Structural comparison of 26S and 17S ribosomal RNA of yeast.

Abstract

THE two large ribosomal RNA components (26S and 17S rRNA) of yeast exhibit a noteworthy structural similarity as judged by nucleotide composition1, the degree of methylation2, and the extensive cross hybridization with homologous DNA3. Because the 17S rRNA can compete with much more than 50 per cent of 26S rRNA in hybridization with homologous DNA3, and because the estimated chain length of the 26S rRNA is about twice that of 17S rRNA (ref. 4 and R. C. v. d. B., J. Retel and R. J. P., manuscript in preparation), it seems reasonable to assume that the 26S rRNA comprises two segments, each showing some similarity to a 17S rRNA molecule. But although competition in hybridization with DNA does mean that the two RNA species exhibit some primary structural homology, it certainly does not indicate that they have identical base sequences.