Complex population of mRNA sequences in large polyadenylylated nuclear RNA molecules.
Polyadenylylated heterogeneous nuclear RNA [poly(A)-hnRNA] from mouse brain was subjected to electrophoresis in agarose gels containing CH3HgOH, and molecules larger than 8 kilobases or 13 kilobases were recovered. cDNA was then transcribed from polyadenylylated RNA fragments cleaved from these large molecules. The resulting cDNA hybridized almost to completion with poly(A)-mRNA isolated from mouse brain polysomes. From the hybridization kinetics of this cDNA with its template RNA, it was estimated that the sequence complexity of the 3'-proximal sequences (of the same average size as mRNA) of the greater than 8 kilobase poly(A)-hnRNA was about 57,000 kilobases. The sequence complexity of poly(A)-mRNA, estimated from the template-driven hybridization kinetics of its respective cDNA, was about 110,000 kilobases. It is concluded that most, if not all, of the 3'-proximal sequences of large poly(A)-hnRNA molecules are homologous with mRNA in the mouse brain and that at least 40,000 different mRNA sequences (or portions of mRNA sequences) are represented in the 3'-proximal sequences of greater than 8 kilobase poly(A)-hnRNA.
D000818:Animals; D001923:Brain Chemistry; D002467:Cell Nucleus / Q000032:analysis*; D007700:Kinetics; D051379:Mice; D009693:Nucleic Acid Hybridization; D011061:Poly A / Q000032:analysis*; D012332:RNA, Heterogeneous Nuclear / Q000302:isolation & purification; D012333:RNA, Messenger / Q000302:isolation & purification; D014158:Transcription, Genetic
D012332:RNA, Heterogeneous Nuclear; D012333:RNA, Messenger; D011061:Poly A