title: Mammalian splicing factor SF1 interacts with SURP domains of U2 snRNP-associated proteins.
abstract: Splicing factor 1 (SF1) recognizes the branch point sequence (BPS) at the 3' splice site during the formation of early complex E, thereby pre-bulging the BPS adenosine, thought to facilitate subsequent base-pairing of the U2 snRNA with the BPS. The 65-kDa subunit of U2 snRNP auxiliary factor (U2AF65) interacts with SF1 and was shown to recruit the U2 snRNP to the spliceosome. Co-immunoprecipitation experiments of SF1-interacting proteins from HeLa cell extracts shown here are consistent with the presence of SF1 in early splicing complexes. Surprisingly almost all U2 snRNP proteins were found associated with SF1. Yeast two-hybrid screens identified two SURP domain-containing U2 snRNP proteins as partners of SF1. A short, evolutionarily conserved region of SF1 interacts with the SURP domains, stressing their role in protein-protein interactions. A reduction of A complex formation in SF1-depleted extracts could be rescued with recombinant SF1 containing the SURP-interaction domain, but only partial rescue was observed with SF1 lacking this sequence. Thus, SF1 can initially recruit the U2 snRNP to the spliceosome during E complex formation, whereas U2AF65 may stabilize the association of the U2 snRNP with the spliceosome at later times. In addition, these findings may have implications for alternative splicing decisions.
authors.affiliation: Department of Cell Biology, Faculty of Sciences, University of Geneva, CH-1211 Geneva 4, Switzerland.
authors.forename: Angela
authors.initials: A
authors.lastname: Crisci
authors.affiliation: Department of Cell Biology, Faculty of Sciences, University of Geneva, CH-1211 Geneva 4, Switzerland.
authors.forename: Flore
authors.initials: F
authors.lastname: Raleff
authors.affiliation: Department of Cell Biology, Faculty of Sciences, University of Geneva, CH-1211 Geneva 4, Switzerland.
authors.forename: Ivona
authors.initials: I
authors.lastname: Bagdiul
authors.affiliation: Bioanalytical Mass Spectrometry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany.
authors.forename: Monika
authors.initials: M
authors.lastname: Raabe
authors.affiliation: Bioanalytical Mass Spectrometry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany Bioanalytics, Institute for Clinical Chemistry, University Medical Center Göttingen, D-37075 Göttingen, Germany.
authors.forename: Henning
authors.initials: H
authors.lastname: Urlaub
authors.affiliation: Hybrigenics Services, F-75014 Paris, France.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Rain
authors.affiliation: Department of Cell Biology, Faculty of Sciences, University of Geneva, CH-1211 Geneva 4, Switzerland angela.kraemer@unige.ch.
authors.forename: Angela
authors.initials: A
authors.lastname: Krämer
mesh_terms: D004268:DNA-Binding Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D000072260:RNA Splicing Factors; D016601:RNA-Binding Proteins / Q000378:metabolism; D017413:Ribonucleoprotein, U2 Small Nuclear / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000378:metabolism; D017381:Spliceosomes / Q000378:metabolism; D000072668:Splicing Factor U2AF; D014157:Transcription Factors / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: C410225:CHERP protein, human; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D009687:Nuclear Proteins; D000072260:RNA Splicing Factors; D016601:RNA-Binding Proteins; D017413:Ribonucleoprotein, U2 Small Nuclear; D012261:Ribonucleoproteins; C107467:SF1 protein, human; C484205:SFSWAP protein, human; D000072668:Splicing Factor U2AF; D014157:Transcription Factors; C000607494:U2AF2 protein, human; C088049:splicing factor 3a