title: The spliceosome deposits multiple proteins 20-24 nucleotides upstream of mRNA exon-exon junctions.
abstract: Eukaryotic mRNAs exist in vivo as ribonucleoprotein particles (mRNPs). The protein components of mRNPs have important functions in mRNA metabolism, including effects on subcellular localization, translational efficiency and mRNA half-life. There is accumulating evidence that pre-mRNA splicing can alter mRNP structure and thereby affect downstream mRNA metabolism. Here, we report that the spliceosome stably deposits several proteins on mRNAs, probably as a single complex of approximately 335 kDa. This complex protects 8 nucleotides of mRNA from complete RNase digestion at a conserved position 20-24 nucleotides upstream of exon-exon junctions. Splicing-dependent RNase protection of this region was observed in both HeLa cell nuclear extracts and Xenopus laevis oocyte nuclei. Immunoprecipitations revealed that five components of the complex are the splicing-associated factors SRm160, DEK and RNPS1, the mRNA-associated shuttling protein Y14 and the mRNA export factor REF. Possible functions for this complex in nucleocytoplasmic transport of spliced mRNA, as well as the nonsense-mediated mRNA decay pathway, are discussed.
authors: Howard Hughes Medical Institute, Department of Biochemistry, Brandeis University, 415 South Street, Waltham, MA 02454, USA.
authors: H
authors: H
authors: Le Hir
authors: E
authors: E
authors: Izaurralde
authors: L E
authors: LE
authors: Maquat
authors: M J
authors: MJ
authors: Moore
mesh_terms: D000818:Animals; D034961:Antigens, Nuclear; D002467:Cell Nucleus / Q000502:physiology; D003593:Cytoplasm / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism; D005091:Exons; D005260:Female; D006207:Half-Life; D006367:HeLa Cells; D006801:Humans; D034521:Nuclear Matrix-Associated Proteins; D009687:Nuclear Proteins / Q000378:metabolism; D009865:Oocytes / Q000502:physiology; D014176:Protein Biosynthesis; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D016914:Ribonuclease H; D012261:Ribonucleoproteins; D017381:Spliceosomes / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D034521:Nuclear Matrix-Associated Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C084538:RNPS1 protein, human; D012261:Ribonucleoproteins; C111710:SRRM1 protein, human; D016914:Ribonuclease H