title: A downstream splicing enhancer is essential for in vitro pre-mRNA splicing.
abstract: Splicing enhancers have previously been shown to promote processing of introns containing weak splicing signals. Here, we extend these studies by showing that also 'strong' constitutively active introns are absolutely dependent on a downstream splicing enhancer for activity in vitro. SR protein binding to exonic enhancer elements or U1 snRNP binding to a downstream 5' splice site serve redundant functions as activators of splicing. We further show that a 5' splice site is most effective as an enhancer of splicing. Thus, a 5' splice site is functional in S100 extracts, under conditions where a SR enhancer is nonfunctional. Also, splice site pairing occurs efficiently in the absence of exonic SR enhancers, emphasizing the significance of a downstream 5' splice site as the enhancer element in vertebrate splicing.
authors.affiliation: Dept. of Medical Biochemistry and Microbiology, Uppsala University, Sweden.
authors.forename: B G
authors.initials: BG
authors.lastname: Yue
authors.forename: G
authors.initials: G
authors.lastname: Akusjärvi
mesh_terms: D000260:Adenoviruses, Human / Q000235:genetics*; D000818:Animals; D004330:Drosophila / Q000235:genetics; D029721:Drosophila Proteins; D004742:Enhancer Elements, Genetic; D051717:Fushi Tarazu Transcription Factors; D017344:Genes, Insect; D005814:Genes, Viral; D006367:HeLa Cells; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D007438:Introns; D009687:Nuclear Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D012322:RNA Precursors; D012326:RNA Splicing; D016601:RNA-Binding Proteins; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000378:metabolism; D000068103:Serine-Arginine Splicing Factors
chemical_list: D029721:Drosophila Proteins; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D012322:RNA Precursors; D016601:RNA-Binding Proteins; D017412:Ribonucleoprotein, U1 Small Nuclear; C497169:ftz protein, Drosophila; D000068103:Serine-Arginine Splicing Factors