title: The U11-48K protein contacts the 5' splice site of U12-type introns and the U11-59K protein.
abstract: Little is currently known about proteins that make contact with the pre-mRNA in the U12-dependent spliceosome and thereby contribute to intron recognition. Using site-specific cross-linking, we detected an interaction between the U11-48K protein and U12-type 5' splice sites (5'ss). This interaction did not require branch point recognition and was sensitive to 5'ss mutations, suggesting that 48K interacts with the 5'ss during the first steps of prespliceosome assembly in a sequence-dependent manner. RNA interference-induced knockdown of 48K in HeLa cells led to reduced cell growth and the inhibition of U12-type splicing, as well as the activation of cryptic, U2-type splice sites, suggesting that 48K plays a critical role in U12-type intron recognition. 48K knockdown also led to reduced levels of U11/U12 di-snRNP, indicating that 48K contributes to the stability and/or formation of this complex. In addition to making contact with the 5'ss, 48K interacts with the U11-59K protein, a protein at the interface of the U11/U12 di-snRNP. These studies provide important insights into the protein-mediated recognition of the U12-type 5'ss, as well as functionally important interactions within the U11/U12 di-snRNP.
authors.affiliation: Institute of Biotechnology, PL 56 Viikinkaari 9, 00014 University of Helsinki, Helsinki, Finland.
authors.forename: Janne J
authors.initials: JJ
authors.lastname: Turunen
authors.forename: Cindy L
authors.initials: CL
authors.lastname: Will
authors.forename: Michael
authors.initials: M
authors.lastname: Grote
authors.forename: Reinhard
authors.initials: R
authors.lastname: Lührmann
authors.forename: Mikko J
authors.initials: MJ
authors.lastname: Frilander
mesh_terms: D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D007438:Introns; D051379:Mice; D034622:RNA Interference; D022821:RNA Splice Sites; D012342:RNA, Small Nuclear / Q000235:genetics / Q000378:metabolism; D017411:Ribonucleoproteins, Small Nuclear / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D017381:Spliceosomes / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D033921:Vesicular Transport Proteins / Q000235:genetics
chemical_list: D051017:Apoptosis Regulatory Proteins; D017931:DNA Primers; C485562:PDCD7 protein, human; D022821:RNA Splice Sites; D012342:RNA, Small Nuclear; D017411:Ribonucleoproteins, Small Nuclear; D014157:Transcription Factors; C552126:U11-U12 small nuclear ribonucleoprotein; D033921:Vesicular Transport Proteins