the stability of the repressed mRNAs. Translational repression caused by binding of U1A or MS2 proteins to their target mRNAs is shown to be position-dependent in vitro. Thus, mRNA/protein complexes without an a priori role in eukaryotic mRNA translation function as translational effectors with characteristics resembling those of IRE/IRF.
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PMID:Bacteriophage and spliceosomal proteins function as position-dependent cis/trans repressors of mRNA translation in vitro. 145 20

In previous studies, we showed that acute administration of iron to intact rats or to rat hepatoma cells in culture induces synthesis of the iron-storage protein ferritin by activating translation of inactive cytoplasmic ferritin mRNAs for both the heavy (H) and the light (L) subunits. In the course of activation, these ferritin mRNAs are recruited onto polysomes. To elucidate the structural features of these mRNAs involved in the translational response to iron, a chimera was constructed from the 5' and 3' untranslated regions (UTRs) of ferritin L subunit mRNA fused to the reading frame of the mRNA of bacterial chloramphenicol acetyltransferase (CAT). This chimera and deletion constructs derived from it were introduced into a rat hepatoma cell line by retrovirus-mediated gene transfer. The complete chimera showed increased CAT activity in response to iron enrichment of the medium, whereas deletion of the first 67 nucleotides of the 5' UTR, which contain a highly conserved sequence, caused loss of regulation by iron. Whereas cis-acting sequences located in the 5' flanking regions of many genes have been repeatedly implicated in modulating their transcriptional expression, we report here a specific regulatory translational sequence found within the 5' UTR of a eukaryotic mRNA.
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PMID:Iron regulates ferritin mRNA translation through a segment of its 5' untranslated region. 347 2