Globin mRNA sequences in polyadenylated and nonpolyadenylated nuclear precursor-messenger RNA from avian erythroblasts.

Nuclear RNA from immature duck erythrocytes was fractionated into polyadenylated and nonpolyadenylated fractions, and globin mRNA sequences were determined by hybridization to DNA complementary to globin mRNA. 80--90% of labeled nuclear RNA is found to be nonpolyadenylated, and 70--80% of the globin mRNA sequences present in the nucleus are found in nonpolyadenylated molecules. These data suggest that polyadenylation does not specifically select for globin mRNA sequences. The nonpolyadenylated globin mRNA sequences present in the nucleus are found mostly in molecules of small size, close to the size of polyribosomal globin mRNA, suggesting that polyadenylation is a later event in globin mRNA formation.