Pyrimidine Clusters on the Transcribing Strand of DNA and Their Possible Role in the Initiation of RNA Synthesis

Abstract

Little is known at present about the details of the molecular mechanism of the DNA-to-RNA transcription process, including some of its unique properties, as discussed in the preceding article: preferential initiation of RNA molecules with purine bases and asymmetric copying of only one of the two DNA strands (Maitra, Cohen, and Hurwitz, this volume; Maitra and Hurwitz, 1965). Both of these features might be better understood if DNA molecules could be shown to contain on their transcribing strands some special base sequences serving as initiation points for RNA synthesis, and containing the pyrimidine bases complementary to the purines on the 5′ termini of the RNA.