Mapping of the immunoreactive domains of a small nuclear ribonucleoprotein-associated Sm-D autoantigen.
The Sm-D(D1) small nuclear ribonucleoprotein (snRNP) polypeptide is a major target of autoantibodies diagnostic for systemic lupus erythematosus. The cDNA encoding the protein from Raji cells was expressed in Escherichia coli as a fusion protein with anthranilate synthase (TrpE-Sm-D). When tested by protein blot, the recombinant polypeptide was strongly immunoreactive under defined blotting conditions, which appear to facilitate the refolding of the polypeptide into a native conformation. Multiple translational fusions between the trpE gene and fragments encompassing the length of the Sm-D coding sequence were constructed for epitope mapping. The results describe two general patterns of anti-Sm reactivity: (i) antibodies that recognize only the full-length antigen and are presumably directed against discontinuous epitopes, and (ii) antibodies that recognize the carboxy terminus of the antigen which embodies an extended/charged structure.
D000595:Amino Acid Sequence; D001324:Autoantigens / Q000276:immunology*; D015153:Blotting, Western; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D000939:Epitopes; D006801:Humans; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D011993:Recombinant Fusion Proteins / Q000276:immunology; D015183:Restriction Mapping; D017411:Ribonucleoproteins, Small Nuclear / Q000235:genetics / Q000276:immunology*; D055517:snRNP Core Proteins
D001324:Autoantigens; D000939:Epitopes; D011993:Recombinant Fusion Proteins; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins; D004247:DNA