Identification of a small subfraction of hnRNA with the characteristics of a precursor to mRNA.

Adenine Nucleotides/analysis Adenosine Ammonium Sulfate Cell Fractionation Cell Nucleus/analysis Centrifugation, Density Gradient Chromatin/analysis Dactinomycin/pharmacology HeLa Cells/analysis,ultrastructure Humans Polynucleotides/analysis RNA, Messenger/analysis RNA, Neoplasm/analysis,isolation & purification Transcription, Genetic Tritium Uridine

Adenine Nucleotides Chromatin Polynucleotides RNA, Messenger RNA, Neoplasm Tritium Dactinomycin Adenosine Ammonium Sulfate Uridine