Molecular characterization of human Ro/SS-A antigen. Amino terminal sequence of the protein moiety of human Ro/SS-A antigen and immunological activity of a corresponding synthetic peptide.
The Ro/SS-A antigen was purified from an Epstein-Barr virus-transformed human B lymphoblastoid cell line. The amino terminal amino acid sequence of the 60-kD polypeptide bearing this antigenic epitope was determined to be: (formula; see text) A peptide composed of residue 6-19 was synthesized by the solid-phase method. Immunodiffusion-defined monospecific autoimmune sera to Ro/SS-A reacted with this synthetic peptide in ELISA, whereas autoantibodies with other specificities such as anti-La/SS-B and anti-Sm, as well as normal human sera, were not reactive. In addition, rabbit anti-peptide 6-19 antisera reacted specifically with native human Ro/SS-A antigen in ELISA. Furthermore, this synthetic peptide inhibited the binding of rabbit anti-peptide antiserum to native human Ro/SS-A. An additional synthetic peptide corresponding to residues 7-24 partially inhibited the binding of a patient anti-Ro/SS-A serum to native Ro/SS-A. These results suggest that the amino terminal portion of the molecule represents a major epitope of Ro/SS-A. The determination of the amino acid sequence of Ro/SS-A and the availability of synthetic peptide(s) bearing this antigen should provide additional approaches to further characterize the autoimmune response to this antigen.
Lieu
T S
TS
Department of Dermatology, University of Texas Health Science Center, Dallas 75235.
Newkirk
M M
MM
Capra
J D
JD
Sontheimer
R D
RD
D000595:Amino Acid Sequence; D000818:Animals; D000937:Antigen-Antibody Reactions; D001324:Autoantigens / Q000276:immunology / Q000302:isolation & purification*; D001402:B-Lymphocytes / Q000276:immunology; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000276:immunology*; D020733:RNA, Small Cytoplasmic; D011817:Rabbits; D012261:Ribonucleoproteins; D013056:Spectrophotometry, Ultraviolet; D000099207:SS-A Antigen
D001324:Autoantigens; D007106:Immune Sera; D010455:Peptides; D020733:RNA, Small Cytoplasmic; D012261:Ribonucleoproteins; D000099207:SS-A Antigen; C116006:RO60 protein, human