title: Histidyl-tRNA synthetase, the myositis Jo-1 antigen, is cytoplasmic and unassociated with the cytoskeletal framework.
abstract: The myositis-specific anti-Jo-1 autoantibody, which is directed against histidyl-tRNA-synthetase, is found in 30% of polymyositis patients. The Jo-1 antigen has been reported to be a nuclear antigen by some authors. On the contrary we show that less than 2% of the total histidyl-tRNA and lysyl-tRNA synthetase activities are associated with purified rat liver nuclei or the hepatocyte intermediate filament-nuclear fraction. In the presence of polyethylene glycol, in which the high Mr multi-enzyme complex containing lysyl-tRNA synthetase is insoluble, 65% of the lysyl-tRNA synthetase and only 15% of histidyl-tRNA synthetase activities remained associated with the cytoskeletal framework. The Jo-1 antigen exhibited a diffuse granular cytoplasmic distribution in cultured rat hepatocytes as determined by indirect immunofluorescent microscopy. Hence, the Jo-1 antigen is cytoplasmic and unassociated with the cytoskeletal framework or high Mr synthetase complex in situ.
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000032:analysis*; D000818:Animals; D001323:Autoantibodies; D002467:Cell Nucleus / Q000201:enzymology; D002478:Cells, Cultured; D003593:Cytoplasm / Q000201:enzymology* / Q000276:immunology; D003599:Cytoskeleton / Q000201:enzymology* / Q000276:immunology; D005260:Female; D006643:Histidine-tRNA Ligase / Q000032:analysis* / Q000276:immunology; D008099:Liver / Q000201:enzymology / Q000276:immunology / Q000648:ultrastructure; D008250:Lysine-tRNA Ligase / Q000032:analysis; D009220:Myositis / Q000276:immunology; D051381:Rats
chemical_list: D001323:Autoantibodies; D000604:Amino Acyl-tRNA Synthetases; D006643:Histidine-tRNA Ligase; D008250:Lysine-tRNA Ligase