scholarly journals Methylated nucleotide sequences in HeLa-cell ribosomal ribonucleic acid. Correlation between the results from ‘fingerprinting’ hydrolysates obtained by digestion with T1 ribonuclease and with T1 plus pancreatic ribonuclease

1977 ◽  
Vol 167 (1) ◽  
pp. 211-221 ◽  
Author(s):  
B E H Maden ◽  
M S N Khan
Keyword(s):  
Hela Cell ◽  
Ribonucleic Acid ◽  
Quantitative Description ◽  
Nucleotide Sequences ◽  
Enzymic Digestion ◽  
Pancreatic Ribonuclease ◽  
Qualitative And Quantitative ◽  
Ribosomal Ribonucleic Acid

The methylated nucleotide sequences in HeLa-cell rRNA were previously characterized after enzymic digestion of the rRNA by T1 ribonuclease alone or by combined T1 plus pancreatic ribonucleases. For any methylated product occurring in a T1-ribonuclease digest there must be one or more corresponding products in a combined T1-plus-pancreatic-ribonuclease digest. Here we correlate fully the inter-relationship between the methylated products occurring in the two digestion systems. The analysis has led to the resolution of some previous uncertainties and has permitted an almost complete qualitative and quantitative description of the methylated components in HeLa-cell rRNA. The data are compared with those reported by other authors for HeLa-cell rRNA.

scholarly journals Biosynthesis of a hypermodified nucleotide in Saccharomyces carlsbergensis 17S and HeLa-cell 18S ribosomal ribonucleic acid

1978 ◽  
Vol 169 (1) ◽  
pp. 71-77 ◽  
Author(s):  
R C Brand ◽  
J Klootwijk ◽  
R J Planta ◽  
B E H Maden
Keyword(s):  
Hela Cell ◽  
Hela Cells ◽  
Ribonucleic Acid ◽  
18S Rrna ◽  
Saccharomyces Carlsbergensis ◽  
Ribosomal Ribonucleic Acid ◽  
Precursor Molecules

The biosynthesis of a hypermodified nucleotide, similar to or identical with 3-(3-amino-3-carboxypropyl)-1-methylpseudouridine monophosphate, present in Saccharomyces carlsbergensis 17S and HeLa-cell 18S rRNA, was investigated with respect to the sequence of reactions required for synthesis and their timing in ribosome maturation. In both yeast and HeLa cells methylation precedes attachment of the 3-amino-3-carboxypropyl group. In yeast the methylated precursor nucleotide was tentatively characterized as 1-methylpseudouridine. This precursor nucleotide was demonstrated in both 37S and most of the cytoplasmic 18S pre-rRNA (rRNA precursor) molecules. The synthesis of the hypermodified nucleotide is completed just before the final cleavage of 18S pre-rRNA to give 17S rRNA, so that the final addition of the 3-amino-3-carboxypropyl group is a cytoplasmic event. Comparable experiments with HeLa cells indicated that formation of 1-methylpseudouridine occurs at the level of 45S RNA and addition of the 3-amino-3-carboxypropyl group occurs in the cytoplasm on newly synthesized 18S RNA.

scholarly journals Differences in the patterns of methylation in rat liver ribosomal ribonucleic acid after reaction in vivo with methyl methanesulphonate and NN-dimethylnitrosamine

1972 ◽  
Vol 129 (3) ◽  
pp. 519-528 ◽  
Author(s):  
P. J. O'Connor ◽  
M. J. Capps ◽  
A. W. Craig ◽  
P. D. Lawley ◽  
S. A. Shah
Keyword(s):  
Rat Liver ◽  
Alkaline Hydrolysis ◽  
Ribonucleic Acid ◽  
Significant Feature ◽  
Enzymic Digestion ◽  
Short Intervals ◽  
Ribosomal Ribonucleic Acid ◽  
Methylating Agents ◽  
Hydrolysis Of

1. rRNA was isolated from rat liver at short intervals after the intraperitoneal injection of [14C]methyl methanesulphonate (50mg/kg) or NN-di[14C]methylnitrosamine (2mg/kg). These doses were chosen to minimize the effects of toxicity. 2. The following methods of hydrolysis of [14C]methylated rRNA were employed: enzymic digestion to nucleosides at pH8; alkaline hydrolysis and conversion into nucleosides; acid hydrolysis to bases. 3. The methylation products were analysed by chromatography on columns of Dowex-50 (H+ form) and Dowex-50 (NH4+ form). 4. With both methylating agents the principal product of methylation was 7-methylguanine. Differences were obtained, however, in the molar proportions of the minor bases 3-methylcytosine, 1-methyladenine and 7-methyladenine. Methylation at the O-6 position of guanine was a significant feature of rRNA obtained from the NN-di[14C]methylnitrosamine-treated animals but was not detected in rRNA after treatment with [14C]methyl methanesulphonate.

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