title: Mammalian U2 snRNP has a sequence-specific RNA-binding activity.
abstract: The RNA branch formed during pre-mRNA splicing occurs at a wide variety of sequences (branch sites) in different mammalian pre-mRNAs. U2 small nuclear ribonucleoprotein (snRNP) binds to the pre-mRNA branch site following the interaction of a protein, U2AF, with the 3' splice site/polypyrimidine tract. Here we show that despite the variability of mammalian branch sites, U2 snRNP has a sequence-specific RNA-binding activity. Thus, RNA branch formation is regulated by two sequence-specific interactions: U2AF with the 3' splice site/polypyrimidine tract, and U2 snRNP with the branch site. The affinity of the branch site for U2 snRNP affects the efficiency of spliceosome assembly and splicing.
authors.affiliation: Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, Massachusetts 02138.
authors.forename: K K
authors.initials: KK
authors.lastname: Nelson
authors.forename: M R
authors.initials: MR
authors.lastname: Green
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000502:physiology; D006801:Humans; D008969:Molecular Sequence Data; D012322:RNA Precursors / Q000502:physiology; D012342:RNA, Small Nuclear / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid
chemical_list: D012322:RNA Precursors; D012342:RNA, Small Nuclear