title: Small nuclear ribonucleoprotein particle assembly in vivo: demonstration of a 6S RNA-free core precursor and posttranslational modification.
abstract: The in vivo synthesis and assembly of human small nuclear ribonucleoproteins (snRNPs) have been studied using pulse/chase analysis. Antibodies derived from patients with systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD) recognize distinguishable subsets of pulse-labeled snRNP peptides. These antibodies were used to immunoprecipitate sucrose gradient fractionated pulse-labeled and pulse/chased snRNP proteins. The results indicate that assembly of the U RNA-containing snRNPs is a multistep process involving prior assembly of an RNA-free 6S core particle. This precursor contains snRNP peptides D, E, F, and G, which are common to all the different U RNA-containing particles. Furthermore, a posttranslational modification of one of the U1 snRNP-specific peptides has been observed, and the kinetics of this process indicates that the modification occurs after particle assembly. Functional and structural implications of a protein core for snRNP particles are discussed.
authors.forename: D E
authors.initials: DE
authors.lastname: Fisher
authors.forename: G E
authors.initials: GE
authors.lastname: Conner
authors.forename: W H
authors.initials: WH
authors.lastname: Reeves
authors.forename: R
authors.initials: R
authors.lastname: Wisniewolski
authors.forename: G
authors.initials: G
authors.lastname: Blobel
mesh_terms: D000906:Antibodies / Q000302:isolation & purification; D000936:Antigen-Antibody Complex; D002458:Cell Fractionation; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D007951:Leukemia, Myeloid; D008180:Lupus Erythematosus, Systemic / Q000276:immunology; D008715:Methionine / Q000378:metabolism; D008957:Models, Genetic; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational; D012335:RNA, Ribosomal / Q000235:genetics*; D012342:RNA, Small Nuclear / Q000235:genetics*; D012261:Ribonucleoproteins / Q000235:genetics* / Q000302:isolation & purification; D017411:Ribonucleoproteins, Small Nuclear
chemical_list: D000906:Antibodies; D000936:Antigen-Antibody Complex; D012335:RNA, Ribosomal; D012342:RNA, Small Nuclear; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear; D008715:Methionine