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 alpha beta DNA polymerase of avian myeloblastosis virus was treated with dimethyl sulfoxide to dissociate the enzyme subunits. The dimethyl sulfoxide treated enzymes were passed over phosphocellulose to purify and characterize the dissociated subunits as well as to remove the dimethyl sulfoxide. RNA-directed DNA polymerase, RNase H, and nucleic acid-binding activity were monitored, as well as the subunit structure (on sodium dodecyl sulfate-polyacrylamide gels) of the various enzyme species obtained. With 30% dimethyl sulfoxide, the majority of DNA polymerase and RNase H activities as well as the alpha subunit were displaced from the alpha beta DNA polymerase position on phosphocellulose (0.23 M potassium phosphate) to the alpha DNA polymerase position (0.1 M). The association of DNA polymerase and RNase H activities with the alpha subunit suggests that alpha is the enzymatically active subunit in alpha beta. In addition to alpha DNA polymerase, a minor polymerase species eluted from phosphocellulose at 0.4 M potassium phosphate. The dissociated beta subunit eluted from phosphocellulose at a wide range of salt concentrations (0.28 to 0.5 M potassium phosphate). The dissociated beta subunit bound 3H-labeled murine leukemia virus RNA and [3H]poly(dT)-poly(dA) approximately 20-fold more avidly than alpha DNA polymerase alone. In contrast to the results with the alpha subunit, there was no correlation between DNA polymerase and RNase H activity profiles and the elution profile of the beta subunit from phosphocellulose. These observations suggest the beta subunit is either enzymatically inactive or possesses limited DNA polymerase and RNase H activity when compared with the alpha subunit.
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PMID:Dissociation of alpha beta DNA polymerase of avian myeloblastosis virus by dimethyl sulfoxide. 5 61

Poly(vinylbenzo-18-crown-6), a water-soluble polymer endowed with ion-binding crown moieties as pendent groups, forms insoluble complexes with polyadenylate in the presence of K+; the corresponding monomeric benzo-18-crown-6, does not form a precipitate under the same conditions. In the presence of Na+ and Mn2+ which in aqueous solution complex weakly to crown compounds, no coprecipitation of the crown polymer and polyadenylate occurs; nevertheless, the crown polymer strongly binds to immobilized polyadenylate even under these conditions. The interactions of crown polymer with the poly-nucleotide result in a loss of templating ability of the latter. Using RNA-dependent DNA polymerase of murine leukemia virus it was found that (1) enzymatic action is efficiently inhibited even in the absence of ions which coprecipitate crown polymer and template, (2) inhibition is reversed by addition of excess polynucleotide and (3) monomeric crown does not inhibit the reaction.
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PMID:Ionophorous polymers. Interaction with polynucleotides and effects on RNA-directed DNA polymerase activity. 5 50

Subviral cores have been prepared from the oncornavirus-like particle found in human milks with the use of phospholipase C and ether or Sterox SL. The major protein of these cores has a molecular weight of 27,000 daltons, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This protein is found in the core fractions of reverse transcriptase-positive milks and is absent in negative milks. It is distributed in sucrose gradients only in those fractions containing cores and reverse transcriptase activity. The major core protein of the human milk oncornavirus-like particle is electrophoretically identical to the major core protein of the mouse mammary tumor virus.
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PMID:Identification and isolation of the major core protein from the oncornavirus-like particle in human milk. 6 99

The reverse transcriptase (RNA-directed DNA nucleotidyltransferase) from avian myeloblastosis virus is able to make an extensive, possibly complete, complementary DNA copy of intact poliovirus RNA. In the presence of high concentrations of deoxyribonucleoside triphosphates, ribonucleoside triphosphates, or sodium pyrophosphate, this DNA is the only species produced. Without these additives, however, a second size class of DNA is also synthesized. This material has a sedimentation coefficient between roughly 4 and 10 S and is produced later in the reaction, largely after synthesis of the larger complementary DNA has ceased. The smaller DNA consists primarily of material anticomplementary to the RNA template and contains a faithful and uniform representation of the viral sequences. It most likely arises by transcription of the larger DNA species.
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PMID:Anticomplementary nature of smaller DNA produced during synthesis of extensive DNA copies of poliovirus RNA. 6 59

A protein kinase associated with purified virions of avian myeloblastosis virus, BAI strain A, was highly purified by ion-exchange chromatography and gel filtration. On the basis of molecular sieving on Sephadex G-200, the enzyme protein appeared to have a molecular weight of about 50,000 to 60,000; disc gel electrophoresis in sodium dodecyl sulfate-acrylamide gels revealed the presence of at least two polypeptide chains; and isoelectric focusing on acrylamide gels revealed two protein bands with activity. Of the nonviral proteins used as phosphate acceptors, the greatest rate of phosphorylation was obtained with alpha-casein. Potential physiological substrates for this activity included specific virion polypeptide of avian myeloblastosis virus. One of the virion polypeptides found in association with reverse transcriptase activity from avian myeloblastosis virus accepted more phosphate than any of nonviral or viral polypeptides examined on the basis of nanomoles of 32P incorporated per milligram of protein.
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PMID:Protein kinase and phosphoproteins of avian myeloblastosis virus. 6 29

A new retravirus (SMRV) isolated from a squirrel monkey, Saimiri sciureus, has an Mg2+-dependen reverse transcriptase and a buoyant density of 1.17 g/cm3 in sucrose and 1.21 g/cm3 in cesium chloride, similar to the mouse mammary tumor virus and the Mason-Pfizer monkey virus. The polypeptide patter of SMRV as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was distinct from the reported polypeptide patterns of known retraviruses. Four major polypeptides of molecular weights 40,000, 20,000, 14,000 and 8,000 were resolved in virus propagated in human, mink, and canine cells. In A204 human rhabdomyosarcoma cells, a protein of 73,000 daltons (gp73) represented the major viral glycoprotein as determined by [3H]glucosamine labeling. Additional proteins were also observed, but their presence depended on the cell type in which the virus was propagated. In both species-and interspecies-specific assays, no antigenic relatedness was observed between SMRV and Mason-Pfizer monkey virus, mouse mammary tumor virus, baboon endogenous virus (BaLV), woolly monkey virus (SSV-1), murine leukemia virus, endogenous feline type C virus (RD-114), bovine leukemia virus, and equine infectious anemia virus. These findings indicate that SMRV represents a new retravirus and the first isolate from a New World monkey.
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PMID:Characterization of a retravirus isolated from squirrel monkeys. 6 28

From the same batch of virus, the four major avian viral structural proteins p27, p19, p15, and p12, the reverse transcriptase, the envelope glycoprotein gp85, and the high molecular weight 70 S RNA have been recovered. All proteins, except for gp85, have been purified by use of column chromatography procedures to apparent homogeneity as judged by sodium dodecyl sulfate-polyacrylamide gels and isoelectric focusing. A new isolation procedure for p12 by affinity column chromatography takes advantage of its nucleic acid binding properties. The recovery of nondenatured viral structural proteins is demonstrated by the proteolytic activity revealed by p15. The purified proteins were used for the production of monospecific antibodies. The 70 S RNA served as source for the isolation of 35 S RNA subunits.
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PMID:The isolation of avian viral RNA and polypeptides. 8 39

Total poly(A)-mRNA from polyribosomes of MOPC 21 mouse myeloma were investigated. Poly(A)-mRNA was released by two successive chromatography on oligo (dT)-cellulose. A 14S fraction of total poly(A)-mRNA was obtained and partially purified by sucrose gradient centrifigation followed by acrylamide gel electrophoresis. As estimated from the electrophoretic analysis, the 14S mRNA has three components, one of which appears to be 18S rRNA and two others--mRNAs with molecular weight of 5.2.10(5) and 3.8.10(5), respectively. Total poly(A)-mRNA and partially purified 14S mRNA were active when employed as a template in a reverse transcription and cell-free system from wheat germ. DNA complementary to the 14S mRNA was prepared with avian myeloblastosis virus RNA-dependent DNA polymerase. This cDNA was heterogeneous in size with the average size of about 800 nucleotides when analyzed by gel electrophoresis in 98% formamide. The maximal length was about 1100 nucleotides that consistent with full template length. About half of the translation product directed by the 14S mRNA migrated as mature L-chain Ig (upon polyacrylamide gel electrophoresis in sodium dodecylsulfate). The presented data suggested that 14S mRNA species contain mRNA L-chain Ig.
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PMID:[mRNA of mouse plasmacytoma. Reverse transcription and translation in cell-free systems]. 8 67

The 5S ribosomal RNA has been isolated, pure and intact, from rat liver (5 mg of 5S RNA from 150g of liver). The 5S RNA serves as a primer for calf thymus poly(A) polymerase with 20% of the efficiency of (Ap)3A. Bacterial 5S RNA and transfer RNA also serve as primers; rat liver 18S and 28S ribosomal RNAs support poly(A) synthesis poorly. Neither the 5S RNA primer nor the appended poly(A) tract is nicked or degraded by poly(A) polymerase, and initiation of poly(A) tracts on 5S RNA primers continues throughout the reaction period. The rate of initiation is dependent on the enzyme concentration; the ATP concentration affects the rate of elongation. The polyadenylated material increases in size over time, with the largest material reaching a size of 6.8 S in 5 h, corresponding to an appended poly(A) tract of 140 nucleotides. Using polyadenylated 5S RNA, oliog(dTY as primer, and avian myeloblastosis virus reverse transcriptase, we synthesized DNA complementary to 5S RNA. The complementary DNA has an apparent molecular weight (in alkaline sucrose gradients) of 4.3 X 10(4). Base composition analysis and nearest-neighbor analysis of the DNA are as expected for a complement of 5S RNA, indicating that the entire 5S sequence is copied. The complementary DNA hybridizes to 5S RNA with a R0t1/2 of 8.9 X 10(-4) mol.s.L-1. No hybrid is formed with Escherichia coli 16S and 23S ribosomal RNA, E. coli 5S ribosomal RNA, yeast transfer RNA, rat liver transfer RNA, or rat liver 18S and 28S RIBOSOMAL RNA. The Tm of the 5S RNA:5S DNA hybrid in 15 mM NaCl containing 1.5 mM sodium citrate is 74 degrees C, 2.5 degrees C below the theoretical melting temperature of a DNA duplex of 60% G + C. Analysis of the hybrid in buoyant density gradients also indicates that hybridization is both specific and precise. The complementary DNA anneals to calf thymus, rat liver, and salmon sperm DNAs but not to E. coli DNA. Annealing of 5S cDNA to calf thymus DNA with a C0t1/2 of 2.1 suggests that there are several thousand 5S RNA genes in the calf thymus genome (haploid). At least that number of 5S RNA genes is present in the salmon sperm genome.
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PMID:Enzymic polyadenylation of 5S ribosomal ribonucleic acid and synthesis of a complementary deoxyribonucleic acid. 8 57

The reverse transcriptase (RNA-dependent DNA nucleotidyltransferase) of the type C RNA virus produced by the human lymphoma cell line SU-DHL-1 was purified by ion-exchange chromatography of SU-DHL-1 culture fluids and repetitive affinity chromatography on poly(rC).agarose, as were the polymerases of several other type C viruses. The DHL-1 enzyme used template-primers at levels expected of a viral reverse transcriptase, and sodium dodecyl sulfate gel electrophoretic analysis of radioiodinated DHL-1 enzyme revealed a peak at a position corresponding to those of several other type C viral reverse transcriptases (namely, at 72,000-78,000 daltons). The purified enzyme was partially neutralized by antibodies specific for the reverse transcriptase of simian sarcoma virus. Two-dimensional analysis on thin-layer cellulose plates of tryptic hydrolysates of the radioiodinated enzymes of several viruses revealed that six peptides are common to the polymerases of simian sarcoma virus, gibbon ape leukemia virus, baboon endogenous virus, and the DHL-1 virus, and that two to four peptides are unique to each of these enzymes. The DHL-1 viral reverse transcriptase appears to be most closely related structurally to the enzymes of simian sarcoma virus, gibbon ape leukemia virus, and baboon endogenous virus. However, the DHL-1 viral enzyme differed from any one or combination of the other subhuman primate viral enzymes by virtue of its unique peptides. The implications of these findings with respect to the probable origin of the DHL-1 virus are discussed.
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PMID:Characterization of the reverse transcriptase of a type C RNA virus produced by a human lymphoma cell line. 9 23


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