title: Autoantibodies to the U2 small nuclear ribonucleoprotein in a patient with scleroderma-polymyositis overlap syndrome.
abstract: Autoantibodies directed against the U2 small nuclear ribonucleoprotein (snRNP) have been found in the serum of a patient with scleroderma-polymyositis overlap syndrome. This specificity, called anti-(U2)-RNP, is distinct from all previously described autoantibodies, including those that precipitate related snRNPs: anti-Sm antibodies, which react with the entire set of U1, U2, U4, U5, and U6 snRNPs, and anti-(U1)RNP antibodies, which recognize only U1 snRNPs. From HeLa cell extracts, anti-(U2)RNP immunoprecipitates predominantly one 32P-labeled RNA species, identified as U2 small nuclear RNA, and six [35S]methionine-labeled protein bands, A' (Mr = 32,000), B (Mr = 28,000), D (Mr = 16,000), E (Mr = 13,000), F (Mr = 12,000), and G (Mr = 11,000). Protein blot analysis reveals that the A' protein carries (U2)RNP antigenic determinant(s) and therefore represents a polypeptide unique to the U2 snRNP; the B protein associated with U2 snRNPs may also be unique. Like U1 and the other Sm snRNPs, U2 snRNPs occupy a nuclear, non-nucleolar location and are antigenically conserved from insects to man. An antibody specific for the U2 snRNP will be useful in deciphering the function of this particle.
mesh_terms: D001323:Autoantibodies / Q000032:analysis*; D005260:Female; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells / Q000276:immunology; D006801:Humans; D005779:Immunodiffusion; D009220:Myositis / Q000150:complications; D012261:Ribonucleoproteins / Q000276:immunology*; D017411:Ribonucleoproteins, Small Nuclear; D012595:Scleroderma, Systemic / Q000150:complications / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear