title: Overexpression of the arginine-rich carboxy-terminal region of U1 snRNP 70K inhibits both splicing and nucleocytoplasmic transport of mRNA.
abstract: Transient transfection of the U1 snRNP 70K protein into COS cells induced nuclear reorganization and redistribution of the splicing factor SC-35, whereas hnRNP proteins were not affected. Correspondingly, splicing and nucleocytoplasmic transport of a coexpressed mRNA substrate was reduced by overexpression of U1-70K. The carboxy-terminal portion of U1-70K-encompassing repeats of Arg/Ser, Arg/Glu, and Arg/Asp localizes to the nucleus independently of U1 RNA and was responsible for these inhibitory effects. This region of U1-70K contains amino acid residues similar to those found in splicing factors SC-35, U2AF, su(wa), and in other SR proteins suggesting that U1-70K protein may serve as a focus of assembly for functional components of the splicing/transport machinery. These findings are compatible with models that propose that direct interaction between U1-70K and SR proteins play a regulatory role in early events of spliceosome assembly.
authors.affiliation: Department of Microbiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Romac
authors.forename: J D
authors.initials: JD
authors.lastname: Keene
mesh_terms: D001120:Arginine / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002460:Cell Line; D005786:Gene Expression Regulation; D018014:Gene Transfer Techniques; D006801:Humans; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D012333:RNA, Messenger; D011994:Recombinant Proteins; D017412:Ribonucleoprotein, U1 Small Nuclear; D001120:Arginine