Abstract: Objective To investigate the role of Ro52 antigen fragment from amino acid (AA) 119 to 264 that contains leucine zipper motif in forming the epitopes of Ro52 autoantigen. Methods cDNA encoding Ro52 antigen fragment from aa 119 to 264 was amplified by PCR from human heart cDNA first strand. The obtained cDNA fragment was inserted into vector pMTY4 and transformed into E. coli pop2136 for fusion protein expression. The recombinant fusion protein was then purified, and the antigenicity was determined by immunoblotting. Results A 28 000 Dalton fusion protein was obtained. It was highly expressed in host E. coli pop2136. 61.90% of the anti-full-length Ro52 positive sera reacted with the fusion protein in immunoblotting. Conclusion The results suggest that the antigen fragment from the 119 AA to 264 AA that contains the leucine zipper motif represents an important epitope region in Ro52 autoantigen.

Key words: Epitopes, DNA, recombinant, Ro52 autoantigen