Studies on the Heterogeneity of Mouse-Globin Messenger RNA.

Mouse reticulocyte messenger (9-S) RNA has been prepared by treatment of polysomes with sodium dodecylsulphate. On 6% polyacrylamide gels, two sharp and one more diffuse component can be resolved in the 9-S region, Messenger RNA prepared from 14-S mRNA. protein from EDTA-treated polysomes contains only the diffuse component. This component has priming activity for both α- and β-globin chains, and evidence is presented that it can be partially resolved into separate messengers for each chain. The two sharp components, which migrate more slowly than the globin mRNA, are associated with the 30-S ribosomal subunit after EDTA treatment, have no translational activity in a duck reticulocyte cell-free protein-synthesis system, and (unlike the diffuse component) are not destroyed by gentle sonication of polysomes to monosomes. The non-coding components comprise approximately one-third of the RNA in the 9-S region of most RNA preparations from mouse reticulocytes. The diffuse (coding) 9-S component from 14-S mRNA · protein runs as a sharp symmetrical peak in formamide-acrylamide gel electrophoresis, suggesting that there may be variation in secondary structure in aqueous solution rather than in molecular weight. [ABSTRACT FROM AUTHOR]