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

Nervous system tissues from a number of patients with idiopathic neurological disorders were examined for biochemical evidence of RNA tumor virus infection. RNase-sensitive DNA polymerase activity was found in a cytoplasmic particulate fraction from two patients with Guamanian amyotrophic lateral sclerosis (ALS) but not in brains from two normal U.S. individuals. The buoyant density of the enzyme-containing fraction was 1.16-1.18 g/ml and could be converted to a denser region of the gradient (1.24 g/ml) by treatment with the nonionic surfactant, Sterox. The cation and detergent requirements for the endogenous RNase-sensitive DNA polymerase reaction were determined. The early (5 min) endogenous reverse transcriptase product was analyzed by cesium sulfate gradient centrifugation. RNase- and heat-sensitive RNA-DNA hybrids were detected in the product analysis of two ALS, one Parkinsonism-dementia (PD) brain, and two brains from asymptomatic Chamorros but not in brains from normal U.S. individuals and a number of patients with neuro-psychiatric disorders. The DNA product was a 4.5S heteropolymer that hybridized more extensively to RNA extracted from the enzyme-containing pellet from PD brain as compared to a similar fraction from normal U.S. brain. The DNA product appeared to be unrelated to Rausvher or visna virus 70S RNA as determined by RNA-[-3H]DNA hybridization.
...
PMID:RNA-instructed DNA polymerase activity in a cytoplasmic particulate fraction in brains from Guamanian patients. 4 90

Reticuloendotheliosis viruses (REV) contain an endogenous RNA-directed DNA polymerase activity. The endogenous DNA polymerase activity can be elicited in purified preparations of REV by treatment with nonionic detergents. The enzyme activity has a strong preference for manganous ions. Therefore, appreciable endogenous DNA polymerase activity can be demonstrated only if the reaction mixture contains appropriate concentrations of manganous ions. Enzyme activity can be inhibited by pretreatment with RNase or deletion of one or more deoxyribonucleoside triphosphates from the reaction mixture. In contrast, actinomycin D has little effect in initial DNA synthesis. The results from both velocity and equilibrium centrifugation indicate that the nascent chains of product DNA are associated with 60S viral RNA. The DNA product of the endogenous DNA polymerase reaction is hybridizable to REV RNA, but not to avian leukosis virus RNA.
...
PMID:Characterization of endogenous RNA-directed DNA polymerase activity of reticuloendotheliosis viruses. 5 36

Intracisternal A particles from the FLOPC-1 line of BALB/c myeloma have been shown to contain high-molecular-weight RNA (60 to 70S) that is sensitive to RNase, alkali degradation, and heat but resistant to Pronase treatment. The intracisternal A-particle RNA contains tract of poly (A) approximately 180 nucleotides long. As shown in a reconstitution experiment, by antigenic analysis of A-particle preparation and the SC cytopathogenicity assay, the 70S RNA was not due to contamination by type C virus particles. The FLOPC-1 intracisternal A particles also possess an endogenous RNA-dependent DNA polymerase. The enzyme required Mn2+ or Mg2+, dithiothreitol, detergent, and four deoxyribonucleoside triphosphates for maximum activity. Enzymatic activity was maximally stimuated by poly (rC)-oligo (dG)12-18 and less with poly (rG)-oligo (dC)10 or poly (rA)-oligo (dT)12-18 as compare with synthetic DNA/DNA duplex templates such as poly (dA)-oligo (dT)12-18. The enzyme can utilize the A-particle endogenous RNA as template as shown by analysis of the early and late DNA products of the endogenous reaction by CsSO4 isopycnic gradient centrifuation and hybridization of purified 70S or 35S A-particle RNA with the purified complementary DNA product. Approximately 50% of the A-particle complementary DNA also hybridized with oncornavirus RNA.
...
PMID:Intracisternal A particles from FLOPC-1 BALB/c myeloma: presence of high-molecular-weight RNA and RNA-dependent DNA polymerase. 5 76

The Friend erythroleukemia cell line T3-C12, which produces Friend murine leukemia virus (F-MuLV) and can be induced to synthesize hemoglobin by dimethyl sulfoxide (DMSO), was monitored for viral RNA-dependent DNA polymerase reverse transcriptase (RT) activity. The amount of viral 60-70S RNA released from DMSO-treated cells was unaffected or increased compared to that from control cells, while RT activity from treated cells was decreased. Accordingly, the specific activity in F-MuLV from DMSO-treated cells expressed as RT/70S RNA was decreased to 8% of the control activity. The 5-bromo-2'-deoxyuridine added to cultures containing DMSO reversed the differentiation process, and the F-MuLV thus treated did not exhibit the reduced RT activity normally observed in DMSO-treated virus. Cell-free F-MuLV incubated with and without DMSO showed the same RT activity, indicating that DMSO itself did not inhibit RT activity. However, when F-MuLV-containing pellets from control and DMSO-treated culture fluids were mixed, there was marked inhibition of the control RT activity, suggesting that RNase hybrid activity was stimulated or that an inhibitor was produced. Assays of F-MuLV-RNase hybrid released from control and DMSO-treated cells showed no difference in activity, indicating that a specific inhibitor of RT was produced or activated. Additions of certain nucleotide triphosphates to RT incubation mixtures did not result in any stimulation of RT activity in DMSO-treated F-MuLV, suggesting that phosphatase was not responsible for the observed inhibition. The results suggested that DMSO treatment of T3-C12 cells caused a reduction in viral RT activity by stimulating the production of an inhibitor, the nature of which is unknown.
...
PMID:Viral reverse transcriptase suppression associated with erythroid differentiation of Friend leukemia cells. 6 77

Tryptophanyl-tRNA was specifically labeled at the 3' end with [3H]tryptophan and cleaved in half with RNase under denaturing conditions, and the 3' half was shown to hybridize exclusively at the 5' end of avian myeloblastosis virus RNA. The RNA-dependent DNA polymerase of avian myeloblastosis virus is capable of efficiently binding the 3' half of the primer molecule.
...
PMID:Primer recognition by avian myeloblastosis virus RNA-directed DNA polymerase. 6 28

These studies were designed to determine if RIDP was present in a particulate fraction of brains from patients with ALS and PD. Evidence that we have detected RIDP is as follows: (a) DNA polymerase activity persists in the presence of concentrations of actinomycin D and distamycin that inhibit most DNA-directed DNA synthesis (25); (b) the majority of endogenous DNA polymerase activity is sensitive to prior treatment with RNase; (c) the early reaction product is a 4-5 S DNA heteropolymer joined by hydrogen bonds to an RNA molecule; and (d) the purified [3H]DNA product anneals to RNA extracted from the enzyme-containing pellet more extensively than to normal brain RNA or poly(rA). The enzyme activity is in a cytoplasmic particle that can be sedimented at high speed and has the buoyant density of RNA tumor viruses (1.16-1.18 gm/ml). This particulate fraction is not disrupted by physical manipulation and maintains its characteristic density with repeated centrifugations. Treatment with the nonionic surfactant Sterox changes the buoyant density of the enzyme-containing particle to 1.24 gm/ml, the density of the onconavirus virion core. Synthesis of RNA-DNA hybrids by an endogenous reverse transcriptase reaction was found only in normal and diseased Chamorro brains. Examination of a limited number of normal and diseased brains from individuals who lived in the United States produced negative results (39). Definitive characterization of this polymerase activity and identification as a true viral polymerase will depend on purification of biochemically active quantities of this polymerase to determine its template specificities, its cation preference, the fidelity of its transcription product, as well as its antigenic relationship to animal virus and human leukemic RIDP. Of critical importance in these studies will be differentiation of this activity from normal brain DNA polymerase gamma and terminal deoxynucleotidyltransferase.
...
PMID:RNA tumor viruses as causative agents of chronic neurological disease. 6 87

Equine infectious anemia (EIAV) is shown to have an associated RNA-instructed DNA polymerase similar in its cofactor requirements and reaction conditions to the RNA tumor virus DNA polymerases. Demonstrating this DNA polymerase activity requires a critical concentration of a nonionic detergent, all four deoxyribonucleoside triphosphates, and a divalent metal ion. The reaction is sensitive to RNase, and a substantial fraction of the FNA synthesized is complementary to viral RNA. The detection of a complex of tritium-labeled polymerase product DNA-template RNA, which sedimented at 60S to 70S, provided evidence that EIAV contains high-molecular-weight RNA. These results, obtained with both virus propagated in cell culture and virus from the serum of an experimentally infected horse, indicate that EIAV may properly be considered a member of the family Retroviridae. They may also be pertinent to the mechanism(s) of viral persistence and periodic recrudescence of disease in chronically infected horses.
...
PMID:RNA-dependent DNA polymerase associated with equine infectious anemia virus. 6 19

Human ribonucleases were purified from the sera of Hodgkin's disease patients by sequential column chromatography. The purified enzyme interacted with reverse transcriptase of Rauscher leukemia virus and formed an additive complex of Mr = 130,000. RNase and oligo(dG)-directed reverse transcriptase activities were diminished in the complex. The complex could be dissociated with the subsequent restoration of both activities in the presence of spermidine. The molecular weight of the complex suggest that the 2 RNase molecules bind to a single reverse transcriptase molecule.
...
PMID:Complexing Rauscher leukemia virus reverse transcriptase with human plasma ribonuclease from Hodgkin's disease patients. 7 69

The sequence of 129 nucleotides next to the poly(A) tail of encephalomyocarditis virus RNA has been determined by rapid gel sequencing of cDNA synthesized with DNA polymerase I or reverse transcriptase and a phasing primer, [5'-32P]p(dT)8dC. The sequence is in accord with (a) the pyrimidine tracts which were mapped in blocks along the cDNA, (B) the sequences of seven characteristic T1 RNase oligonucleotides in the RNA transcribed from the cDNA with RNA polymerase, and (c) a limited amount of sequence deduced by partial spleen phosphodiesterase digestion and depurination of endonuclease IV oligonucleotides. The 3' end shows little secondary structure on its own. Ten nonsense codons block all three reading frames such that at least 26 nucleotides do not code for protein. The possible function of a homology A-A-U-A-A-A with other polyadenylated RNAs is discussed.
...
PMID:Sequence of 129 nucleotides at the 3'-terminus of encephalomyocarditis virus RNA. 7 85

Extracts from over 100 normal human placentas have been examined for RNA-directed DNA polymerase (DNA nucleotidyltransferase, EC 2.7.7.7) activity. More than 80% of these placentas contained this enzyme activity, which banded at a density of 1.15-1.17 g/ml in sucrose. After heat treatment, this enzyme activity was shifted in density to 1.22-1.24 g/ml. The enzymatic activity was greater with (rC)n.(dG)12-18 than with (dC)n.(dG)12-18 and was not stimulated by (dG)12-18 alone. The product of the endogenous reaction, which was sensitive to RNase, had the characteristics of a small DNA associated with a large RNA by hydrogen bonding. Electron microscopic inspection of the material with a density of 1.15-1.17 g/ml revealed numerous retrovirus-like particles with central electron-dense cores and double-membraned envelopes. The enzyme may be associated with the retrovirus-lik particles noted in the trophoblast layer of some human placentas.
...
PMID:Normal human placentas contain RNA-directed DNA polymerase activity like that in viruses. 8 52


1 2 3 4 5 6 7 8 9 10 Next >>

---