Kinetic estimation of the base sequence complexity of poly(A)-containing mRNA in Ehrlich-ascites-tumor cells and its abundance in nuclear RNA.

Poly(A)-containing messenger RNA was isolated from polysomes of Ehrlich ascites tumor cells, and analyzed for sequence complexity by hybridization to its complementary DNA. The results indicate the presence of about 27,000 diverse mRNA species in mouse Ehrlich ascites tumor cells. Total nuclear RNA was also hybridized to cDNA transcribed from polysomal poly(A)-containing mRNA up to an rot of 3,000 M . s. It was found that all classes of the polysomal poly(A)-containing mRNA sequences were also present in the nucleus, although the distribution varied. About 2% of the total nuclear RNA sequences were expressed as total polysomal poly(A)-containing mRNA. We also report that the total percentage of the haploid mouse genome transcribed in Ehrlich cells is significantly higher than that found in other mouse cells previously examined for poly(A)-containing mRNA sequence complexity.