A mammalian tRNAHis-Containing antigen is recognized by the polymyosits-specific antibody antijo-1

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Abstract
The mammalian cell antigen reactive with the autoantibody anti-jo-1 has been shown to contain tRNARis. The RNA sequence of this human and mouse cell tRNA was determined in a search for unusual features that might be realted to antigenicity. The 5' terminal nuleotide is unique among other sequenced tRNAs in that it is a methylated guanine. The presence of the hypermodified base quenine, which occurs in the wobble postition of the anticodon of tRNAHis from several species, was not detected in the tRNAHis immunoprecipitated by anti-jo-1 from either human HeLa or mouse Friend erytholeukeia cell extracts. The binding of protien(s) appears to confer antigenicity on tRNAHis since either protienase K treatment or phenol extraction resulted in the loss of immunoprecipatability. However, we have not suceeded in identifying an antigenic protien, and we find that the antigenic complex is not resolved from purified tRNAHis by Sepharcryl S-200 column chromatography. Immunofluorescence studies indicate that the antigenic from of tRNAHis is located preferentially in the mammalian cell cytoplasm. The results presented here are discussed in light of an earlier report (1) on the nature of the jo-1 antigen.