Transcription of DNA from the 70 S RNA of Rous Sarcoma Virus I. Identification of a Specific 4 S RNA Which Serves as Primer

Abstract

The enzymatic transcription of DNA from the 70 S RNA of Rous sarcoma virus (RSV) is initiated on the 3′ terminus of a molecule of 4 S RNA which is hydrogen bonded to the viral genome. We labeled this primer with radioactive deoxynucleotides, and demonstrated that its release from 70 S RNA by thermal denaturation was accompanied by a reduction in the template activity of the viral RNA. Two-dimensional electrophoresis in polyacrylamide gels separated the 4 S RNAs associated with the 70 S RNA of RSV into approximately eight fractions, each of which appeared to contain a discrete species of tRNA. The RNA in one of these fractions served as the principal primer for initiation of DNA synthesis by both detergent-disrupted virions of RSV and purified RNA-directed DNA polymerase with RSV 70 S RNA as template.