The Experts below are selected from a list of 27 Experts worldwide ranked by ideXlab platform
Joann C. Leong - One of the best experts on this subject based on the ideXlab platform.
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Human placentas contain a specific inhibitor of RNA-directed DNA Polymerase (reverse transcriptase/development/retrovirus/RNA-dependent DNA nucleotidyltransferase)
2020Co-Authors: Jay A. Nelson, J. A. Levyt, Joann C. LeongAbstract:Human placental extracts contain a specific in- hibitor of mammalian retroviral RNA-directed DNA Polymerase (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7) activity. This inhibitor copurifies with retrovirus-like particles in human placental extracts. The inhibitor can be re- moved from these particles by salt extraction, which leads to the recovery of the Polymerase activity. Thus, the inhibitor does not irreversibly inactivate the particle-associated RNA-directed DNA Polymerase activity. The inhibitory preparation contained no nu- clease, protease, or phosphatase activity. Because its inhibitory action can be eliminated by the addition of more virus to the re- action, nonspecific inactivation of enzyme substrate has been ruled out. A partial characterization of the inhibitor indicates that it is (i) insensitive to ether, trypsin, and phospholipase C; (ii) stable to heat and pH 2-12; and (iii) nondialyzable.
Jay A. Nelson - One of the best experts on this subject based on the ideXlab platform.
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Human placentas contain a specific inhibitor of RNA-directed DNA Polymerase (reverse transcriptase/development/retrovirus/RNA-dependent DNA nucleotidyltransferase)
2020Co-Authors: Jay A. Nelson, J. A. Levyt, Joann C. LeongAbstract:Human placental extracts contain a specific in- hibitor of mammalian retroviral RNA-directed DNA Polymerase (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7) activity. This inhibitor copurifies with retrovirus-like particles in human placental extracts. The inhibitor can be re- moved from these particles by salt extraction, which leads to the recovery of the Polymerase activity. Thus, the inhibitor does not irreversibly inactivate the particle-associated RNA-directed DNA Polymerase activity. The inhibitory preparation contained no nu- clease, protease, or phosphatase activity. Because its inhibitory action can be eliminated by the addition of more virus to the re- action, nonspecific inactivation of enzyme substrate has been ruled out. A partial characterization of the inhibitor indicates that it is (i) insensitive to ether, trypsin, and phospholipase C; (ii) stable to heat and pH 2-12; and (iii) nondialyzable.
Isadore Brodsky - One of the best experts on this subject based on the ideXlab platform.
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Evidence for copurification of HERV-K-related transcripts and a reverse transcriptase activity in human platelets from patients with essential thrombocythemia.
Blood, 1997Co-Authors: Mark T. Boyd, Brian Foley, Isadore BrodskyAbstract:We have previously reported that particles resembling retroviral particles and possessing an RNA-directed DNA Polymerase activity can be prepared from platelets. Furthermore, we and others have shown that these particles are present at higher levels in patients with essential thrombocythemia and polycythemia vera. We show here that these particles package RNA molecules that encode HERV-K–related pol genes. A subset of the RNA molecules that are packaged are likely to encode the RNA directed DNA Polymerase activity and, because these RNAs possess long/full-length open reading frames for the reverse transcriptase and RNaseH (also for part of the integrase domains in genomic clones) of HERV-K, we propose that these transcripts are indeed strong candidates for encoding the enzyme activity found in these particles. Moreover, by using a modification of the Polymerase chain reaction-based reverse transcriptase assay in which activated DNA is added during cDNA synthesis to suppress DNA Polymerase-mediated RNA-directed DNA synthesis, we have found that the particle-associated enzyme behaves like a retroviral reverse transcriptase, further supporting the conclusion that retrovirus-like, perhaps HERV-K sequences, encode this enzyme activity.
J. A. Levyt - One of the best experts on this subject based on the ideXlab platform.
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Human placentas contain a specific inhibitor of RNA-directed DNA Polymerase (reverse transcriptase/development/retrovirus/RNA-dependent DNA nucleotidyltransferase)
2020Co-Authors: Jay A. Nelson, J. A. Levyt, Joann C. LeongAbstract:Human placental extracts contain a specific in- hibitor of mammalian retroviral RNA-directed DNA Polymerase (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7) activity. This inhibitor copurifies with retrovirus-like particles in human placental extracts. The inhibitor can be re- moved from these particles by salt extraction, which leads to the recovery of the Polymerase activity. Thus, the inhibitor does not irreversibly inactivate the particle-associated RNA-directed DNA Polymerase activity. The inhibitory preparation contained no nu- clease, protease, or phosphatase activity. Because its inhibitory action can be eliminated by the addition of more virus to the re- action, nonspecific inactivation of enzyme substrate has been ruled out. A partial characterization of the inhibitor indicates that it is (i) insensitive to ether, trypsin, and phospholipase C; (ii) stable to heat and pH 2-12; and (iii) nondialyzable.
A. B. Dalen - One of the best experts on this subject based on the ideXlab platform.
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CHARACTERIZATION OF VIRUS-LIKE PARTICLES FROM A PSORIATIC PATIENT WITH RESPECT TO THE POSSIBLE PRESENCE OF PARTICLE-ASSOCIATED RNA AND RNA-directed DNA Polymerase
Acta Pathologica Microbiologica Scandinavica Series B: Microbiology, 2009Co-Authors: Ole-jan Iversen, Jon Nissen-meyer, A. B. DalenAbstract:Subcellular particles resembling retroviruses with respect to their morphology, density, and protein composition, and which are present in the urine of a psoriatic patient have been analysed for the presence of high-molecular-weight polyadenylated RNA and RNA-directed DNA Polymerase activity. Neither RNA-directed DNA Polymerase activity nor high-molecular-weight polyadenylated RNA was detected in preparations containing the purified virus-like particles. This was the case even when the amount of particles analysed exceeded by a factor of 50 or more the amount of avian myeloblastosis virus in which both Polymerase activity and RNA were detected.
