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

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have isolated and sequenced a genomic clone from Saccharomyces cerevisiae that shows structural features of a novel retrotransposon, designated Ty4. The element is 6.2 kilobases in length, and its genetic organization of the deduced functional domains is similar to Ty1 and Ty2 and thus different from Ty3. In contrast to hitherto known Ty elements from yeast, Ty4 is flanked by long terminal tau-element repeats instead of delta or sigma sequences. Ty4 contains two overlapping open reading frames. The first open reading frame, TYA4, is 1230 base pairs long and encodes a protein with a motif found in the nucleic acid-binding gag-protein of retroviruses. The second 4395-base pair open reading frame, TYB4, encodes a polyprotein that has domains with significant homology to retroviral protease, integrase, reverse transcriptase, and RNase H, structurally arranged in that order. The deduced amino acid sequence shows the greatest similarity with Ty2 and Ty1. The overall identity of the deduced functional protein domains is 28% with Ty2, 25% with Ty1, 19% with copia from Drosophila, and 18% with Ty3. Examination of genomic DNA from several laboratory strains indicates that Ty4 is present in two to four copies. Ty4 mRNA is of low abundance as compared to other Ty retrotransposons. At the 3' end of Ty4, two "solo" delta-elements, a full length and an overlapping, truncated one, are associated.
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PMID:Ty4, a new retrotransposon from Saccharomyces cerevisiae, flanked by tau-elements. 132 82

A new P450 3A cDNA (RL33) has been cloned from a liver cDNA library of untreated male rat. RL33 is 2032 nucleotides in length and has an open reading frame of 502 amino acid residues. The nucleotide sequence of its 5'-noncoding region is completely identical with that of a genomic clone of P450 3A1 isolated by Burger et al. [Proc. Natl. Acad. Sci. USA 89, 2145-2149 (1992)]. Compared with rat P450 3A1, P450 RL33 showed 98 and 97% identities in the nucleotide and deduced amino acid sequences, respectively, with the deletion of 2 amino acids and substitution of 12 amino acids. These residues were localized around amino acids 107-230. Recently Kirita and Matsubara have isolated the same P450 3A cDNA (cDEX) from dexamethasone (DEX)-treated rat liver [Arch. Biochem. Biophys. 307, 253-258 (1993)]. Northern blot analysis using an oligonucleotide probe specific for P450 RL33/cDEX revealed that P450 RL33/cDEX mRNA was induced strongly by pregnenolone 16 alpha-carbonitrile and DEX and weakly by phenobarbital (PB) and triacetyloleandomycin. We constructed a P450 3A cDNA library by the reverse transcriptase-polymerase chain reaction using common primers to P450 RL33/cDEX, 3A1, and 3A2, and subcloned the cDNAs into pUC119. The expression level of P450 RL33/cDEX mRNA was investigated by identifying each clone with the above oligonucleotide probe. P450 RL33/cDEX mRNA represented over 70% of the total P450 3A mRNA from untreated, PB-, and DEX-treated rat liver. These results indicated that the major DEX-inducible form of P450 3A is P450 RL33/cDEX and not P450 3A1.
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PMID:A major glucocorticoid-inducible P450 in rat liver is not P450 3A1. 752 3

The pancreatic polypeptide family includes pancreatic polypeptide (PP), neuropeptide Y (NPY), and peptide YY (PYY). Members of the PP family regulate numerous physiological processes, including appetite, gastrointestinal transit, anxiety, and blood pressure. Of the multiple Y-type receptors proposed for PP family members, only the Y1 subtype has been cloned previously. We now report the cloning of an additional Y-type receptor, designated Y4, by homology screening of a human placental genomic library with transmembrane (TM) probes derived from the rat Y1 gene. The Y4 genomic clone encodes a predicted protein of 375 amino acids that is most homologous to Y1 receptors from human, rat, and mouse (42% overall; 55% in TM). 125I-PYY binding to transiently expressed Y4 receptors was saturable (pKd = 9.89) and displaceable by human PP family derivatives: PP (pKi = 10.25) approximately PP2-36 (pKi = 10.06) > PYY (pKi = 9.06) approximately [Leu31,Pro34]NPY (pKi = 8.95) > NPY (pKi = 8.68) > PP13-36 (pKi = 7.13) > PP31-36 (pKi = 6.46) > PP31-36 free acid (pKi < 5). Human PP decreased [cAMP] and increased intracellular [Ca2+] in Y4-transfected LMTK- cells. Y4 mRNA was detected by reverse transcriptase-polymerase chain reaction in human brain, coronary artery, and ileum, suggesting potential roles for Y4 receptors in central nervous system, cardiovascular, and gastrointestinal function.
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PMID:Cloning and functional expression of a human Y4 subtype receptor for pancreatic polypeptide, neuropeptide Y, and peptide YY. 759 11

Nineteen recombinant phages containing DNA from the region of Balbiani ring a (BRa), which develops on chromosome IV in cells of the special lobe of the Chironomus thummi salivary gland, were isolated from a Chironomus thummi genomic library. Three of the clones contained transposable element sequences that hybridized to more than 100 sites on all four Chironomus chromosomes, including constant and variable sites. Two handogous clones, lambda 24 (which lacks the transposable element) and lambda 43 (which contains this insertion) were investigated by nucleotide sequence analysis. The complete nucleotide sequence of the 4.8 kb transposable element from Chironomus thummi (NLR1Cth) is reported here. This element contains two overlapping open reading frames of 1887 (ORF1) and 2649 bp (ORF2). Three cysteine motifs are found in the sequence of ORF1. Sequence similarity was found between ORF2 and known genes of viruses and transposable elements which encode reverse transcriptase. The NLR1Cth element has no long terminal repeats and is flanked by short direct repeats of the sequence TATCACTGACAAC. A 24 bp poly(dA) sequence was found at the 3' end of the element. Based upon its structural organization and comparative analysis of its nucleotide sequence we suggest that this NLR1Cth element belongs to the class of non-LTR retrotransposons. The genomic clone pC6.10 was previously obtained by microdissection and cloning of DNA from polytene chromosome IV of Chironomus thummi. A 2.4 kb insertion contained part of the 3' terminal region of the NLR1Cth element, but this differed in sequence from the first copy by several nucleotide substitutions and a shorter poly (dA) tract at the 3' end.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The Chironomus thummi genome contains a non-LTR retrotransposon. 838 52

Decorin is a chondroitin/dermatan sulfate proteoglycan expressed by most vascular and avascular connective tissues and, because of its ability to interact with collagen and growth factors, has been implicated in the control of matrix assembly and cellular growth. To understand the molecular mechanisms involved in regulating its tissue expression, we have isolated a number of genomic clones encoding the complete decorin gene. The human decorin gene spans over 38 kb of continuous DNA sequence and contains eight exons and very large introns, two of which are 5.4 and > 13.2 kb. We have discovered two alternatively spliced leader exons, exons Ia and Ib, in the 5' untranslated region. These exons were identified by cloning and sequencing cDNAs obtained by polymerase chain reaction amplification of a fibroblast cDNA library. Using Northern blotting or reverse transcriptase PCR, we detected the two leader exons in a variety of mRNAs isolated from human cell lines and tissues. Interestingly, sequences highly (74-87%) homologous to exons Ia and Ib are found in the 5' untranslated region of avian and bovine decorin, respectively. This high degree of conservation among species suggests regulatory functions for these leader exons. In the 3' untranslated region there are several polyadenylation sites, and at least two of these sites could give rise to the transcripts of approximately 1.6 and approximately 1.9 kb, typically detected in a variety of tissues and cells. Using a genomic clone as the labeled probe and in situ hybridization of human metaphase chromosomes, we have mapped the decorin gene to the discrete region of human chromosome 12q23. This study provides the molecular basis for discerning the transcriptional control of the decorin gene and offers the opportunity to investigate genetic disorders linked to this important human gene.
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PMID:The human decorin gene: intron-exon organization, discovery of two alternatively spliced exons in the 5' untranslated region, and mapping of the gene to chromosome 12q23. 843 26

Acetyl-CoA carboxylase is a rate-limiting enzyme in the biogenesis of long-chain fatty acids. In the present study, the 5' end and flanking region of the acetyl-CoA carboxylase (ACC) gene was analysed in the chicken. A genomic clone was isolated containing the first three exons, the third one containing the ATG codon. Using nuclease-mapping experiments and primer-extension analyses, the transcription-initiation site was located 153 nucleotides upstream of the ATG codon. In contrast with rat ACC gene expression, reverse transcriptase PCR analysis performed on chicken liver mRNA did not reveal alternative splicing in the 5'-untranslated region of these messengers. The promoter region is very G+C rich, and contains no TATA or CAAT boxes. Analysis by transient transfection in a human hepatoma cell line (HepG2) demonstrates that the promoter activity requires the presence of symmetrical sequences located upstream of the GC boxes. Transcription of this gene is found to be controlled by tri-iodothyronine in HepG2 cells, but the sequence responsible for the tri-iodothyronine response is not the consensus tri-iodothyronine-responsive element localized in the promoter. These results bring new insights to the regulation of the chicken ACC gene which differs from that of the rat.
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PMID:Cloning and characterization of the 5' end and promoter region of the chicken acetyl-CoA carboxylase gene. 867 77

The expression of two closely related peroxidase isogenes, Shpx6a and Shpx6b, of the legume Stylosanthes humilis was studied using isogene-specific reverse transcriptase PCR techniques. Results indicated that transcripts of both genes were rapidly induced following inoculation with the fungal pathogen Colletotrichum gloeosporioides, wounding and treatment with the defense regulator methyl jasmonate (MeJA). In contrast treatment of leaves of S. humilis with abscisic acid (ABA) and salicylic acid (SA) did not induce transcripts of either isogene. A genomic clone containing the Shpx6b gene was isolated and 594 bp of 5' sequence upstream of the translation start was fused in frame to the coding region of the uidA reporter gene and introduced into tobacco. Expression from the Shpx6b promoter in transgenic plants was determined by histochemical staining and quantitative assays of beta-glucuronidase (GUS). In transgenic tobacco, GUS expression was detected in cotyledons, vascular cells of young leaves, anthers, pollen, and the stigma and style. Wounding of the tobacco plants produced very localized GUS staining. Much more extensive staining for GUS was observed following inoculation of tobacco leaves with conidia of the fungal pathogen Cercospora nicotianae and the inoculation of wound sites with mycelium of the Oomycete pathogen Phytophthora parasitica var. nicotianae. Treatment of mature leaves with methyl jasmonate induced GUS activity while treatment with ABA, SA, and H2O2 had no effect. A similar strong induction of GUS activity was measured in young transgenic seedlings germinated on MeJA while some, but much weaker, induction of GUS activity was observed in seedlings treated with SA. The sequence of the promoter contained motifs homologous to putative cis elements in other plant genes responsive to MeJA. The Shpx6b gene is the first plant peroxidase gene shown to be induced by both microbial pathogens and MeJA and its promoter will be useful for investigations of signaling processes during fungal infection and for the expression of foreign gene products at infection sites.
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PMID:A peroxidase gene promoter induced by phytopathogens and methyl jasmonate in transgenic plants. 910 Mar 78

Plants of Arabidopsis thaliana pre-treated at 37 degrees C for 2 h can survive an otherwise lethal heat shock at 45 degrees C. Differential display reverse transcriptase-PCR (DDRT-PCR) was utilized to clone DNA fragments corresponding to mRNAs specifically expressed in conditions of induced thermotolerance or of expression of thermotolerance. One of these DDRT-PCR fragments enabled the isolation of a genomic clone pAt1.3EX, containing the sequence Athsp23.5, the gene for a low-molecular-weight (LMW) heat shock protein (HSP), AtHSP23.5. Athsp23.5 is low- or single-copy in the Arabidopsis genome and its open reading frame is interrupted by a 137 bp intron. Analysis of the sequence suggests AtHSP23.5 is targeted to the mitochondrion. The steady-state level of the AtHSP23.5 mRNA varied significantly according to the heat treatment, increasing on heat shock (transfer from 22 degrees C to 37 degrees C), with a further increase during expression of thermotolerance (transfer from 22 degrees C to 37 degrees C and then to 45 degrees C). Expression was low after an abrupt stress (from 22 degrees C to 45 degrees C). This behaviour was different from that observed for other LMW HSP mRNAs that were present at high level at 37 degrees C, but did not increase significantly in condition of expression of thermotolerance, and reached a considerable steady-state level also during the abrupt stress at 45 degrees C. The retrotranscription of AtHSP23.5 mRNA followed by amplification with two primers encompassing the intron allowed for the isolation of an almost full-length cDNA sequence. The sequence analysis of the two cDNAs obtained from condition 22 degrees C-->37 degrees C and condition 22 degrees C-->45 degrees C suggested that in both cases the intron had been correctly spliced. The importance of correct intron splicing in survival at high temperatures and the role of mitochondrial HSP in induction and expression of thermotolerance are discussed.
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PMID:Differential display-mediated isolation of a genomic sequence for a putative mitochondrial LMW HSP specifically expressed in condition of induced thermotolerance in Arabidopsis thaliana (L.) heynh. 922 62

Latent membrane protein 1 (LMP 1) is one of two Epstein-Barr virus (EBV)-encoded proteins that expressed in nasopharyngeal carcinoma (NPC) cells. Previous studies showed that a 3.5-kb transcript of the LMP 1 gene, in addition to the 2.8-kb transcript, was detected in a B95-8-EBV-containing, nude mice-passaged NPC tumor, C15. This indicated that a transcript was initiated from a region 5' to the putative promoter, ED-L1. We have isolated an EBV variant from a NPC tissue, and this virus strain contained a more pathogenic LMP 1 gene. DNA sequence analysis of the 5'-upstream region showed distinct variations as compared to that of B95-8 strain. To test if the LMP 1 gene of the NPC strain also contained an upstream promoter, we generated a series of deletion plasmids encompassing positions -1,030 to +20 of the LMP 1 promoter and tested for their abilities to drive the expression of the reporter gene in human epithelial cell lines, C-33A and NPC-TW076. We found that the region between -643 and -496 contained a promoter activity that was approximately five-fold higher than the putative promoter, ED-L1. This region between -643 and -496 was designated as ED-L1E. C-33A cells containing the genomic clone pT7(E) or the clone that had deleted a 94-bp ED-L1 sequence (delta94) was used to determine the transcription initiation sites by RNase protection assay. Results showed that a transcription initiation site was located at nucleotide 170,099 ("A") of EBV genome. The transcript was expressed in NPC biopsies and in human primary normal epithelial cells transfected with pT7(E) and delta94, respectively, as examined by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Furthermore, the ED-L1E was not regulated by the EBV-encoded nuclear antigen 1-mediated transcriptional enhancer family of repeats (FR) in C-33A cells. Our results suggested that the ED-L1E was specifically activated in epithelial cells. The biological significance of the selective usage of the ED-L1E promoter was discussed.
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PMID:Identification of a promoter for the latent membrane protein 1 gene of Epstein-Barr virus that is specifically activated in human epithelial cells. 926 Sep 26

Two partial chicken POU domain genes were isolated by genomic library screening and reverse transcriptase-polymerase chain reaction (RT-PCR). A cDNA clone encoding the POU domain of Brn-3a, which showed near identity to the human Brn-3a sequence (100% amino acid identity), was isolated and mapped to chicken linkage group E48. A Skn-1/Epoc-1/Oct-11 genomic clone was identified and mapped to chicken linkage group E49. This mapping identified a syntenic group in chicken linkage group E49 that was conserved with human chromosome 11q23 and mouse chromosome 9.
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PMID:Isolation and mapping of two chicken POU family genes and the identification of a syntenic group with human and mouse. 936 95


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