U2 spliceosomal RNA

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U2 spliceosomal RNA
Predicted secondary structure and sequence conservation of U2
Symbol U2
Rfam RF00004
Other data
RNA type Gene; snRNA; splicing
Domain(s) Eukaryota
GO 0000370 0045131 0005686
SO 0000392

U2 spliceosomal RNA is a small nuclear RNA (snRNA) component of the spliceosome (involved in pre-mRNA splicing). Complementary binding between U2 snRNA (in an area lying towards the 5' end but 3' to hairpin I) and the branchpoint sequence (BPS) of the intron results in the bulging out of an unpaired adenosine, on the BPS, which initiates a nucleophilic attack at the intronic 5' splice site, thus starting the first of two transesterification reactions that mediate splicing.

Structure and function[edit]

In humans, the U2 spliceosomal RNA is 187 base pairs long, forms five stem-loops, and possesses a 5'-trimethylguanosine five-prime cap. It is able to base-pair extensively with U6 spliceosomal RNA during the splicing process.[1] Bases 33 to 38 are a conserved sequence that base-pairs with the adenosine branch site except for the adenosine itself, forcing the adenosine base to flip out and be exposed. Bases 99 to 105 form the Sm site, around which the heteroheptameric Sm ring is assembled, consisting of consisting of SmB/B', SmD1/2/3, SmE, SmF, and SmG. U6-I and U6-II RNPs bind to stem-loop I. SF3a binds to stem loops IIa and IIb. U2 B″ binds to stem-loop IV, and U2 A' interacts with U2 B″.[2][3]

See also[edit]


  1. ^ Montemayor, Eric J; Curran, Elizabeth C; Liao, Hong Hong; Andrews, Kristie L; Treba, Christine N; Butcher, Samuel E; Brow, David A (18 May 2014). "Core structure of the U6 small nuclear ribonucleoprotein at 1.7-Å resolution". Nature Structural & Molecular Biology 21 (6): 544–551. doi:10.1038/nsmb.2832. Retrieved 17 December 2014. 
  2. ^ Nagai, K; Muto, Y; Pomeranz Krummel, DA; Kambach, C; Ignjatovic, T; Walke, S; Kuglstatter, A (May 2001). "Structure and assembly of the spliceosomal snRNPs. Novartis Medal Lecture.". Biochemical Society transactions 29 (Pt 2): 15–26. PMID 11356120. Retrieved 17 December 2014. 
  3. ^ Stark, Holger; Dube, Prakash; Lührmann, Reinhard; Kastner, Berthold (25 January 2001). "Arrangement of RNA and proteins in the spliceosomal U1 small nuclear ribonucleoprotein particle". Nature 409 (6819): 539–542. doi:10.1038/35054102. Retrieved 17 December 2014. 

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