ABSTRACT
Objective:Rheumatoid arthritis(RA) is a systemic autoimmune disease,but its etiology is unclear.Therefore,it is urgent to search antigens which is relate to induce this disease,however,there are few reports about the new self-antigens at home and abroad.In this study,we investigate new autoantigen through cloning.Methods: We used antigens in synovium of patients with rheumatoid arthritis as probe,extracted mRNA from synoviocyte,performed cDNA library immunological screening and sequence,and analyzed the conformation and performed Northern blotting.Results: We found that new autoantigen had 36.5% homology with retinoblastoma binding protein 1(RBP1)and it was found that these special protein structure such as AT-rich interaction domain,chromo domain,A+T-hook and TAF homology domain.Therefore,it will be named RBP1-like Protein(Rbik).Rbik RNA is not only expressed in the synovial membrane,but also in the heart,small intestine,muscle and other organs.Conclusion: We report that the discovery of the new autoantibodies to RBP1-like Protein(Rbik)may provide a new possible index and target in diagnosis and therapy.