Common name:
CA index name:
1H-Purinium, 2-(dimethylamino)- 6,9-dihydro-7-methyl-6-oxo- 9-b-D-ribofuranosyl-
CA registry numbers:
ribonucleoside 40027-70-1
base not assigned
elemental composition:
nucleoside mass:
Source type phylogenetic source
archaea bacteria eukarya
mRNA [1]viral [2]
Comment: This 5'-cap nucleoside is joined to the RNA through
a unique triphosphate bridge [Gp(5'-5')ppNp...]. This nucleoside is rare in mRNA.
snRNA [3]
Comment: The m#2#,#2#,#7G cap nucleoside is also found in U3 RNA from the nucleolus.
For review of the trimethylguanosine cap structures see [6]

Structure: [3]

Synthesis: [3]

Comment: The structure was first assigned using material from 2-10S RNA from Chinese hamster ovary cells [3], and later from snRNA from Novikoff hepatoma ascites cells [4]. More rigorous characterization of the synthetic nucleoside used for comparison is given in [5].


  1. Liou, R. and Blumenthal, T. (1990) Mol. Cell Biol., 10, 1764-1768.
  2. Hsu-Chen, C.C. and Dubin, D.T. (1976) Nature, 264, 190-191.
  3. Saponara, A.G. and Enger, M.D. (1969) Nature, 223, 1365-1366.
  4. Reddy, R., Ro-Choi, T.S., Henning, D., Shibata, H., Choi, Y.C. and Busch, H. (1972) J. Biol. Chem., 247, 7245-7250.
  5. Ro-Choi, T.S., Choi, Y.C., Henning, D., McCloskey, J.A. and Busch, H. (1975) J. Biol. Chem., 250, 3921-3928.
  6. Ro-Choi, T.S. (1999) Crit. Rev. Eukaryot. Gene Expr., 9, 107-158.