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)

The terminal portion of the short arm of the human Y (Yp) chromosome encodes a zinc-finger DNA binding protein (ZFY). A highly homologous gene, ZFX, is encoded on Xp. The potential of the zinc finger motif for regulating the expression of other genes suggests a role for this protein in the development of malignancy. Prostate adenocarcinoma is a malignancy of male-specific tissue, the incidence of which increases beyond the fifth decade of life. We have analyzed samples of human prostate adenocarcinoma for the expression of ZFY and ZFX transcripts. We found expression of ZFY transcripts in 3 of 31 prostate adenocarcinomas by using Northern analysis. No ZFY or ZFX transcripts were detected in normal hypertrophic prostate tissue on Northern analysis. In one prostate adenocarcinoma, high levels of the 5.1 kb ZFY and the 8.0 and 6.3 kb ZFX transcripts were present. In addition, this high-grade tumor contained a novel 4.3 kb transcript. When we used reverse transcriptase PCR (RT-PCR) to analyze these same samples, the number of tumors expressing ZFY and/or ZFX transcripts increased to 20 of 31. Transcripts for these genes were also present in the DU-145 and LNCaP human prostate adenocarcinoma cell lines. In 2 of the 6 benign prostatic hypertrophy (BPH) tissues analyzed by RT-PCR, barely detectable products of ZFY were observed, and none contained ZFX products. Southern analysis revealed that the portion of the Y chromosome which contains the ZFY gene was not lost from the majority of the tumor cells in any of the prostate malignancies examined.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:ZFY gene expression and retention in human prostate adenocarcinoma. 768 Aug 90

The oncogene GLI is amplified and expressed in some cases of human malignant glioma and undifferentiated childhood sarcoma and is the prototype for a gene family characterized by a highly conserved set of five tandem zinc fingers and a consensus cysteine-histidine link. This zinc finger motif has been shown to bind DNA with sequence specificity and may mediate transcriptional regulation. Since GLI is expressed in embryonal carcinoma cell lines but not in most normal adult tissues and shows significant sequence similarity within its zinc finger domain to cubitus interruptus dominant (ciD), a Drosophila segmentation gene known to be important in the morphogenesis of the posterior portion of each larval segment, we established the temporal and tissue expression patterns of the mouse homologue of human GLI in day 10 through 18 mouse embryos with Northern blotting, reverse transcriptase coupled PCR, and in situ hybridization. gli transcripts were demonstrated on days 10 through 18 of mouse embryonic development as well as in normal adult uterus, brain, testis, and limb. Tissue expression of gli during gestation was demonstrated in Meckel's precartilage mesenchyme, the basis occipitus, rib mesenchymal condensations, primordial vertebral bodies, digital mesenchymal condensations in forefoot and hindfoot plates, the ependymal layer of the spinal cord, and the mesoderm of the gastrointestinal tract. Expression persisted throughout gestation in developing bone and cartilage of the extremities, the ribs, and the vertebral bodies, as well as the gastrointestinal tract mesoderm. These findings support a role for gli family genes in normal craniofacial and digital development in mammals first suggested by the demonstration of translocation breakpoints within the GLI3 gene in families with the Greig cephalopolysyndactylyl syndrome and subsequently by reduced gli3 expression in the mouse mutant extra toes. It is surprising that a single gene would be expressed in such a wide range of mesenchymal structures.
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PMID:gli, a zinc finger transcription factor and oncogene, is expressed during normal mouse development. 836 25

CR1 elements are a family of retroposons. They are classified as long interspersed elements (LINEs) or non-long-terminal-repeat (non-LTR) retrotransposons, and they have been found in the genomes of many vertebrates. However, they have been only partially characterized, and only a 2-kb region of the 3' end of chicken CR1 has been sequenced. In the present study, we determined the entire consensus sequence of CR1 elements in the turtle genome, designated PsCR1. The first open reading frame (ORF1) of PsCR1 has two unusual arrangements of Cys residues. One of them includes a zinc finger motif, CX2CX14CX2C. The putative zinc finger has cysteine residues with identical spacing and a similar amino acid composition to those found in the species-specific transcription initiation factors SL1 and TIF-IB. The 5' untranslated region (5' UTR) of PsCR1 contains a sequence similar to part of the human L1 promoter, L1 site A, and several cis elements of the type found in eukaryotic genes. Within a region of about 500 bp, there are nine "E boxes," cis elements that are recognized by the basic helix-loop-helix (bHLH) family of proteins. This observation raises the possibility that cellular transcription factors that bind to these sequences might act in concert to regulate the expression of PsCR1. The extent of the sequence divergence of the 3' UTR of CR1 between species was found to be lower than the rate of nonsynonymous substitutions per site in ORF2, suggesting that a strict functional constraint must exist for this region. This result strongly suggests that the conserved 3'-end sequence of CR1 is the recognition site for the reverse transcriptase of CR1. A discussion is presented of a possible mechanism for the integration of CR1 elements and also of the intriguing possible recruitment of the reverse transcriptase for the retroposition of SINEs.
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PMID:Determination of the entire sequence of turtle CR1: the first open reading frame of the turtle CR1 element encodes a protein with a novel zinc finger motif. 940 32

We have determined the complete nucleotide sequence of a replication-competent clone of bovine foamy virus (BFV) and have quantitated the amount of splice pol mRNA processed early in infection. The 544-amino-acid Gag protein precursor has little sequence similarity with its primate foamy virus homologs, but the putative nucleocapsid (NC) protein, like the primate NCs, contains the three glycine-arginine-rich regions that are postulated to bind genomic RNA during virion assembly. The BFV gag and pol open reading frames overlap, with pro and pol in the same translational frame. As with the human foamy virus (HFV) and feline foamy virus, we have detected a spliced pol mRNA by PCR. Quantitatively, this mRNA approximates the level of full-length genomic RNA early in infection. The integrase (IN) domain of reverse transcriptase does not contain the canonical HH-CC zinc finger motif present in all characterized retroviral INs, but it does contain a nearby histidine residue that could conceivably participate as a member of the zinc finger. The env gene encodes a protein that is over 40% identical in sequence to the HFV Env. By comparison, the Gag precursor of BFV is predicted to be only 28% identical to the HFV protein.
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PMID:The nucleotide sequence and spliced pol mRNA levels of the nonprimate spumavirus bovine foamy virus. 949 74

The bmi-1 gene was identified as a common proviral integration site in Moloney murine leukemia virus. In the present studies, we cloned and sequenced the rat bmi-1 gene by reverse transcriptase-polymerase chain reaction (RT-PCR) using degenerate PCR primers of homologous sequences between mouse and human. We found 93% identity to the mouse bmi-1 cDNA and 90% identity to the human bmi-1. The open reading frame encodes a protein of 324 amino acids. In the deduced amino acid sequence we observed 95% and 94% homology to the mouse and human, respectively. The structural motifs, a novel zinc finger motif and a putative helix-turn-helix motif, were conserved in the predicted rat BMI-1 protein. We also confirmed ubiquitous expression of bmi-1 in normal tissues except brain. These results suggest functional conservation of the bmi-1 gene in the rat.
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PMID:Cloning of the rat proto-oncogene bmi-1. 992 60

This study describes the consensus sequence of a full-length (4585bp) non-LTR retrotransposon from the fugu fish, Fugu rubripes. The retrotransposon, termed Maui, is represented by a group of very similar LINE elements found as multiple copies within the fish genome. Two long open reading frames (ORFs) are predicted from the sequence. The first ORF has a domain resembling a novel zinc finger motif recently found in both a turtle and a chicken (CR1) non-LTR retrotransposon. The second ORF includes sequences homologous to the endonuclease, reverse transcriptase and carboxy-terminal domains found in other non-LTR retrotransposons. Sequence comparisons of the predicted translation products of the two ORFs indicate that Maui is most closely related to a class of non-LTR retrotransposons represented by the CR1-like elements (chicken repeat 1 elements) that are present in several avian species and have recently been described in the turtle Platemys spixii. The sequence of the 3' untranslated region also supports this relationship since Maui resembles the CR1 like elements in not having a poly-A tail.
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PMID:A LINE element from the pufferfish (fugu) Fugu rubripes which shows similarity to the CR1 family of non-LTR retrotransposons. 1002 50

Three copies of the gene that encodes cytochrome c oxidase subunit Vb were isolated from the pea (PscoxVb-1, PscoxVb-2, and PscoxVb-3). Northern Blot and reverse transcriptase-PCR analyses suggest that all 3 genes are transcribed in the pea. Each pea coxVb gene has an N-terminal extended sequence that can encode a mitochondrial targeting signal, called a presequence. The localization of green fluorescent proteins fused with the presequence strongly suggests the targeting of pea COXVb proteins to mitochondria. Each pea coxVb gene has 5 intron sites within the coding region. These are similar to Arabidopsis and rice, although the intron lengths vary greatly. A phylogenetic analysis of coxVb suggests the occurrence of gene duplication events during angiosperm evolution. In particular, 2 duplication events might have occurred in legumes, grasses, and Solanaceae. A comparison of amino acid sequences in COXVb or its counterpart shows the conservation of several amino acids within a zinc finger motif. Interestingly, a homology search analysis showed that bacterial protein COG4391 and a mitochondrial complex I 13 kDa subunit also have similar amino acid compositions around this motif. Such similarity might reflect evolutionary relationships among the 3 proteins.
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PMID:Isolation and characterization of the pea cytochrome c oxidase Vb gene. 1742 63

Ribosomal RNA genes are encoded by large units clustered (18S, 5S, and 28S) in the nucleolar organizer region in several organisms. Sometimes additional insertions are present in the coding region for the 28S rDNA. These insertions are specific non-long terminal repeat retrotransposons that have very restricted integration targets within the genome. The retrotransposon present in the genome of Rhynchosciara americana, RaR2, was isolated by the screening of a genomic library. Sequence analysis showed the presence of conserved regions, such as a reverse transcriptase domain and a zinc finger motif in the amino terminal region. The insertion site was highly conserved in R. americana and a phylogenetic analysis showed that this element belongs to the R2 clade. The chromosomal localization confirmed that the RaR2 mobile element was inserted into a specific site in the rDNA gene. The expression level of RaR2 in salivary glands during larval development was determined by quantitative RT-PCR, and the increase of relative expression in the 3P of the fourth instar larval could be related to intense gene activity characteristic of this stage. 5'-Truncated elements were identified in different DNA samples. Additionally, in three other Rhynchosciara species, the R2 element was present as a full-length element.
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PMID:The R2 mobile element of Rhynchosciara americana: molecular, cytological and dynamic aspects. 1935 Apr 1

We characterized a novel type of plant non-LTR retrotransposons, identified as the BNR family, in sugar beet (Beta vulgaris) genomes. Although their ORF2 sequences were similar to those of previously analysed LINEs (long interspersed nuclear elements) of the L1 clade, their ORF1 sequences differ strongly from those of most plant LINEs. Two novel domains were identified, containing a conserved secondary motif, known as the RNA recognition motif (RRM). ORF1 lacks the zinc finger motif that is typical of plant LINEs, but has an RRM that is likely to have a RNA-binding function. BNR LINEs are highly diverse, and were characterized by gel-blot and fluorescent in situ hybridization, showing a widespread occurrence and clustering along chromosome arms. Insertion of BNR1 into a well-described satellite repeat was detected in two cultivars only, indicating recent activity. Database searches revealed the existence of LINE families possessing an ORF1 sequence similar to that of BNR in the genomes of higher plants such as poplar, lotus and soybean. Comparing their reverse transcriptase regions with those of other retrotransposons, these LINEs were assigned to the L1 clade, but form a distinct group, providing evidence of a major separation of L1 elements in plants. This indicates a common origin of BNR-like LINEs, suggesting that these elements form a sub-clade designated as the BNR sub-clade.
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PMID:BNR - a LINE family from Beta vulgaris - contains a RRM domain in open reading frame 1 and defines a L1 sub-clade present in diverse plant genomes. 1947 21

Hepadnaviruses replicate via reverse transcription of an RNA template, the pregenomic RNA (pgRNA). Although hepadnaviral polymerase (Pol) and retroviral reverse transcriptase are distantly related, some of their features are distinct. In particular, Pol contains two additional N-terminal subdomains, the terminal protein and spacer subdomains. Since much of the spacer subdomain can be deleted without detrimental effects to hepatitis B virus (HBV) replication, this subdomain was previously thought to serve only as a spacer that links the terminal protein and reverse transcriptase subdomains. Unexpectedly, we found that the C terminus of the spacer subdomain is indispensable for the encapsidation of pgRNA. Alanine-scanning mutagenesis revealed that four conserved cysteine residues, three at the C terminus of the spacer subdomain and one at the N terminus of the reverse transcriptase subdomain, are critical for encapsidation. The inability of the mutant Pol proteins to incorporate into nucleocapsid particles, together with other evidence, argued that the four conserved cysteine residues are critical for RNA binding. One implication is that these four cysteine residues might form a putative zinc finger motif. Based on these findings, we speculate that the RNA binding activity of HBV Pol may be mediated by this newly identified putative zinc finger motif.
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PMID:Four conserved cysteine residues of the hepatitis B virus polymerase are critical for RNA pregenome encapsidation. 1951 76


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