Yamaura I, Cavalieri L F
J Virol. 1976 Apr;18(1):26-33. doi: 10.1128/JVI.18.1.26-33.1976.
The synthesis of DNA on avian myeloblastosis virus (AMV) RNA as the primer-template using AMV reverse transcriptase in vitro has been examined as a function of the concentrations of these components, as well as a function of the ionic strenth of the assay medium. The results are consistent with the hypothesis that two types of sites exist on the AMV RNA: inactive "dead-end" sites that merely bind the enzyme, and active binding sites that lead to DNA synthesis. Velocity sedimentation studies of reverse transcriptase reveal that the enzyme becomes a dimer (or oligomer) at low salt concentrations and it is at these concentrations that the two types of sites are evident on the RNA. At high salt concentration the enzyme, which exists primarily as a monomer, is inactive with AMV RNA, although it is active when poly(rA)dT10 is used as the primer-template. We have shown that inactive sites are not due to binding of the reverse transcriptase to nicked regions or to partially denatured RNA molecules. We deduce that inactive sites are those containing incorrect 4S primer molecules. These results are discussed in terms of the mechanism of the interaction of the reverse transcriptase with AMV RNA.
在体外，以禽成髓细胞瘤病毒（AMV）RNA作为引物-模板，利用AMV逆转录酶合成DNA，已作为这些组分浓度的函数以及测定介质离子强度的函数进行了研究。结果与以下假设一致：AMV RNA上存在两种类型的位点，即仅结合酶的无活性“死端”位点和导致DNA合成的活性结合位点。对逆转录酶的速度沉降研究表明，该酶在低盐浓度下会形成二聚体（或寡聚体），正是在这些浓度下，RNA上的两种类型位点才明显可见。在高盐浓度下，主要以单体形式存在的该酶对AMV RNA无活性，尽管当使用聚（rA）dT10作为引物-模板时它是有活性的。我们已经表明，无活性位点并非由于逆转录酶与切口区域或部分变性的RNA分子结合所致。我们推断，无活性位点是那些含有不正确的4S引物分子的位点。根据逆转录酶与AMV RNA相互作用的机制对这些结果进行了讨论。
