title: Immunolocalization of 7-2-ribonucleoprotein in the granular component of the nucleolus.
abstract: Certain autoimmune sera contain antibodies against a nucleolar ribonucleoprotein particle associated with 7-2-RNA (R. Reddy et al. (1983) J. Biol. Chem. 258, 1383; C. Hashimoto and J. A. Steitz (1983) J. Biol. Chem. 258, 1379). In this study, we showed by immunofluorescence microscopy that antibodies reactive with 7-2-ribonucleoprotein immunolocalized in the granular regions of actinomycin D and 5,6-dichloro-1-beta-D-ribofurano-sylbenzimidazole (DRB)--segregated nucleoli from Vero cells. By electron microscopic immunocytochemistry, antigen-antibody complexes were located in the granular component of transcriptionally active nucleoli from rat liver hepatocytes and HeLa cells. Anti-7-2-RNP antibodies from two autoimmune sera immunoprecipitated a major protein of Mr 40,000 from [35S] methionine--labeled HeLa cell extract. The immunolocalization data suggest that 7-2-ribonucleoprotein may be involved in stages of ribosome biogenesis which take place in the granular component of the nucleolus, i.e., assembly, maturation, and/or transport of preribosomes.
authors.affiliation: Department of Dermatology, University of Erlangen-Nürnberg, Federal Republic of Germany.
authors.forename: G
authors.initials: G
authors.lastname: Reimer
authors.forename: I
authors.initials: I
authors.lastname: Raska
authors.forename: U
authors.initials: U
authors.lastname: Scheer
authors.forename: E M
authors.initials: EM
authors.lastname: Tan
mesh_terms: D000818:Animals; D001323:Autoantibodies / Q000276:immunology*; D001324:Autoantigens / Q000502:physiology*; D002460:Cell Line; D002466:Cell Nucleolus / Q000648:ultrastructure*; D011232:Chemical Precipitation; D005455:Fluorescent Antibody Technique; D006801:Humans; D007163:Immunosorbent Techniques; D008854:Microscopy, Electron; D008970:Molecular Weight; D012342:RNA, Small Nuclear / Q000502:physiology*; D012261:Ribonucleoproteins / Q000378:metabolism*; D012270:Ribosomes / Q000502:physiology
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D012342:RNA, Small Nuclear; D012261:Ribonucleoproteins