Evidence for the function of an exonic splicing enhancer after the first catalytic step of pre-mRNA splicing

Shern L. Chew, Hong Xiang Liu, Akila Mayeda, Adrian R. Krainer

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46 Citations (Scopus)


Exonic splicing enhancers (ESEs) activate premRNA splicing by promoting the use of the flanking splice sites. They are recognized by members of the serine/arginine-rich (SR) family of proteins, such as splicing factor 2/alternative splicing factor (SF2/ASF), which recruit basal splicing factors to form the initial complexes during spliceosome assembly. The in vitro splicing kinetics of an ESE-dependent IgM pre-mRNA suggested that an SF2/ASF- specific ESE has additional functions later in the splicing reaction, after the completion of the first catalytic step. A bimolecular exon ligation assay, which physically uncouples the first and second catalytic steps of splicing in a trans-splicing reaction, was adapted to test the function of the ESE after the first step. A 3' exon containing the SF2/ASF-specific ESE underwent bimolecular exon ligation, whereas 3' exons without the ESE or with control sequences did not. The ESE-dependent trans-splicing reaction occurred after inactivation of U1 or U2 small nuclear ribonucleoprotein particles, compatible with a functional assay for events after the first step of splicing. The ESE-dependent step appears to take place before the ATP- independent part of the second catalytic step. Bimolecular exon ligation also occurred in an S100 cytosolic extract, requiring both the SF2/ASF-dependent ESE and complementation with SF2/ASF. These data suggest that some ESEs can act late in the splicing reaction, together with appropriate SR proteins, to enhance the second catalytic step of splicing.

Original languageEnglish
Pages (from-to)10655-10660
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number19
Publication statusPublished - 14-09-1999
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General


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