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Phospho-p70 S6 Kinase (Thr421/Ser424) Antibody #9204

Applications	Reactivity	Sensitivity	MW (kDa)	Source
W IP	H M R Mk	Endogenous	70, 85	Rabbit

Applications Key:  W=Western Blotting  IP=Immunoprecipitation
Reactivity Key:  H=Human  M=Mouse  R=Rat  Mk=Monkey
Species cross-reactivity is determined by western blot. Species enclosed in parentheses are predicted to react based on 100% sequence homology.

Protocols

9204:

Immunoprecipitation, Western Blotting

Specificity / Sensitivity

Phospho-p70 S6 Kinase (Thr421/Ser424) Antibody detects endogenous levels of p70 S6 kinase only when phosphorylated at Thr421/Ser424. This antibody also detects p85 S6 kinase when phosphorylated at the corresponding sites (Thr444/Ser447).

Source / Purification

Polyclonal antibodies are produced by immunizing animals with a synthetic phosphopeptide corresponding to residues surrounding Thr421/Ser424 of human p70 S6 kinase. Antibodies are purified by protein A and peptide affinity chromatography.

Background

p70 S6 kinase is a mitogen activated Ser/Thr protein kinase that is required for cell growth and G1 cell cycle progression (1,2). p70 S6 kinase phosphorylates the S6 protein of the 40S ribosomal subunit and is involved in translational control of 5' oligopyrimidine tract mRNAs (1). A second isoform, p85 S6 kinase, is derived from the same gene and is identical to p70 S6 kinase except for 23 extra residues at the amino terminus, which encode a nuclear localizing signal (1). Both isoforms lie on a mitogen activated signaling pathway downstream of phosphoinositide-3 kinase (PI-3K) and the target of rapamycin, FRAP/mTOR, a pathway distinct from the Ras/MAP kinase cascade (1). The activity of p70 S6 kinase is controlled by multiple phosphorylation events located within the catalytic, linker and pseudosubstrate domains (1). Phosphorylation of Thr229 in the catalytic domain and Thr389 in the linker domain are most critical for kinase function (1). Phosphorylation of Thr389, however, most closely correlates with p70 kinase activity in vivo (3). Prior phosphorylation of Thr389 is required for the action of phosphoinositide 3-dependent protein kinase 1 (PDK1) on Thr229 (4,5). Phosphorylation of this site is stimulated by growth factors such as insulin, EGF and FGF, as well as by serum and some G-protein-coupled receptor ligands, and is blocked by wortmannin, LY294002 (PI-3K inhibitor) and rapamycin (FRAP/mTOR inhibitor) (1,6,7). Ser411, Thr421 and Ser424 lie within a Ser-Pro-rich region located in the pseudosubstrate region (1). Phosphorylation at these sites is thought to activate p70 S6 kinase via relief of pseudosubstrate suppression (1,2). Another LY294002 and rapamycin sensitive phosphorylation site, Ser371, is an in vitro substrate for mTOR and correlates well with the activity of a partially rapamycin resistant mutant p70 S6 kinase (8).

1. Pullen, N. and Thomas, G. (1997) FEBS Lett. 410, 78-82.
2. Dufner, A. and Thomas, G. (1999) Exp. Cell Res. 253, 100-109.
3. Weng, Q.P. et al. (1998) J. Biol. Chem. 273, 16621-16629.
4. Pullen, N. et al. (1998) Science 279, 707-710.
5. Alessi, D.R. et al. (1998) Curr. Biol. 8, 69-81.
6. Polakiewicz, R.D. et al. (1998) J. Biol. Chem. 273, 23534-23541.
7. Fingar, D.C. et al. (2002) Genes Dev. 16, 1472-1487.
8. Saitoh, M. et al. (2002) J. Biol. Chem. 277, 20104-20112.

Application References

• Duan, C. et al. (1999) Insulin-like growth factor (IGF)-I regulates IGF-binding protein-5 gene expression through the phosphatidylinositol 3-kinase, protein kinase B/Akt, and p70 S6 C138 kinase signaling pathway. J. Biol. Chem. 274, 37147-37153. Applications: Western Blot
• Haider, U. G. et al. (2003) Resveratrol increases serine15-phosphorylated but transcriptionally impaired p53 and induces a reversible DNA replication block in serum-activated vascular smooth muscle cells. Mol. Pharm. 63, 925-932. Applications: Western Blotting
• Valentinis, B. et al. (2000) Insulin receptor substrate-1, p70S6K, and cell size in transformation and differentiation of hemopoietic cells. J. Biol. Chem. 275, 25451-25459. Applications: Western Blot
• Hara, K. et al. (1998) Amino acid sufficiency and mTOR regulate p70 S6 kinase and eIF-4E BP1 through a common effector mechanism. J. Biol. Chem. 273, 14484-14494. Applications: Western Blot
• Sellers, L. A. et al. (2000) Receptor isoforms mediate opposing proliferative effects through gbetagamma-activated p38 or Akt pathways. Mol. Cell. Biol. 20, 5974-5985. Applications: Western Blot
• Khaleghpour, K. et al. (1999) Translational homeostasis: eukaryotic translation initiation factor 4E control of 4E-binding protein 1 and p70 S6 kinase activities. Mol. Cell. Biol. 19, 4302-4310. Applications: Western Blot

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Companion Products

• 2708 p70 S6 Kinase (49D7) Rabbit mAb
• 9430 PhosphoPlus® p70 S6 Kinase (Thr389, Thr421/Ser424) Antibody Kit
• 9203 p70 S6 Kinase Control Cell Extracts
• 9206 Phospho-p70 S6 Kinase (Thr389) (1A5) Mouse mAb
• 9202 p70 S6 Kinase Antibody
• 9205 Phospho-p70 S6 Kinase (Thr389) Antibody
• 4858 Phospho-S6 Ribosomal Protein (Ser235/236) (D57.2.2E) XP^® Rabbit mAb
• 9234 Phospho-p70 S6 Kinase (Thr389) (108D2) Rabbit mAb
• 7074 Anti-rabbit IgG, HRP-linked Antibody
• 7720 Prestained Protein Marker, Broad Range (Premixed Format)
• 7727 Biotinylated Protein Ladder Detection Pack
• 7003 20X LumiGLO^® Reagent and 20X Peroxide

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This product is intended for research purposes only. The product is not intended to be used for therapeutic or diagnostic purposes in humans or animals.