The methylation of transfer and ribosomal ribonucleic acid in human fibroblasts: normal methylation of ribonucleic acid in cystic fibrosis.

A comprehensive study of tRNA and 18 S and 28 S rRNA 
methylation in human fibroblasts is presented. Cells from normal volunteers and 
patients with cystic fibrosis (CF) were examined during exponential growth by 
incubation with L-(methyl-14C)methionine and (3H)uridine. The ratio of 14C to 3H 
counts per minute in isolated RNA serves as a measure of 
the extent of methylation and was found to be similar in 
normal and CF fibroblasts for tRNA, 18 S rRNA, and 28 
S rRNA. Hydrolyzed samples of (14C)-methyl-labeled RNA species were analyzed by 
two dimensional chromatography and autoradiography. The methylated base and nucleoside compositions 
of tRNA and rRNA agree well with data for HeLa cells 
and other eurkaryote cells such as those from yeast, mouse, and 
chicken. RNA methylation patterns in CF fibroblasts were qualitatively and quantitatively 
similar to those observed in normal cells for 4 S, 18 
S, and 28 S RNA. There is no evidence that RNA 
species from patients with cystic fibrosis are deficient in any methylated 
components. Methylation of RNA by tissue-cultured cells from cystic fibrosis is 
qualitatively and quantitatively normal and will not prove to be a 
useful marker for identification of carriers of cystic fibrosis. 