A motif in human histidyl-tRNA synthetase which is shared among several aminoacyl-tRNA synthetases is a coiled-coil that is essential for enzymatic activity and contains the major autoantigenic epitope.

摘要: In myositis, disease-specific autoantibodies may be directed against an aminoacyl-tRNA synthetase, usually histidyl-tRNA synthetase. To explore the basis for this phenomenon, we have made recombinant synthetase in baculovirus system. It was enzymatically active and recognized by human autoantibodies. A truncated protein lacking first 60 amino acids inactive as antigen enzyme. This region is within two exons, predicted to a coiled-coil configuration, found some other synthetases but not Escherichia coli or yeast Circular dichroism showed that peptides from (amino 1-60 1-47) high alpha-helical content, smaller fragments (1-30, 14-45, 31-60) do not. The with content could inhibit almost completely, whereas were unable so. acid sequence of domain resembles extended arm near NH2 terminus bacterial seryl-tRNA well similar regions eukaryotic synthetases, raising possibility serves tRNA-stabilizing role has been preserved common ancestor.