Differences in nucleotide sequences of ribosomal RNA between the liver and a hepatoma of C3H-He mice.

Abstract

Highly purified ribosomal 18‐S and 28S RNA have been prepared from the liver and the hepatoma (MH 134) of C3H/He mice labeled with 32P and subjected to pancreatic RNAase digestion. Analysis of oligonucleotide patterns with two‐dimensional electrophoresis indicated that there were slight but significant differences between the liver and the hepatoma both for 18‐S and 28‐S RNA. Remarkable was the fact that a tetranucleotide sequence, Y‐(G, G*)‐Cp where G* represents a modified G and Y, an unspecified pyrimidine nucleotide, and a hexanucleotide sequence, Y‐A‐A‐A‐A‐Up that were found in the 18‐S RNA of normal liver were always missing in the 18‐S RNA of the hepatoma.Evidence was also obtained that both 18‐S and 28‐S RNA of these cells are not entirely homogeneous but consist of molecules with some heterogeneity with respect to nucleotide sequences.These results were discussed under the concept of differential transcription of redundant and heterogeneous ribosomal genes in mammalian cells.