title: Anti-threonyl-tRNA synthetase, a second myositis-related autoantibody.
abstract: An autoantibody known as PL-7 was found in the serum of four patients with myositis and one with a systemic lupus erythematosus-like syndrome. The PL-7 antigen is an 80,000 dalton polypeptide that coprecipitates with transfer RNA. In aminoacylation reactions, PL-7 IgG inhibited the charging of tRNA with threonine but had little or no effect on charging with other amino acids. Experimental antibodies raised against purified threonyl-tRNA synthetase recognized the same 80,000 dalton polypeptide, but tRNA was not coprecipitated. We conclude that PL-7 antibody is directed at threonyl-tRNA synthetase, and that different antigenic sites are recognized by the human and experimental autoantibodies. Our findings emphasize the link between myositis and autoimmunity to tRNA-related structures.
mesh_terms: D000328:Adult; D000604:Amino Acyl-tRNA Synthetases / Q000276:immunology*; D000818:Animals; D000918:Antibody Specificity; D001323:Autoantibodies / Q000032:analysis* / Q000502:physiology; D001324:Autoantigens / Q000032:analysis; D001667:Binding, Competitive; D000939:Epitopes; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009220:Myositis / Q000276:immunology*; D011233:Precipitin Tests; D012313:RNA / Q000032:analysis; D011817:Rabbits; D013914:Threonine-tRNA Ligase / Q000276:immunology* / Q000302:isolation & purification
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D000939:Epitopes; D012313:RNA; D000604:Amino Acyl-tRNA Synthetases; D013914:Threonine-tRNA Ligase