title: Assembly and localization of the U1-specific snRNP C protein in the amphibian oocyte.
abstract: To study the intranuclear localization of the U1-specific snRNP C protein and its assembly into U1 snRNPs, we injected transcripts encoding a myc-tagged C protein into amphibian oocytes. The distribution of protein translated from the injected RNA was essentially the same in continuous and pulse-label experiments. In both cases the C protein localized within the germinal vesicle in those structures known to contain U1 snRNPs, namely the lampbrush chromosome loops and hundreds of extrachromosomal granules called snurposomes. Oocytes were also injected with an antisense oligodeoxynucleotide that caused truncation of U1 snRNA at the 5' end. In these oocytes, myc-tagged C protein localized normally in the germinal vesicle and could be immunoprecipitated together with truncated U1 snRNA. These experiments suggest that the C protein can enter the germinal vesicle on its own and there associate with previously assembled U1 snRNPs. In transfected tissue culture cells, the myc-tagged C protein localized within the nucleus in a speckled pattern similar to that of endogenous U1 snRNPs.
authors.affiliation: Department of Embryology, Carnegie Institution, Baltimore, Maryland 21210.
authors.forename: M F
authors.initials: MF
authors.lastname: Jantsch
authors.forename: J G
authors.initials: JG
authors.lastname: Gall
mesh_terms: D000595:Amino Acid Sequence; D000663:Amphibians / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport / Q000187:drug effects; D002451:Cell Compartmentation; D002467:Cell Nucleus / Q000737:chemistry; D003513:Cycloheximide / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D016259:Genes, myc / Q000235:genetics; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D012342:RNA, Small Nuclear / Q000378:metabolism*; D011993:Recombinant Fusion Proteins; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D012455:Salamandridae / Q000378:metabolism; D014018:Tissue Distribution; D014981:Xenopus / Q000235:genetics
chemical_list: D012333:RNA, Messenger; D012342:RNA, Small Nuclear; D011993:Recombinant Fusion Proteins; D017412:Ribonucleoprotein, U1 Small Nuclear; D003513:Cycloheximide