Globin mRNA Precursor

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Abstract
The globin mRNA sequences present in duck erythroblast nuclei appear under non-denaturing conditions to be associated with heterogeneous nuclear RNA (hnRNA) molecules of various sizes. Under denaturing conditions, however, the bulk of the globin mRNA sequences associated with hnRNA are released as molecules of size close to that of the active globin mRNA. To find out whether H-bonded structures occur in situ or arise after RNA extraction, nuclei were treated with aminomethyltrioxalen and exposed to UV light. This treatment generates covalent links between opposite strands of double-stranded nucleic acids, which were visualized by EM. After cross-linking, a fraction of the globin mRNA sequences present in nuclei is apparently associated with high MW hnRNA molecules by a link which is resistant to stringent denaturing conditions. In particular, globin mRNA sequences are found associated with a band of approximately 0.9 .times. 106 MW. Within the erythroblast nucleus, globin mRNA sequences may be associated by H-bonds with RNA of high MW. These structures may represent intermediate steps in globin mRNA processing.