The methylated constituents of L cell messenger RNA: evidence for an unusual cluster at the 5' terminus.
An analysis of the methylated constituents of L cell mRNA by a combination of chromatographic methods and enzymatic treatments indicates that they comprise both 2'-O-methyl nucleosides and N6-methyl adenine, and/or 1-methyl adenine, and suggests that the 2'-O-methyl nucleotides, Ym, are part of an unusual class of sequences forming the 5' terminus of mRNA. These sequences seem to contain two 2'-O-methyl residues and a terminal residue that is not phosphorylated but, nevertheless, is blocked with respect to polynucleotid kinase reactivity. A strong candidate is a sequence of the type XppY1mpY2mpZp..., where X represents a blocking group which is itself occasionally methylated. The sequences isolated from total poly(A)+ mRNA contain all four species of 2'-O-methylated nucleoside, indicating some variability among different mRNA species. The methylated sequences do not appear to be enriched in the mRNA which hybridizes with repetitive DNA. The average L cell mRNA molecule also contains three residues of N6-methyl adenine. These residues are not part of the poly(A) segment, but appear to be located internal to the poly(A) near the 3' end of the mRNA molecules.
D000225:Adenine / Q000031:analogs & derivatives / Q000032:analysis; D000241:Adenosine; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002852:Chromatography, Ion Exchange; D007739:L Cells / Q000032:analysis*; D008715:Methionine; D008745:Methylation; D051379:Mice; D009711:Nucleotides / Q000032:analysis*; D009713:Nucleotidyltransferases / Q000378:metabolism; D009841:Oligonucleotides / Q000032:analysis; D011132:Polyribosomes / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis*; D014529:Uridine
D009711:Nucleotides; D009841:Oligonucleotides; D012333:RNA, Messenger; D008715:Methionine; D009713:Nucleotidyltransferases; D000469:Alkaline Phosphatase; D000225:Adenine; D000241:Adenosine; D014529:Uridine