Initiator RNA of discontinuous DNA synthesis in human lymphocytes

A short RNA covalently associated with nascent DNA has been isolated after synthesis in vitro with labeled ribonucleoside triphosphates and the removal of DNA by DNAase digestion. The RNA migrates in polyacrylamide gels or chromatographs on DEAE-Sephadex columns as a relatively discrete oligonucleotide 8–11 nucleotides in length. The RNA is associated primarily with nascent DNA with stoichiometry of approximately one per DNA chain. The RNA has a triphosphate group at the 5′ end and 2 or 3 deoxynucleotide residues at the 3′ end that are not removed by DNAase. These results further support a role for the RNA as an initiator of discontinuous DNA synthesis. Examination of sequences present at the 3′ end of the RNA using RNAase to effect transfer of ³²PO₄ from ³²P-labeled DNA to covalently attached RNA indicates that a diverse, rather than unique, set of sequences are present in the RNA.