title: Epitopes and structural domains of a RNA-binding nuclear protein, SS-B/La: similarities with adenovirus DNA-binding protein.
abstract: SS-B/La is a conserved cellular phosphoprotein of 46/48 KD molecular weight which is the target antigen of autoantibodies in sera of patients with Sjögren's syndrome. Two relatively protease-resistant domains (X and Y) were defined in the SS-B antigen from HeLa cells. Human autoantibodies to SS-B were used as reagents. Domain X is a methionine-containing, non-phosphorylated 28 KD polypeptide and is resistant to partial digestion with six different proteases. Domain Y is a 23 KD polypeptide which contains little if any methionine, but all the detectable phosphorylated amino acids. These results demonstrate that there are at least two distinct antigenic epitopes on the 46/48 KD SS-B protein, each located on a separate structural domain. The asymmetric distribution of methionine and phosphorylated amino acid residues in SS-B show striking similarity to two reported domains of the adenovirus 72 KD DNA-binding protein, which also have separate methionine and phosphorylated amino acid distributions.
mesh_terms: D017502:Adenovirus E2 Proteins; D001324:Autoantigens / Q000032:analysis* / Q000276:immunology; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D000939:Epitopes; D006367:HeLa Cells / Q000276:immunology*; D006801:Humans; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D014764:Viral Proteins / Q000032:analysis* / Q000276:immunology; D000097585:SS-B Antigen
chemical_list: D017502:Adenovirus E2 Proteins; D001324:Autoantigens; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D000939:Epitopes; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D014764:Viral Proteins; D000097585:SS-B Antigen