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Native - Calf Thymus
Vial Size
Histidyl tRNA synthetase
Histidine tRNA ligase
Uniprot ID:  Q2KI84
mRNA RefSeq:  NM_001046066
Protein RefSeq:  NP_001039531
Polymyositosis (PM) and dermatomyositis (DM) are idiopathic inflammatory myopathies. The existence of autoantibodies to nuclear and cytoplasmic antigens, in particular to the aminoacyl-tRNA synthetase group of enzymes, in the sera of up to 89% of patients indicates that these diseases have an autoimmune origin. The most common autoantibody in PM and DM is anti Jo-1, occurring in 15-20% of all myositis patients and about 30% of adult PM patients.

Jo-1 autoantibodies are capable of inhibiting the activity of the target antigen (HRS) and can immunoprecipitate labelled enzyme as well as its specific tRNA. HRS has a molecular weight of 55 kDa in SDS-polyacrylamide electrophoresis, and is believed to exist as a dimer in its native state.

The amino acid sequence of human Jo-1 antigen has been determined by cloning and sequencing its cDNA. It contains three structural motifs typical of class IIa aminoacyl transferases and two signature regions common to histidyl-tRNA synthetases. The human enzyme amino acid sequence shows significant homology to those of the enzymes from yeast (47.5%) and E. coli. It is predicted to have a coiled-coil α-helical structure that is characteristic of many autoantigens and which contains the major autoantigenic epitope. 

PDF-logo-dl Jo-1 datasheet
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  • Rosa, M.D. et al. (1983) Nucl. Acids Res. 11, 853
  • Biswas, T. et al. (1987) J. Immunol. Meth. 98, 235
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  • Walker, E.J. et al. (1987) J. Immunol. Meth. 96, 149

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