Reactome | Lariat Formation and 5'-Splice Site Cleavage

Lariat Formation and 5'-Splice Site Cleavage

Stable Identifier

R-HSA-72143

Type

Reaction [binding]

Species

Homo sapiens

Compartment

nucleoplasm

Synonyms

First step of mRNA splicing

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Lariat Formation and 5'-Splice Site Cleavage

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In the first catalytic step of mRNA splicing, the 2' OH group of the bulged A at the branch site performs a nucleophilic attack on the 5' splice site phosphodiester bond, resulting in cleavage of the bond between the 5' exon and the 5' end of the intron, and formation of a new bond between the 5' end of the intron and the branch site A. This results in a lariat-shaped intermediate, with the intron still attached to the 3' exon. The branch site A has a 2'-5' phosphodiester bond with the G at the beginning of the intron, in addition to the usual 5'-3' and 3'-5'phosphodiester bonds.

Literature References

PubMed ID	Title	Journal	Year
23345524	Rearrangements within human spliceosomes captured after exon ligation Ilagan, JO, Chalkley, RJ, Burlingame, AL, Jurica, MS	RNA	2013
18322460	Isolation of an active step I spliceosome and composition of its RNP core Bessonov, S, Anokhina, M, Will, CL, Urlaub, H, Lührmann, R	Nature	2008
14625303	A simple whole cell lysate system for in vitro splicing reveals a stepwise assembly of the exon-exon junction complex Kataoka, N, Dreyfuss, G	J Biol Chem	2004
6206566	Lariat RNA's as intermediates and products in the splicing of messenger RNA precursors. Padgett, RA, Konarska, MM, Grabowski, PJ, Hardy, SF, Sharp, PA	Science	1984
21526149	Breaking up the C complex spliceosome shows stable association of proteins with the lariat intron intermediate Coltri, P, Effenberger, K, Chalkley, RJ, Burlingame, AL, Jurica, MS	PLoS ONE	2011
6088074	Excision of an intact intron as a novel lariat structure during pre-mRNA splicing in vitro. Ruskin, B, Krainer, AR, Maniatis, T, Green, MR	Cell	1984