Biopolymers and cell. 2006; 22 (1): 82 - 84

Regulation of S6K1 subcellular localization by Casein kinase 2

G. G. Panasyuk, I. O. Nemazanyy, A. M. Zhyvoloup, V. V. Filonenko, I. T. Gout

Casein Kinase 2 (CK2) is physiological binding partner of ribosomal protein S6 kinase 1 identified using of two-hybrid yeast system. The specificity of interaction between b-subunit of CK2 and S6K1 was confirmed in vitro, also it was shown that Ser17 of S6K1 can be phosphorylated by CK2. The presented data suggest that Ser17 phosphorylation is the important event of S6K1 export from the nucleus. Immunoprecipitation studies of S6K1 and CK2 from cytoplasmic fraction of NIH3T3 cells indicate the formation of protein complex S6K1/CK2 in the nucleus, but not in the cytoplasm. Further fluorescent microscopy studies demonstrated that phosphorylation mimicking mutant of S6K1 (S17E) is not accumulated in the nucleus through the activated export of kinase from the nucleus.

Key words: S6K1, S6K2, CK2b, nuclear export.