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Updated: Aug 4, 2026

Using the E1A Minigene Tool to Study mRNA Splicing Changes
Published on: April 22, 2021
Splicing of U12-type introns deposits an exon junction complex competent to induce nonsense-mediated mRNA decay
Tetsuro Hirose1, Mei-Di Shu, Joan A Steitz
1Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA.
Abstract:
Metazoan cells have two pathways for intron removal involving the U2- and U12-type spliceosomes, which contain mostly nonoverlapping sets of small nuclear ribonucleoproteins. We show that in vitro splicing of a U12-type intron assembles an exon junction complex (EJC) that is comparably positioned and contains many of the same components as that deposited by the U2-type spliceosome. The presence of a U12-type intron downstream of a premature termination codon within an open reading frame (ORF) induces nonsense-mediated decay of the mRNA in vivo. These findings suggest a common pathway for EJC assembly by the two spliceosomes and highlight the evolutionary age of the EJC and its downstream functions in gene expression.
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