THE IDENTIFICATION OF THE RIBOSOMAL RNA CISTRON BY SEQUENCE COMPLEMENTARITY, II. SATURATION OF AND COMPETITIVE INTERACTION AT THE RNA CISTRON

Abstract

The experiments reported offer further evidence for the presence in DNA of a sequence complementary to ribosomal RNA. Saturation experiments suggest that the particular region involved corresponds to between 0.1 and 0.2 per cent of the total genome. Competition for a restricted DNA region can be exhibited by the use of variously labeled homologous ribsosomal RNA. Nonribosomal RNA from the same organism does not compete for the same site. The amount of ribosomal RNA complexed per unit of DNA at saturation suggests a number of repeating, similar, or identical sequences. Further, the density shift of the hybrids suggests that these units are not scattered but contiguous in the DNA structure.