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.
RNA | 16S ribosomal RNA | RNA polymerase | RNA polymerase II | RNA-dependent RNA polymerase | RNA virus | RNA interference | RNA-binding protein | non-coding RNA | Transfer RNA | RNA-Seq | RNA polymerase III | RNA polymerase I | messenger RNA | U2 spliceosomal RNA | small nuclear RNA | RNA splicing | 18S ribosomal RNA | Z12 small nucleolar RNA | transfer RNA | Small nucleolar RNA R43 | RNA Tie Club | Polynucleobacter-1 RNA motif | NoRC associated RNA | Non-coding RNA | Messenger RNA | List of RNA structure prediction software | FnrS RNA | CopA-like RNA | 5S ribosomal RNA |
Small Cajal body-specific RNA 17 (also known as U12-22 scaRNA) 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.
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.