Two human tRNA(Ala) families are recognized by autoantibodies in polymyositis sera

Autoantibodies to aminoacyl-tRNA synthetases are common in myositis. Sera of one particular class, the PL-12 specificity, contain separate antibodies reacting with alanyl-tRNA synthetase and tRNA(Ala). We show here that the anti-RNA antibodies recognize at least six distinguishable human tRNA(Ala) species, grouped in two sequence families. We have elucidated the complete nucleotide sequence of two tRNA(Ala) species from HeLa cells that are closely related to silkworm moth tRNA(Ala), as well as the partial sequence of a third species. All three contain the anticodon IGC. No tRNAs with pyrimidine in the "wobble" position were found in the immunoprecipitate, and such species may fail to interact with the antibody.