title: A single subunit from avian myeloblastosis virus with both RNA-directed DNA polymerase and ribonuclease H activity.
abstract: Two structurally distinct forms of RNA-directed DNA polymerase from avian myeloblastosis virus were resolved by chromatography on phosphocellulose and purified. In addition to RNA-directed DNA polymerase activity, both enzymes had ribonuclease H (RNase H) activity, which degraded the RNA moiety of RNA.DNA hybrids. As determined by sodium dodecyl sulfate-polyacrylamide disc-gel electrophoresis, one form had two subunits, alpha (alpha) and beta (beta), with molecular weights of 65,000 and 105,000, respectively. The other had a single subunit, alpha, with a molecular weight of 65,000. The sedimentation coefficients of alphabeta and alpha, determined by glycerol gradient centrifugation in 0.35 M KCl, were 7.8 S and 5.2 S, respectively. Both enzymes had similar antigenic determinants and could not be distinguished by a differential response to several different RNA and DNA templates. We suggest that alpha, which contains both RNA-directed DNA polymerase and RNase H activity, is derived by dissociation of alphabeta; the function of the beta subunit is unknown.
mesh_terms: D001354:Avian Leukosis Virus / Q000201:enzymology*; D002247:Carbon Isotopes; D002499:Centrifugation, Density Gradient; D002848:Chromatography, DEAE-Cellulose; D004247:DNA / Q000378:metabolism; D004279:DNA, Viral / Q000096:biosynthesis; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes; D007118:Immunoassay; D008970:Molecular Weight; D009693:Nucleic Acid Hybridization; D011119:Polynucleotides / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism; D012194:RNA-Directed DNA Polymerase / Q000302:isolation & purification / Q000378:metabolism*; D012260:Ribonucleases / Q000302:isolation & purification / Q000378:metabolism*; D013698:Templates, Genetic; D013950:Thymus Gland / Q000032:analysis
chemical_list: D002247:Carbon Isotopes; D004279:DNA, Viral; D000939:Epitopes; D011119:Polynucleotides; D012367:RNA, Viral; D004247:DNA; D012194:RNA-Directed DNA Polymerase; D012260:Ribonucleases