Isolation and characterization of a cDNA clone encoding the 60-kD component of the human SS-A/Ro ribonucleoprotein autoantigen.
SS-A/Ro is a nucleocytoplasmic ribonucleoprotein (RNP) particle that is a common target of autoimmune response in Sjögren's syndrome (SS) and systemic lupus erythematosus (SLE). Previously, SS-A/Ro has been shown to be composed of at least two polypeptide antigens of 60 and 52 kD noncovalently associated with a set of small RNAs, designated Y1-Y5. A serum from an SS patient was selected to screen a lambda gt11 cDNA library constructed from human T cell lymphoblastic leukemia (MOLT-4) mRNA. An immunoreactive clone was isolated that possessed a 1.8-kb cDNA insert. In vitro transcription and translation of the cDNA resulted in the synthesis of a 57.5-kD polypeptide which was specifically immunoprecipitated by SS-A/Ro antisera. The identity of the cDNA encoded protein as the 60-kD SS-A/Ro antigen was established by proteolytic peptide mapping of the cDNA-encoded protein and the 60-kD HeLa cell antigen. The sequence of the cDNA shows that the 60-kD SS-A/Ro protein possesses both RNA binding protein consensus sequences and a single zinc-finger motif. Recombinant SS-A/Ro antigen produced in bacteria proved to be a sensitive and specific reagent for detection of anti-SS-A/Ro antibodies in patient sera. The availability of the 60-kD SS-A/Ro cDNA will enable detailed analysis of the molecular structure and function of the SS-A/Ro RNP particle and its role in autoimmune pathology.
Ben-Chetrit
E
E
W.M. Keck Autoimmune Disease Center, Scripps Clinic, La Jolla, California 92037.
Gandy
B J
BJ
Tan
E M
EM
Sullivan
K F
KF
D000595:Amino Acid Sequence; D000974:Antibodies, Antinuclear; D001324:Autoantigens / Q000235:genetics* / Q000276:immunology; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000302:isolation & purification*; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D007106:Immune Sera; D008969:Molecular Sequence Data; D008970:Molecular Weight; D014176:Protein Biosynthesis; D020733:RNA, Small Cytoplasmic; D011993:Recombinant Fusion Proteins / Q000138:chemical synthesis / Q000302:isolation & purification; D012261:Ribonucleoproteins / Q000276:immunology / Q000302:isolation & purification*; D014158:Transcription, Genetic; D000099207:SS-A Antigen
D000974:Antibodies, Antinuclear; D001324:Autoantigens; D004247:DNA; D007106:Immune Sera; D020733:RNA, Small Cytoplasmic; D011993:Recombinant Fusion Proteins; D012261:Ribonucleoproteins; D000099207:SS-A Antigen; C116006:RO60 protein, human