title: Factors associated with a purine-rich exonic splicing enhancer sequence in Xenopus oocyte nucleus.
abstract: Purine-rich exonic splicing enhancers (ESEs) stimulate splicing of the adjacent introns with suboptimal splice sites. To elucidate the mechanism regarding ESEs, factors specifically associated with ESEs in HeLa cell nuclear extracts were previously investigated, and shown to include SR (serine/arginine-rich) proteins. However, factors associated with ESEs in vivo have not yet been explored. Here we show that a GAA repeat RNA sequence, a typical ESE, is associated in Xenopus oocyte nuclei with at least one SR protein, SF2/ASF, as was expected. Moreover, components of SF3a/b complexes, U2 snRNA, and U2AF(65) were also found to be associated with the ESE in the nucleus. Since SF3a/b complexes are the constituents of the 17S U2 snRNP, these results suggest that the 17S U2 snRNP is associated with the ESE in the nucleus, probably through bridging interactions of U2AF and SR proteins. The identified factors may represent a functional splicing enhancer complex in vivo.
authors.affiliation: Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan and CREST, JST, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Masuyama
authors.forename: Ichiro
authors.initials: I
authors.lastname: Taniguchi
authors.forename: Katsuya
authors.initials: K
authors.lastname: Okawa
authors.forename: Mutsuhito
authors.initials: M
authors.lastname: Ohno
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000235:genetics* / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D005091:Exons / Q000235:genetics*; D008957:Models, Genetic; D009687:Nuclear Proteins / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism*; D011485:Protein Binding; D012326:RNA Splicing / Q000235:genetics*; D012342:RNA, Small Nuclear / Q000235:genetics; D011983:Receptors, Purinergic / Q000235:genetics*; D012261:Ribonucleoproteins / Q000378:metabolism; D000072668:Splicing Factor U2AF; D014982:Xenopus laevis / Q000235:genetics* / Q000378:metabolism
chemical_list: D009687:Nuclear Proteins; D012342:RNA, Small Nuclear; D011983:Receptors, Purinergic; D012261:Ribonucleoproteins; D000072668:Splicing Factor U2AF