small Cajal body-specific RNA 18 | |
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Identifiers | |
Symbol | SCARNA18 |
Alt. Symbols | U91 |
Rfam | RF00283 |
Other data | |
RNA type | Gene; snRNA; snoRNA; scaRNA |
Domain(s) | Eukaryota |
GO | GO:0006396 GO:0015030 GO:0005730 |
SO | SO:0000275 |
PDB structures | PDBe |
small Cajal body-specific RNA 18 (also known as U91 or U4-8) is a type of small nuclear RNA which localises to the cajal bodies and proposed to guide the modification of RNA polymerase II transcribed spliceosomal RNAs U1, U2, U4, U5 and U12. [1]
This snoRNA U91 appears to be belong to the C/D box class of snoRNAs. [2] It was identified by Darzacq [1] and is predicted to guide the 2'O-ribose methylation of U4 snRNA C8. This C/D domain was later found associated in tandem with another C/D box domain U12-22. Both the doublet (U12-22/U4-8) and singlet (U4-8) forms of this snRNA have been purified from Hela cells. [1] The doublet form U12-22/U4-8 has been shown to localise to the nucleoplasm and is proposed to reside in the Cajal bodies whereas the U4-8 single domain appears to accumulate in the nucleolus. [3] In humans the genomic location of U12-88/U4-8 is intergenic and the purified transcript has been shown to possess a methylated guanosine cap suggesting it is independently transcribed by RNA pol II. [3]