Antigen/Purification: Collapse
The antigen is a phosphopeptide corresponding to amino acid residues surrounding the phospho-Thr449 of Arabidopsis S6K1.
The antibody is prepared from pooled rabbit serum by affinity purification via sequential chromatography on phospho- and dephospho-peptide affinity columns.
Biological Significance: Collapse
Ribosomal s6 kinase is a member of a family of protein kinases involved in signal transduction. The subfamily S6K has two known homologues: S6K1 and S6K2. First characterized in mammals, S6K1 is controlled by target-of-rapamycin (TOR) kinase, which plays a central regulatory role in growth signaling pathways (Dufner and Thomas 1999). Osmotic stress inhibition of S6K is mediated by the TOR kinase pathway (Mahfouz et al., 2006). The activation of mammalian S6K1 involves phosphorylation at thr389 (Pearson et al., 2005), however its orthologue in Arabidopsis suggests that plant S6K1 thr449 is its functional equivalent (Schepetilnikov et al., 2011). The phytohormone auxin triggers TOR activation, which is followed by S6K1 phosphorylation at thr449, which in turn is critical for translation reinitiation (Schepetilnikov et al., 2013). Rapamycin effectively inactivates S6K1 thr449 phosphorylation in Arabidopsis seedlings, which suppresses TOR PK activity and ultimately plant growth (Xiong Y and Sheen J, 2011).
Storage
100 µl in 10 mM HEPES (pH 7.5), 150 mM NaCl, 100 µg BSA per ml and 50% glycerol. Adequate amount of material to conduct 10-mini Western Blots.
For long term storage –20° C is recommended. Stable at –20° C for at least 1 year.
General References
Dufner A, Thomas G (1999) Ribosomal S6 kinase signalin g and the control of translation. Exp Cell Res 253(1):100-9.
Mahfouz MM, Kim S, Delauney AJ, Verma DP (2006) Arabidopsis TARGET OF RAPAMYCIN interacts with RAPTOR, which regulates the activity of S6 Kinase in response to osmotic stress signals. The Plant Cell 18:477-490.
Pearson RB, Dennis PB, Han JW, Williamson NA, Kozma SC, Wettenhall RE, Thomas G (1995) The principal target of rapamycin-induced p70s6k inactivation is a novel phosphorylation site within a conserved hydrophobic domain. EMBO J. 14(21):5 279-87.
Schepetilnikov M, Kobayashi K, Geldreich A, Caranta C, Robaglia C, Keller M, Ryabova L (2011) Viral factor TAV recruits TOR/S6K1 signalling to activate reinitiation after long ORF translation. EMBO J. 30:1343-13556.
Schepetilnikov M, Dimitrova M, Mancera-Martinez E, Geldreich A, Keller M, Ryabova L (2013) TOR and S6K1 promote translation reinitiation of uORF-containing mRNAs via phosphorylation of eIF3h. EMBO J, 32:1087-1102.
Xiong Y, Sheen J (2012) Rapamycin and glucose-Target of Rapamycin (TOR) protein signaling in plants. J Biol Chem 287(4):2836-2842.
