TY - JOUR
T1 - Sequential methylation of globin mRNA in nucleated erythroid cells and reticulocytes of mice.
AU - Cheng, T.
AU - Kazazian, H. H.
N1 - Copyright:
Medline is the source for the citation and abstract of this record.
PY - 1978/1/10
Y1 - 1978/1/10
N2 - 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.
AB - 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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M3 - Article
C2 - 618861
AN - SCOPUS:0018264495
SN - 0021-9258
VL - 253
SP - 246
EP - 251
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 1
ER -