Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The adenovirus tripartite leader (TPT) 5' untranslated region (5'UTR) allows translation in poliovirus-infected cells, in which the p220 subunit of eukaryotic initiation factor 4F is degraded. This p220-independent translation was investigated by measuring in vitro translation in a reticulocyte lysate of a reporter gene, chloramphenicol acetyltransferase, coupled to the TPT 5'UTR. The p220 subunit was degraded by translation of a foot-and-mouth-disease L-protease construct. Surprisingly, the TPT 5'UTR was dependent on intact p220, as are other naturally capped mRNA species. Translation of encephalomyocarditis virus RNA was p220 independent, as expected from its ability to support internal, cap-independent initiation. In vitro protein-synthesis experiments with purified initiation factors confirmed the dependence of TPT mRNA translation on eukaryotic initiation factor 4F. The relationship between adenovirus TPT-5'UTR-directed translation and poliovirus-induced host cell shut-off is discussed.
...
PMID:Dependence of the adenovirus tripartite leader on the p220 subunit of eukaryotic initiation factor 4F during in vitro translation. Effect of p220 cleavage by foot-and-mouth-disease-virus L-protease on in vitro translation. 132 14

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.
...
PMID:Bacteriophage and spliceosomal proteins function as position-dependent cis/trans repressors of mRNA translation in vitro. 145 20

A full length human androgen receptor (hAR) cDNA was constructed from cDNA and genomic clones. Structurally the 10.6-kilobase (kb) hAR cDNA consists of a long 5'-untranslated region (5'-UTR, 1.1 kb), a previously described open reading frame (ORF, 2.7 kb) (Trapman, J., Klaassen, P., Kuiper, G. G. J. M., van der Korput, J. A. G. M., Faber, P. W., van Rooij, H. C. J., Geurts van Kessel, A., Voorhorst, M. M., Mulder, E., and Brinkmann, A. O. (1988) Biochem. Biophys. Res. Commun. 153, 241-248; Faber, P. W., Kuiper, G. G. J. M., van Rooij, H. C. J., van der Korput, J. A. G. M., Brinkmann, A. O., and Trapman, J. (1989) Mol. Cell. Endocrinol. 61, 257-262), and a very long 3'-untranslated region (3'-UTR, 6.8 kb). The complete 5'- and 3'-UTRs were found to be encoded by the previously reported first and eight protein coding exons of the hAR gene, respectively (Kuiper, G. G. J. M., Faber, P. W., van Rooij, H. C. J., van der Korput, J. A. G. M., Ris-Stalpers, C., Klaassen, P., Trapman, J., and Brinkmann, A. O. (1989) J. Mol. Endocrinol. 2, R1-R4). Two major sites of transcription initiation were identified in a 13-base pair region. DNA fragments spanning these transcription initiation sites conferred promoter activity upon a promoterless chloramphenicol acetyltransferase reporter gene construct. Two equally effective, functional polyadenylation signals (ATTAAA and CATAAA) at a mutual distance of 221 base pairs were detected. The ATTAAA hexamer sequence gave rise to multiple sites of poly(A) addition, whereas only one position was used following the CATAAA hexamer. In LNCaP prostatic carcinoma cells an alternatively spliced hAR mRNA species was identified which lacks 3 kb of the 3'-UTR.
...
PMID:Characterization of the human androgen receptor transcription unit. 171 Feb 13

Expression of the two bovine papillomavirus type 1 (BPV-1) late genes, L1 and L2, coding for the two capsid proteins, is limited to terminally differentiated keratinocytes in bovine fibropapillomas. This pattern of expression is determined both by the activity of the late promoter and by the inhibition of late region expression in less well differentiated cells. Inhibition of L1 and L2 mRNA production in nonpermissive cells must occur since the late region potentially could be transcribed from early region promoters. Nuclear runoff analysis of the late region has demonstrated that up to 95% of transcripts which are initiated in the early region in nonpermissive cells terminate within the late region upstream of the late polyadenylation site (C. C. Baker and J. Noe, J. Virol. 63:3529-3534, 1989). However, very few of the primary transcripts which include the late polyadenylation site are processed into mRNA. In this study, we have used expression vectors to characterize an inhibitory element active in nonpermissive cells which is located in the late 3' untranslated region (3'UTR). While the late polyadenylation site is functional in these cells, a 53-bp element in the late 3'UTR reduces levels of polyadenylated cytoplasmic RNA. This element inhibited chloramphenicol acetyltransferase (CAT) expression 6- to 10-fold when cloned in the sense orientation into the 3'UTR of a CAT expression vector. No block to expression was seen when the fragment was cloned immediately downstream of the poly(A) site, in an intron upstream of the CAT coding sequence, or in an antisense orientation in the 3'UTR. When the same fragment was deleted from a BPV-1 L1 expression vector, a sixfold increase in mRNA levels was seen. Actinomycin D chase experiments using BPV-1 L1 expression vectors indicated that the element does not destabilize cytoplasmic polyadenylated RNA. Therefore, the element must act before the mature mRNA reaches the cytoplasm. The data presented are consistent with effects on nuclear stability and/or inhibition of polyadenylation or nuclear transport.
...
PMID:An element in the bovine papillomavirus late 3' untranslated region reduces polyadenylated cytoplasmic RNA levels. 171 10

The tumor necrosis factor (TNF) promoter and 3'-untranslated region (3'-UTR) each contain sequence elements that mediate a response to bacterial endotoxin. Although the promoter contains sequences that permit augmented TNF gene transcription in response to LPS, the 3'-UTR contains sequences that normally confer translational repression, but which allow "derepression" to occur after cell contact with endotoxin. We now show that both genetic elements act in concert during activation of TNF gene expression in macrophages. In order to do so, we have made use of chloramphenicol acetyltransferase reporter constructs in which the TNF promoter and 3'-UTR are represented either independently or in combination with one another. Suppression of chloramphenicol acetyltransferase and TNF mRNA synthesis, observed after treatment of the macrophages with dexamethasone, 2-aminopurine, pentoxifylline, or dibutyryl cAMP, has also been studied in detail. Each class of inhibitor suppresses TNF biosynthesis through a separate mechanism. Interestingly, suppression by pentoxifylline is manifested partly (but not entirely) at the level of transcription, and depends upon the presence of both the TNF promoter and 3'-UTR. The data suggest that other sequences within the TNF gene could also be required for the full effect of pentoxifylline, which may act to prevent processing of the primary transcript. The suppressive effect of dexamethasone is manifested both at the level of transcription and at the level of translation, and is mediated both by sequences present in the TNF promoter and by sequences present in the 3'-UTR. Suppression by 2-aminopurine is solely dependent upon promoter sequences.
...
PMID:Interactive effects of the tumor necrosis factor promoter and 3'-untranslated regions. 184 73

Phorbol esters (TPA) and concanavalin A (ConA) are known to induce granulocyte-macrophage colony-stimulating factor (GM-CSF) production in murine thymoma EL-4 cells by mRNA stabilization. The role of the 3'-untranslated region (3'-UTR) in GM-CSF mRNA stabilization induced by TPA and ConA in EL-4 cells was examined by transfection studies using chloramphenicol acetyltransferase (CAT) constructions. The GM-CSF 3'-UTR contains a 63-nucleotide region at its 3' end with repeating ATTTA motifs which is responsible for mRNA degradation in a variety of cell types (Shaw, G., and Kamen, R. (1986) Cell 46, 659-666). We produced constructs containing most of the GM-CSF 3'-UTR (303 nucleotides, pRSV-CATgm) or the 3'-terminal AT-rich region (116 nucleotides, pRSV-CATau) and measured CAT enzyme activity and CAT mRNA after transient transfection into EL-4 and NIH 3T3 cells. Low levels of CAT activity were seen in both cells with either plasmid compared with levels of CAT activity obtained with pRSV-CAT. TPA treatment caused an approximately 10-fold increase in CAT activity and mRNA in EL-4 cells transfected with pRSV-CATgm. No increases were seen in EL-4 cells transfected with pRSV-CATau or pRSV-CAT. No response to TPA was detected in transfected NIH 3T3 cells, indicating that the response to TPA is relatively cell-specific. There was no increase in CAT activity after ConA treatment in EL-4 or NIH 3T3 cells transfected with any of the constructs suggesting that the GM-CSF 3'-UTR lacks elements that can respond alone to ConA. Nuclear run-on and actinomycin D chase experiments in EL-4 cells showed that TPA induces CAT activity via mRNA stabilization. By linker-substitution mutagenesis we show that TPA inducibility depends on a 60-nucleotide region of the 3'-UTR whose 5' end is located 160 nucleotides upstream of the 5' end of the AU-rich region.
...
PMID:Identification of sequences within the murine granulocyte-macrophage colony-stimulating factor mRNA 3'-untranslated region that mediate mRNA stabilization induced by mitogen treatment of EL-4 thymoma cells. 191 35

A 593 nucleotide fragment of the 5' leader of encephalomyocarditis virus RNA (EMCV-RNA) was linked to the SP6 promoter and inserted upstream of the reporter gene chloramphenicol acetyltransferase (CAT). The presence of the 5'-UTR of EMCV-RNA in the RNA transcripts, made in vitro with the SP6 polymerase, resulted in a strong translational enhancement when tested in the micrococcal nuclease-treated reticulocyte lysate. The transcripts were equally active with or without a 5' methylated capstructure as expected, since EMCV-RNA is one of the mRNAs capable of internal initiation. We searched for a signal in the 5' leader that allows the 43S preinitiation complex to bind internally and localized a hairpin containing a unique nucleotide sequence, CUUUA, present in a domain conserved among cardio- and aphtoviral RNAs. Replacing this sequence into AGCU resulted in a 50% loss of translational activity. A second mutation involving a U-G change in the stem of that hairpin resulted in an almost complete loss of initiation.
...
PMID:An initiation signal in the 5' untranslated leader sequence of encephalomyocarditis virus RNA. 216 87

The 3' untranslated tail region (3'-UTR) of the cDNA of bovine interleukin 2 (bIL-2) acts as a lymphoid cell-specific gene regulatory element in vivo when ligated to the 3' end of the "marker" bacterial gene coding for chloramphenicol acetyltransferase (CAT) and the hybrid fusion gene is introduced into bovine lymphoid cells by transfection. Evidence is also presented that the 3'-UTR with its conserved (TATT)n motif probably has multiple functions in lymphoid cells operating both at the chromosomal level, where the sequence may be involved in the specific binding of the nonhistone chromatin high mobility group protein HMG-I, and at the RNA level, where the conserved sequence is involved in selective posttranscriptional mRNA degradation by a lymphocyte-specific nuclease(s). These results suggest a complex in vivo role for the 3'-UTR of bIL-2 cDNA and the conserved (TATT)n sequences found within it. They also offer a plausible explanation for the high degree of conservation of similar A + T-rich sequences in the 3'-UTRs of many of the other immune-response and growth-regulatory genes of mammals.
...
PMID:Posttranscriptional gene regulation and specific binding of the nonhistone protein HMG-I by the 3' untranslated region of bovine interleukin 2 cDNA. 349 64

The role of the 3' untranslated region (3'UTR) in the replication of enteroviruses has been studied with a series of mutants derived from either poliovirus type 3 (PV3) or a PV3 replicon containing the reporter gene chloramphenicol acetyltransferase. Replication was observed when the PV3 3'UTR was replaced with that of either coxsackie B4 virus, human rhinovirus 14 (HRV14), bovine enterovirus, or hepatitis A virus, despite the lack of sequence and secondary structure homology of the 3'UTRs of these viruses. The levels of replication observed for recombinants containing the 3'UTRs of hepatitis A virus and bovine enterovirus were lower than those for PV3 and the other recombinants. Extensive site-directed mutagenesis of the single stem-loop structure formed by the HRV14 3'UTR indicated the importance of (i) the loop sequence, (ii) the stability of the stem, and (iii) the location of the stem immediately upstream of the poly(A) tail. The role of a 4-bp motif at the base of the HRV14 stem, highly conserved among rhinoviruses, was examined by site-directed mutagenesis of individual base pairs. This analysis did not pinpoint a particular base pair as crucial for function. The requirement for immediate adjacent positioning of the open reading frame and the 3'UTR was examined by insertion of a 1.1-kb heterologous sequence. A replicon containing this insert replicated to about 30% of the level observed for the wild type. However, the corresponding virus consistently deleted most of the inserted fragment, suggesting that its presence was incompatible with a full replication cycle.
...
PMID:The 3' untranslated region of picornavirus RNA: features required for efficient genome replication. 749 95

Platelet-derived growth factor (PDGF) A-chain gene contains a long 5'-untranslated region (5'-UTR) of 850 bp. We evaluated the role of the 5'-UTR by chloramphenicol acetyltransferase (CAT) assay. CAT activity appeared when the fragment +99 bp downstream from the initiation site (+1) was present but disappeared in the fragment to +184 bp. It appeared again at +338 bp but disappeared again to +609 bp. The fragment from +99 to +184 inhibited CAT activity by a post-transcriptional mechanism, as RNA of CAT was observed but CAT activity was not.
...
PMID:Gene regulation by the 5'-untranslated region of the platelet-derived growth factor A-chain. 751 95


1 2 3 4 5 Next >>

---