Biopolymers and cell. 1999; 15 (5): 409 - 414

Cytoplasmic and nuclear localization of tyrosyl-tRNA synlhetasc in higher eukaryotic cells studied by immunoelectronic microscopy

T. A. Ribkinska, Ju. l~ Ivanova, N. E. Cherny, V. I. Popcnko, G. Kh- Matsuka, A. I. Kornelyuk

The localization of tyrosyl-tRNA synthetase has been studied by immunoelectronic microscopy in bovine kidney cells and fibroblasts of RAT I line which have been treated by monoclonal antibodies T3 raised against bovine tyrosyl-tRNA synthetase an by complexes of protein A-colloidal gold. The localization of tyrosyl-tRNA syn¬thetase har been revealed both in cytoplasm and in the nucleus of mammalian cells. Tyrosyl-tRNA synthetase is located in cytoplasm mainly in the vicinity of polyribosomes what supports the compart -mentatization conception of the components of protein synthesis apparatus. A significant portion of synthetase detected in the nucleus is located mainly in the region of diffuse chromatin, and partly in the nudeolus. In general, localization of tyrosyl-tRNA synthetase in mammalian cells is very similar to the localization of p43 protein of codosome, a precursor of the EMAP II cytokine, which is highly homologous to the non-catalytic C-terminal domain of tyrosyl-tRNA synthetase. Nuclear localization of tyrosyl-tRNA synthetase implies that this enzyme is involved in some non-canonical functions in the nucleus of eukaryotic cell. It is possible that this function may be related to the export of mature tRNA from nucleus to cytoplasm.