A repeated proline-rich sequence in Sm B/B' and N is a dominant epitope recognized by human and murine autoantibodies.
Reactivity of a murine monoclonal anti-Sm B antibody was localized to a cDNA clone T3/2 encompassing codons 177-221 of Sm N and to a series of 10-residue synthetic peptides containing a proline-rich motif. Human sera containing anti-B antibodies also bound to this proline-rich motif in the form of a heptamer, PPGMRPP, and could distinguish the N/B sequence from similar sequences present in the RNP A and C polypeptides in a number of cases. Monoclonal antibodies binding to either this peptide or to a determinant present on both B and D polypeptides inhibited the majority of anti-B binding in 50% of anti-B sera. The region of N/B containing PPGMRPP also bears a second epitope, sterically blocked by monoclonal antibody KSm 5. This hotspot binds 40-60% of anti-B activity in 30% of anti-B sera. These data suggest that the anti-Sm B epitope recognition repertoire is restricted in SLE patients.
Williams
D G
DG
Clinical Immunology Division, Kennedy Institute of Rheumatology, London, UK.
Sharpe
N G
NG
Wallace
G
G
Latchman
D S
DS
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000918:Antibody Specificity; D001323:Autoantibodies / Q000276:immunology*; D001324:Autoantigens / Q000276:immunology*; D001327:Autoimmune Diseases / Q000276:immunology; D000939:Epitopes; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis / Q000276:immunology; D010455:Peptides / Q000276:immunology; D055232:Proline-Rich Protein Domains; D011994:Recombinant Proteins / Q000276:immunology; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins
D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D001324:Autoantigens; D000939:Epitopes; D009842:Oligopeptides; D010455:Peptides; D011994:Recombinant Proteins; D017411:Ribonucleoproteins, Small Nuclear; C526417:SNRPN protein, human; C526416:Snrpb protein, mouse; D055517:snRNP Core Proteins