title: Studies on reverse transcriptase of RNA tumor viruses. I. Localization of thermolabile DNA polymerase and RNase H activities on one polypeptide.
abstract: Purified reverse transcriptase from avian myeloblastosis virus or Rous sarcoma virus consists of two subunits of average mol wt of 100,000 and 60,000. The lower-molecular-weight subunit, alpha, has been isolated from avian myeloblastosis virus, Rous sarcoma virus and a temperature-sensitive mutant of Rous sarcoma virus, LA337. Subunit alpha manifests both the DNA polymerase and RNase H activities associated with purified reverse transcriptase of avian RNA tumor viruses. The thermal inactivation of these enzymatic activities of alpha subunit from the wild-type virus. The results show that both DNA polymerase and RNase H activities associated with the alpha subunit of LA337 are five to seven times more thermolabile then the corresponding alpha subunit from the wild-type virus. It is concluded that (i) both the polymerase and nuclease activities reside on the same polypeptide chain, and (ii) at least the lower-molecular-weight subunit alpha is coded for by the viral RNA.
mesh_terms: D001354:Avian Leukosis Virus / Q000201:enzymology*; D001358:Avian Sarcoma Viruses / Q000201:enzymology*; D002474:Cell-Free System; D002845:Chromatography; D006160:Guanosine Triphosphate / Q000378:metabolism; D008970:Molecular Weight; D009154:Mutation; D010455:Peptides / Q000032:analysis*; D011119:Polynucleotides / Q000378:metabolism; D012194:RNA-Directed DNA Polymerase / Q000032:analysis* / Q000378:metabolism; D012260:Ribonucleases / Q000032:analysis* / Q000378:metabolism; D013696:Temperature; D014316:Tritium
chemical_list: D010455:Peptides; D011119:Polynucleotides; D014316:Tritium; D006160:Guanosine Triphosphate; D012194:RNA-Directed DNA Polymerase; D012260:Ribonucleases