Large globin RNA molecules and their processing.

RNA containing beta-globin message sequences larger than 2000 nucleotides could be detected in nuclei of murine erythroid cells using cloned beta-globin cDNA. Under steady-state conditions, when nuclear RNA was separated on denaturing agarose gels and covalently bound to diazobenzyloxymethyl-paper, a 4200-nucleotide and a approximately equal to 3500-nucleotide band could be seen. The presence of these large molecules could also be visualized under the electron microscope after hybridization to a beta-globin genomic DNA fragment. We suggest that these molecules are precursors to mature mRNAs. In addition to these large molecules, a series of molecules smaller than 2000 nucleotides were seen. These are postulated to be processing intermediates in the maturation of beta-globin mRNA.