title: The recruitment of the U5 snRNP to nascent transcripts requires internal loop 1 of U5 snRNA.
abstract: In this study, we take advantage of the high spatial resolution offered by the nucleus and lampbrush chromosomes of the amphibian oocyte to investigate the mechanisms that regulate the intranuclear trafficking of the U5 snRNP and its recruitment to nascent transcripts. We monitor the fate of newly assembled fluorescent U5 snRNP in Xenopus oocytes depleted of U4 and/or U6 snRNAs and demonstrate that the U4/U6.U5 tri-snRNP is not required for the association of U5 snRNP with Cajal bodies, splicing speckles, and nascent transcripts. In addition, using a mutational analysis, we show that a non-functional U5 snRNP can associate with nascent transcripts, and we further characterize internal loop structure 1 of U5 snRNA as a critical element for licensing U5 snRNP to target both nascent transcripts and splicing speckles. Collectively, our data support the model where the recruitment of snRNPs onto pre-mRNAs is independent of spliceosome assembly and suggest that U5 snRNP may promote the association of the U4/U6.U5 tri-snRNP with nascent transcripts.
authors.affiliation: Department of Cell and Developmental Biology, University of Illinois at Champaign-Urbana, 601 S Goodwin Avenue, Room B107 CLSL, Urbana, IL 61801, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Kim
authors.forename: Joshua
authors.initials: J
authors.lastname: Paschedag
authors.forename: Natalya
authors.initials: N
authors.lastname: Novikova
authors.forename: Michel
authors.initials: M
authors.lastname: Bellini
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D020541:Coiled Bodies / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D008969:Molecular Sequence Data; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism; D012326:RNA Splicing; D012342:RNA, Small Nuclear / Q000235:genetics* / Q000378:metabolism; D017414:Ribonucleoprotein, U4-U6 Small Nuclear / Q000235:genetics / Q000378:metabolism; D017415:Ribonucleoprotein, U5 Small Nuclear / Q000235:genetics* / Q000378:metabolism; D017381:Spliceosomes / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014981:Xenopus / Q000235:genetics
chemical_list: D012322:RNA Precursors; D012342:RNA, Small Nuclear; D017414:Ribonucleoprotein, U4-U6 Small Nuclear; D017415:Ribonucleoprotein, U5 Small Nuclear; C405485:U5 small nuclear RNA; C405486:U6 small nuclear RNA