Polyadenylic acid sequences in the heterogeneous nuclear RNA and rapidly-labeled polyribosomal RNA of HeLa cells: possible evidence for a precursor relationship.

Polyadenylate sequences have been found covalently linked in heterogeneous DNA-like nuclear RNA of HeLa cells. This poly(A) material seems homogeneous in size and accounts for about 0.5% of such RNA. Similar poly(A) sequences were found in rapidly-labeled polyribosomal RNA, thought to be messenger RNA. A possible model for mRNA synthesis from large heterogeneous nuclear RNA precursor molecules is discussed.