title: U1 snRNA directly interacts with polypyrimidine tract-binding protein during splicing repression.
abstract: Splicing of the c-src N1 exon is repressed by the polypyrimidine tract-binding protein (PTB or PTBP1). During exon repression, the U1 snRNP binds properly to the N1 exon 5' splice site but is made inactive by the presence of PTB. Examining the patterns of nuclease protection at this 5' splice site, we find that the interaction of U1 is altered by the adjacent PTB. Interestingly, UV crosslinking identifies a direct contact between the pre-mRNA-bound PTB and the U1 snRNA. EMSA, ITC, and NMR studies show that PTB RRMs 1 and 2 bind the pyrimidine-rich internal loop of U1 snRNA stem loop 4. The PTB/U1 interaction prevents further assembly of the U1 snRNP with spliceosomal components downstream. This precise interaction between a splicing regulator and an snRNA component of the spliceosome points to a range of different mechanisms for splicing regulation.
authors.affiliation: Howard Hughes Medical Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA.
authors.forename: Shalini
authors.initials: S
authors.lastname: Sharma
authors.forename: Christophe
authors.initials: C
authors.lastname: Maris
authors.forename: Frédéric H-T
authors.initials: FH
authors.lastname: Allain
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Black
mesh_terms: D002151:Calorimetry / Q000379:methods; D003432:Cross-Linking Reagents / Q000737:chemistry; D005091:Exons; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008954:Models, Biological; D038941:Polypyrimidine Tract-Binding Protein / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism; D012342:RNA, Small Nuclear / Q000235:genetics*; D012260:Ribonucleases / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D003432:Cross-Linking Reagents; D012333:RNA, Messenger; D012342:RNA, Small Nuclear; C405483:U1 small nuclear RNA; D038941:Polypyrimidine Tract-Binding Protein; D012260:Ribonucleases