B2 RNA and 7SK RNA, RNA polymerase III transcripts, have a cap-like structure at their 5' end.
We found that hydrolysates of poly(A)+ RNA from Ehrlich ascites carcinoma cells which were transcribed by RNA polymerase III contained an unusual component designated as X. It was part of B2 RNA representing a transcript of B2 retroposon, typical of rodents. The component X possesses a cap-like structure, xppp5'G, where x has a non-nucleotide structure. About half of all B2 RNAs contained this group at the 5' end. Previously, Epstein et al. (1) detected a similar structure at the 5' end of small nuclear U6 RNA. Later, Singh and Reddy (2) showed methyl to be the blocking group in the component x of U6 RNA. Besides B2 RNA, we found 5' ends containing methyl groups in 7SK RNA.
Shumyatsky
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GP
Institute of Molecular Biology, USSR Academy of Sciences, Moscow.
Tillib
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SV
Kramerov
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DA
D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000201:enzymology; D002855:Chromatography, Thin Layer; D004591:Electrophoresis, Polyacrylamide Gel; D051379:Mice; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D011061:Poly A / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification; D012313:RNA / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification; D012320:RNA Polymerase III / Q000378:metabolism*; D012333:RNA, Messenger; D012334:RNA, Neoplasm / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification; D014158:Transcription, Genetic
D012333:RNA, Messenger; D012334:RNA, Neoplasm; D011061:Poly A; D012313:RNA; D012320:RNA Polymerase III