title: A mammalian tryptophanyl-tRNA synthetase is associated with protein kinase activity.
abstract: Bovine Trp-tRNA synthetase is a dimer with subunit molecular mass of 60 kDa (p60) which catalyzes ATP-dependent formation of tryptophanyl-tRNA. Evidence is presented that Trp-tRNA synthetase whose homogeneity had been proven by SDS/PAGE and silver staining of the gel is autophosphorylated in vitro. Anti-(Trp-tRNA synthetase) antibodies, whose specificity was verified by using a combination of different approaches, were able to effectively inhibit and immunoprecipitate the Trp-tRNA-synthetase-associated kinase activity. The two-dimensional tryptic phosphopeptide map of autophosphorylated p60 Trp-tRNA synthetase was found to be similar to that of its major 40-kDa degradation fragment bearing resemblance to previously demonstrated unlabeled peptide patterns of the Trp-tRNA synthetase forms. Trp-tRNA synthetase which had undergone denaturation during SDS/PAGE, regained serine/threonine specific protein kinase activity (PK 60) after guanidine treatment. Trp-tRNA synthetase induced phosphorylation of specific substrate such as 100-kDa protein in non-immune but not in anti-(Trp-tRNA synthetase) sera which distinguishes Trp-tRNA-synthetase-associated kinase from other protein kinases. Sequence analysis permitted the identification of regions of bovine Trp-tRNA synthetase sharing similarity with the catalytic domains of known protein kinases. These findings suggest that PK 60 and Trp-tRNA synthetase (p60) are either closely related or identical.
authors.affiliation: Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Israel.
authors.forename: E L
authors.initials: EL
authors.lastname: Paley
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000918:Antibody Specificity; D002417:Cattle; D017124:Conserved Sequence; D019281:Dimerization; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010449:Peptide Mapping; D010766:Phosphorylation; D011233:Precipitin Tests; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014369:Tryptophan-tRNA Ligase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D011494:Protein Kinases; D014369:Tryptophan-tRNA Ligase