A novel U2 and U11/U12 snRNP protein that associates with the pre-mRNA branch site

Cindy L. Will, Claudia Schneider, Andrew M. Macmillan, Nikos F. Katopodis, Gitte Neubauer, Matthias Wilm, Reinhard Lührmann, Charles C. Query

Research output: Contribution to journalArticlepeer-review

132 Scopus citations


Previous UV cross-linking studies demonstrated that, upon integration of the U2 snRNP into the spliceosome, a 14 kDa protein (p14) interacts directly with the branch adenosine, the nucleophile for the first transesterification step of splicing. We have identified the cDNA encoding this protein by microsequencing a 14 kDa protein isolated from U2-type spliceosomes. This protein contains an RNA recognition motif and is highly conserved across species. Antibodies raised against this cDNA-encoded protein precipitated the 14 kDa protein cross-linked to the branch adenosine, confirming the identity of the p14 cDNA. A combination of immunoblotting, protein microsequencing and immunoprecipitation revealed that p14 is a component of both 17S U2 and 18S U11/U12 snRNPs, suggesting that it contributes to the interaction of these snRNPs with the branch sites of U2-and U12-type pre-mRNAs, respectively. p14 was also shown to be a subunit of the heteromeric splicing factor SF3b and to interact directly with SF3b155. Immunoprecipitations indicated that p14 is present in U12-type spliceosomes, consistent with the idea that branch point selection is similar in the major and minor spliceosomes.

Original languageEnglish (US)
Pages (from-to)4536-4546
Number of pages11
JournalEMBO Journal
Issue number16
StatePublished - Aug 15 2001


  • Branch site
  • Pre-mRNA splicing
  • RRM
  • U11
  • U12 snRNP
  • U2 snRNP

ASJC Scopus subject areas

  • General Neuroscience
  • Molecular Biology
  • General Biochemistry, Genetics and Molecular Biology
  • General Immunology and Microbiology


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