title: Bimolecular exon ligation by the human spliceosome.
abstract: Intron excision is an essential step in eukaryotic gene expression, but the molecular mechanisms by which the spliceosome accurately identifies splice sites in nuclear precursors to messenger RNAs (pre-mRNAs) are not well understood. A bimolecular assay for the second step of splicing has now revealed that exon ligation by the human spliceosome does not require covalent attachment of a 3' splice site to the branch site. Furthermore, accurate definition of the 3' splice site in this system is independent of either a covalently attached polypyrimidine tract or specific 3' exon sequences. Rather, in this system 3' splice site selection apparently occurs with a 5' --> 3' directionality.
authors.affiliation: W. M. Keck Institute for Cellular Visualization, Department of Biochemistry, Brandeis University, Waltham, MA 02254, USA.
authors.forename: K
authors.initials: K
authors.lastname: Anderson
authors.forename: M J
authors.initials: MJ
authors.lastname: Moore
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites; D005091:Exons; D006801:Humans; D007438:Introns; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism*; D012326:RNA Splicing; D017381:Spliceosomes / Q000378:metabolism*
chemical_list: D012322:RNA Precursors