Purification of mammalian histidyl-tRNA synthetase and its interaction with myositis-specific anti-Jo-1 antibodies.
Histidyl-tRNA synthetase is purified to near homogeneity from rat liver. The subunit molecular weight of histidyl-tRNA synthetase is 50,000, as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The Stokes radius and the sedimentation coefficient of histidyl-tRNA synthetase are 38 A and 6.0 S, respectively. The native molecular weight of histidyl-tRNA synthetase is calculated to be 96,000 on the basis of its hydrodynamic properties. The purified histidyl-tRNA synthetase reacts with the myositis-specific anti-Jo-1 antibodies. Anti-Jo-1 immunoglobulin G reacts with the native form of histidyl-tRNA synthetase and does not react or only weakly reacts with the denatured form. The anti-Jo-1 antibodies exhibit stronger inhibition toward histidyl-tRNA synthetase that has been preincubated with tRNA than that without preincubation. Anti-Jo-1 antibodies behave as a noncompetitive inhibitor with respect to tRNA in the aminoacylation reaction catalyzed by histidyl-tRNA synthetase. The structural features of the antigen of the anti-Jo-1 antibodies in light of these results are discussed.
D000604:Amino Acyl-tRNA Synthetases / Q000302:isolation & purification*; D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology*; D000936:Antigen-Antibody Complex; D004797:Enzyme-Linked Immunosorbent Assay; D006643:Histidine-tRNA Ligase / Q000037:antagonists & inhibitors / Q000276:immunology / Q000302:isolation & purification*; D006801:Humans; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D046911:Macromolecular Substances; D008297:Male; D008970:Molecular Weight; D009220:Myositis / Q000276:immunology*; D051381:Rats
D000888:Antibodies, Anti-Idiotypic; D000936:Antigen-Antibody Complex; D046911:Macromolecular Substances; D000604:Amino Acyl-tRNA Synthetases; D006643:Histidine-tRNA Ligase