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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A set of probes was designed for the quantitation of HIV-1 RNA in infected cells by a molecular hybridization procedure called reversible target capture. Reversible target capture is analogous to sandwich hybridization, except that the link between hybrid complexes and the affinity support was reversible, allowing for repeated capture of hybrids on, and release from, fresh affinity support. Repeated cycles of capture resulted in a high degree of purification of hybrids from unreacted probe, thereby greatly reducing assay noise and increasing assay sensitivity. Probes against the HIV-1 pol gene were chosen because their target sequences were highly conserved among HIV-1 isolates, while being divergent enough to provide discrimination from other human T cell tropic viruses. Subpicogram quantities of HIV-1 pol gene RNA were measured with signal:noise ratios of over 10. Hybridization signal increased with increasing target RNA with a proportionality constant of 1.
Mol Cell Probes 1989 Mar
PMID:Probes for quantitating subpicogram amounts of HIV-1 RNA by molecular hybridization. 247 23

Antibodies raised against intercellular fluid antigens isolated from diseased tomato leaves have revealed that the fungal pathogen Fulvia fulva expresses genes for a fungal reverse transcriptase (RNA-dependent DNA polymerase). This enzyme is required for the replication of retroviruses and retroviral-like transposable elements and could provide a mechanism for increasing the mutation rate of fungal pathogens, perhaps explaining their ability to evolve new races rapidly. We report here the DNA sequence of a 225-bp clone from a lambda gt11 genomic library of F. fulva. This clone, designated P5, exhibits a high degree of sequence homology with the reverse transcriptase (pol) gene of the Drosophila melanogaster copia-like retrotransposon 17.6. Southern blot analysis of genomic DNA of F. fulva showed that P5-related sequences are moderately reiterated with 30-100 copies, some of which exhibit restriction fragment length polymorphism in different races of the pathogen. Western blot analysis of extracts from F. fulva with antibodies raised to purified reverse transcriptase (from human immunodeficiency virus-1) revealed immunoreactive proteins. Reverse transcriptase previously has been detected in a variety of organisms including yeast, insects, protozoa, and mammals, but to our knowledge, this is the first report of its occurrence in filamentous fungi.
Mol Plant Microbe Interact
PMID:Expression of reverse transcriptase genes in Fulvia fulva. 248 12

Members of two related families of transposable elements, Tx1 and Tx2, were isolated from the genome of Xenopus laevis and characterized. In both families, two versions of the elements were found. The smaller version in each family (Tx1d and Tx2d) consisted largely of two types of 400-base-pair tandem internal repeats. These elements had discrete ends and short inverted terminal repeats characteristic of mobile DNAs that are presumed to move via DNA intermediates, e.g., Drosophila P and maize Ac elements. The longer versions (Tx1c and Tx2c) differed from Tx1d and Tx2d by the presence of a 6.9-kilobase-pair internal segment that included two long open reading frames (ORFs). ORF1 had one cysteine-plus-histidine-rich sequence of the type found in retroviral gag proteins. ORF2 showed more substantial homology to retroviral pol genes and particularly to the analogs of pol found in a subclass of mobile DNAs that are supposed retrotransposons, such as mammalian long interspersed repetitive sequences, Drosophila I factors, silkworm R1 elements, and trypanosome Ingi elements. Thus, the Tx1 elements present a paradox by exhibiting features of two classes of mobile DNAs that are thought to have very different modes of transposition. Two possible resolutions are considered: (i) the composite versions are actually made up of two independent elements, one of the retrotransposon class, which has a high degree of specificity for insertion into a target within the other, P-like element; and (ii) the composite elements are intact, autonomous mobile DNAs, in which the pol-like gene product collaborates with the terminal inverted repeats to cause transposition of the entire unit.
Mol Cell Biol 1989 Jul
PMID:Composite transposable elements in the Xenopus laevis genome. 255 Jul 91

11 recombinant bacteriophages from the genomic library of Djungarian hamster genome, that carry MMTV-related sequences (MRS-Ps), have been cloned with the murine mammary cancer virus (MMTV) as a hybridization probe. The sequences are repeated 50 times in the genome. MRS-Ps contain the tracts of homology with the long end repeat MMTV, the genes pol and, possibly, env, but not with the gag gene. Sequencing of the 0,87 kb restrict, common to all EcoRI-BamHI clones, and the analysis of the sequence have demonstrated the high level of homology with the pol gene of MMTV and its origination from the somewhat functioning gene.
Mol Gen Mikrobiol Virusol 1989 Oct
PMID:[Cloning and analysis of the primary structure of an element, related to the murine mammary cancer virus, from the genome of the Djungarian hamster]. 255 24

Saccharomyces cerevisiae Ty elements are transposons closely related to retroviruses. The DNA sequence of a functional Ty element (TyH3) is presented. The long terminal repeat sequences are different, suggesting that TyH3 is a recombinant Ty element. A chromosomal Ty element near the LYS2 gene, Ty173, was found to be nonfunctional, even though it has no detectable insertions or deletions. The defect in Ty173 transposition is caused by a missense mutation giving rise to a Leu-to-Ile substitution in the TYB (pol) open reading frame. Several chromosomal Ty elements carry this lesion in their DNA, indicating that nonfunctional Ty elements are common in the yeast genome.
Mol Cell Biol 1988 Apr
PMID:The Saccharomyces cerevisiae genome contains functional and nonfunctional copies of transposon Ty1. 283 41

Only a fraction of retroviral primary transcripts are spliced to subgenomic mRNAs; the unspliced transcripts are transported to the cytoplasm for packaging into virions and for translation of the gag and pol genes. We identified cis-acting sequences within the gag gene of Rous sarcoma virus (RSV) which negatively regulate splicing in vivo. Mutations were generated downstream of the splice donor (base 397) in the intron of a proviral clone of RSV. Deletion of bases 708 to 800 or 874 to 987 resulted in a large increase in the level of spliced RSV RNA relative to unspliced RSV RNA. This negative regulator of splicing (nrs) also inhibited splicing of a heterologous splice donor and acceptor pair when inserted into the intron. The nrs element did not affect the level of spliced RNA by increasing the rate of transport of the unspliced RNA to the cytoplasm but interfered more directly with splicing. To investigate the possible role of gag proteins in splicing, we studied constructs carrying frameshift mutations in the gag gene. While these mutations, which caused premature termination of gag translation, did not affect the level of spliced RSV RNA, they resulted in a large decrease in the accumulation of unspliced RNA in the cytoplasm.
Mol Cell Biol 1988 Nov
PMID:Regulation of Rous sarcoma virus RNA splicing and stability. 285 Apr 70

The complete nucleotide sequence of a mouse retro-element is presented. The cloned element is composed of 4,834 base pairs (bp) with long terminal repeats of 568 bp separated by an internal region of 3,698 bp. The element did not appear to have any open reading frames that would be capable of encoding the functional proteins that are normally produced by retro-elements. However, some regions of the genome showed some homology to retroviral gag and pol open reading frames. There was no region in VL30 corresponding to a retroviral env gene. This implies that VL30 is related to retrotransposons rather than to retroviruses. The sequence also contained regions that were homologous to known reverse transcriptase priming sites and viral packaging sites. These observations, combined with the known transcriptional capacity of the VL30 promoter, suggest that VL30 relies on protein functions of other retro-elements, such as murine leukemia virus, while maintaining highly conserved cis-active promoter, packaging, and priming sites necessary for its replication and cell-to-cell transmission.
Mol Cell Biol 1988 Aug
PMID:Complete nucleotide sequence of a mouse VL30 retro-element. 285 Apr 74

Ty3, a retrotransposon of Saccharomyces cerevisiae, is found within 20 base pairs (bp) of the 5' ends of different tRNA genes. Determination of the complete nucleotide sequence of one Ty3 retrotransposon (Ty3-2) shows that the element is composed of an internal domain 4,748 bp long flanked by long terminal repeats of the 340-bp sigma element. Three open reading frames (ORFs) longer than 100 codons are present in the sense strand. The first ORF, TYA3, encodes a protein with a motif found in the nucleic acid-binding protein of retroviruses. The second ORF, TYB3, has homology to retroviral pol genes. The deduced amino acid sequence of the reverse transcriptase domain shows the greatest similarity to Drosophila retrotransposon 17.6, with 43% identical residues. The inferred order of functional domains within TYB3--protease, reverse transcriptase, and endonuclease--resembles the order in Drosophila element 17.6 and in animal retroviruses but is different from that found in yeast elements Ty1 and Ty2. A second Ty3 element (Ty3-1) from a standard laboratory strain was overexpressed and shown to transpose.
Mol Cell Biol 1988 Dec
PMID:Ty3, a yeast retrotransposon associated with tRNA genes, has homology to animal retroviruses. 285 94

The major pol alpha activity of CHO cells was purified 2 800-fold to near homogeneity and was characterized with respect to its physical and catalytic properties. The purified enzyme, upon analysis in denaturing 'activity' gels, displayed a major, 120 kilodalton, catalytically active core and two minor, catalytically inactive components of 180 and 135 kilodaltons. The native form of the enzyme behaved in velocity sedimentation and gel permeation experiments as an asymmetric protein of an apparent Mr. of 515 kilodaltons. The purified enzyme displayed catalytic behavior and inhibitor sensitivity typical of that displayed by other mammalian pol alphas. Specifically, the enzyme: was sensitive to n-ethylmaleimide and the pol alpha-specific inhibitors, BuPdGTP and aphidicolin; was subject to neutralization by specific monoclonal antibodies raised against human pol alpha; was devoid of detectable 3' to 5' exonuclease activity, and displayed a ribonucleotide-dependent DNA primase activity.
Mol Cell Biochem 1985 Oct
PMID:Purification and characterization of DNA polymerase alpha of Chinese hamster ovary cells. 300 2

The mutD(dnaQ) gene in Escherichia coli codes for the epsilon subunit of the DNA polymerase pol III holoenzyme. Previous work has shown that this gene lies adjacent to the gene coding for RNase H (rnh). The two products are translated from diverging promoters. Here we report on the 1.6 kb (1 kb = 10(3) bases or base-pairs) sequence of the region coding for both genes, and the transcripts encoded by them. mutD codes for two transcripts, one of whose origins lies within the rnh structural gene. Both transcripts overlap and are complementary to a region of the rnh transcript. Thus, they can potentially form double-stranded helices with rnh. Of the two possible double-stranded structures, the shorter does not interfere with a likely rnh ribosome binding site, while the longer one does. We suggest that this unique organization may regulate rnh translation rates.
J Mol Biol 1986 Jul 05
PMID:DNA sequence and coding properties of mutD(dnaQ) a dominant Escherichia coli mutator gene. 302 34


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