Pre-mRNA splicing alters mRNP composition: evidence for stable association of proteins at exon–exon junctions
Abstract
We provide direct evidence that pre-mRNA splicing alters mRNP protein composition. Using a novel in vitro cross-linking approach, we detected several proteins that associate with mRNA exon–exon junctions only as a consequence of splicing. Immunoprecipitation experiments suggested that these proteins are part of a tight complex around the junction. Two were identified as SRm160, a nuclear matrix-associated splicing coactivator, and hPrp8p, a core component of U5 snRNP and spliceosomes. Glycerol gradient fractionation showed that a subset of these proteins remain associated with mRNA after its release from the spliceosome. These results demonstrate that the spliceosome can leave behind signature proteins at exon–exon junctions. Such proteins could influence downstream metabolic events in vivo such as mRNA transport, translation, and nonsense-mediated decay.
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Footnotes
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↵3 Corresponding authors.
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E-MAIL mmoore{at}brandeis.edu; FAX (781) 736-2337.
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E-MAIL maquat{at}sc3101.med.buffalo.edu; FAX (716) 845-8449.
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- Received January 26, 2000.
- Accepted March 23, 2000.
- Cold Spring Harbor Laboratory Press
