Generation of polyclonal antibodies specifi c to the ribosomal protein S6 kinase isoform-p85S6K1 and directed to the N-terminal (1-23 aa) extension of p85S6K1. Methods. Animal immunization with synthetic (1-23 aa) peptide, ELISA, western blot, immunoprecipitation, immunofl uorescent analysis. Results. Polyclonal antibodies have been generated, which specifi cally recognize only p85 but not p70 isoform of S6K1 in western blot, immunoprecipitation and immunofl uorescence analysis. Conclusions. The obtained antibodies can be recommended for studies on the p85S6K1 and other S6K1 isoforms possessing the N-terminal extension-the identifi cation of binding protein partners, analysis of subcellular localization under different physiological conditions, elucidation of the signal transduction pathways involving different S6K1 isoforms. K e y w o r d s: Ribosomal protein S6 kinase 1 (S6K1), S6K1 isoforms, p70 S6K1, p85 S6K1, polyclonal antibodies.

Tyrosyl-tRNA synthetase (TyrRS) is one of the key enzymes of protein biosynthesis. In addition to its basic role, this enzyme reveals some important non-canonical functions. Under apoptotic conditions, the full-length enzyme splits into two fragments having distinct cytokine activities, thereby linking protein synthesis to cytokine signaling pathways. The NH 2 -terminal catalytic fragment, known as miniTyrRS, binds strongly to the CXCchemokine receptor CXCR1 and, like interleukin 8, functions as a chemoattractant for polymorphonuclear leukocytes. On the other hand, an extra COOH-terminal domain of human TyrRS has cytokine activities like those of a mature human endothelial monocyte-activating polypeptide II (EMAP II). Moreover, the etiology of specific diseases (cancer, neuronal pathologies, autoimmune disorders, and disrupted metabolic conditions) is connected to specific aminoacyl-tRNA synthetases. Here we report the generation and characterization of monoclonal antibodies specific to N-and C-terminal domains of TyrRS. Recombinant TyrRS and its N-and C-terminal domains were expressed as His-tag fusion proteins in bacteria. Affinity purified proteins have been used as antigens for immunization and hybridoma cell screening. Monoclonal antibodies specific to catalytic N-terminal module and C-terminal EMAP II-like domain of TyrRS may be useful as tools in various aspects of TyrRS function and cellular localization.