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.

Identification of discrete polyadenylate-containing RNA components transcribed from HeLa cell mitochondrial DNA

Polyacrylamide gel electrophoresis and sedimentation analysis under denaturing conditions of poly(A)-containing RNA from the polysome region of the sedimentation pattern of a HeLa-cell mitochondrial lysate has revealed the occurrence of a discrete RNA component, which sediments in the native state with a sedimentation constant of about 7 S. From the sedimentation behavior under native and denaturing conditions and the poly(A) content, a molecular weight of about 9 x 10(4) has been estimated for this component. RNA.DNA hybridization experiments have indicated that this component is coded for by the light strand of mitochondrial DNA. Evidence for the occurrence of a poly(A)-containing RNA component sedimenting at about 9 S and coded for by the heavy strand has also been obtained.