Lariat Formation and 5'-Splice Site Cleavage

Stable Identifier
Reaction [binding]
Homo sapiens
First step of mRNA splicing
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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
18322460 Isolation of an active step I spliceosome and composition of its RNP core

Will, CL, L├╝hrmann, R, Anokhina, M, Bessonov, S, Urlaub, H

Nature 2008
23345524 Rearrangements within human spliceosomes captured after exon ligation

Ilagan, JO, Chalkley, RJ, Jurica, MS, Burlingame, AL

RNA 2013
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.

Sharp, PA, Grabowski, PJ, Hardy, SF, Padgett, RA, Konarska, MM

Science 1984
21526149 Breaking up the C complex spliceosome shows stable association of proteins with the lariat intron intermediate

Coltri, P, Chalkley, RJ, Effenberger, K, Jurica, MS, Burlingame, AL

PLoS ONE 2011
6088074 Excision of an intact intron as a novel lariat structure during pre-mRNA splicing in vitro.

Krainer, AR, Green, MR, Ruskin, B, Maniatis, T

Cell 1984
Orthologous Events
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