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Sequential methylation of globin mRNA in nucleated erythroid cells and reticulocytes of mice
The order of methylation of the 5'-terminus of globin mRNA of mice was studied by incubation of staged nucleated erythroid cells and peripheral reticulocytes with [methyl-3H] methionine. Methylation of the 5'-termini of alpha and beta- globin mRNAs in enucleated reticulocytes was demonstra...
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Published in: | The Journal of biological chemistry 1978-01, Vol.253 (1), p.246-251 |
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Main Authors: | , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | The order of methylation of the 5'-terminus of globin mRNA of mice was studied by incubation of staged nucleated erythroid
cells and peripheral reticulocytes with [methyl-3H] methionine. Methylation of the 5'-termini of alpha and beta- globin mRNAs
in enucleated reticulocytes was demonstrated as follows: (a) [methyl-3H] incorporation into poly(A)+ RNA of reticulocytes
co-migrated with the alpha- and beta- globin mRNAs on gel electrophoresis, and (b) following digestion of this RNA, radioactivity
was localized to the four methyl sites at the 5'-capped structure of mouse globin mRNAs. However, this methylation is only
5 to 8% as efficient as in nucleated erythroid precursor cells, suggesting that most globin mRNA molecules are fully methylated
prior to the reticulocyte stage. Incubations of early and late nucleated erythroid precursor cells and pulse-chase experiments
with reticulocytes demonstrate that addition of the four 5'-terminal methyl groups follows an orderly sequence. In addition,
the pulse-chase experiments suggest the turnover of the N7-methyl group on the 5'-terminal guanosine, but not of the other
methyl groups in the 5'-terminus of globin mRNA. Thus, 5'-terminal methylation of globin mRNA is a nonrandom, dynamic process. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(17)38296-0 |