Technical Data
KSR (Kinase Suppressor of Ras, KSR1, BKSR1, dKsr, EK31, hb, Positive Ras Signaling Mediator Family Member, RSU2, Suppressor of Activated let 60 Ras SUR3, Suppressor of Ras1 31, SR31)
KSR1 (kinase supressor of Ras) was identified from a genetic screen in Drosophila and C. elegans as a component of the Ras signaling pathway (1). KSR1 has a putative carboxy-terminal kinase domain that lacks a key Lys residue for phospho-group transfer. Although reports indicate that ceramide and EGF activate KSR1 (2,3), other evidence demonstrates that KSR1 regulates Raf in a kinase- independent manner (4,5). It is now widely accepted that KSR1 functions as a scaffold that binds MEK1/2 and 14-3-3 protein constitutively and binds ERK1/2 in a Ras activation- dependent manner (1,5,6). HSP70/HSP90 and p50 Cdc37 associate with the KSR1 complex to ensure its stability (5). Multiple phosphorylation sites have been identified: Ser297 and Ser392 mediate 14-3-3 binding, and putative MAPK phosphorylation sites include Thr260, Thr274 and Ser443 (6). C-TAK1 (Cdc25C-associated kinase 1) binds and phosphorylates KSR1 at Ser392 in quiescent cells (7). In response to stimuli, Ser392 is dephosphorylated by PP2A, which leads to ERK1/2 association and allows the KSR1 complex to translocate from cytosol to membrane, where the MAPK pathway is activated (8). IMP, a Ras-responsive E3 ubiquitin ligase, is also involved in interaction with KSR1 and may regulate its localization and stability (9). Very high expression levels of KSR1 inhibit MAPK signaling, whereas physiological levels promote MAPK signaling, indicating that the scaffold protein can turn signaling on or off depending on the scaffold concentration (10).

Suitable for use in Western Blot. Other applications not tested.

Recommended Dilution:
Western Blot: 1:1000. Incubate membrane with diluted antibody in 5% w/v BSA, 1X TBS, 0.1%
Tween-20 at 4C with gentle shaking, overnight.
Optimal dilutions to be determined by the researcher.

Storage and Stability:
May be stored at 4C for short-term only. For long-term storage, aliquot and store at -20C. Aliquots are stable for at least 12 months at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
PabIgGAffinity Purified
100ul-20CBlue IceHumanRabbit
Not determined
Synthetic peptide derived from a region surrounding Gly910 of human KSR1 (KLH-coupled).
Purified by Protein A affinity chromatography.
Supplied in 10mM sodium HEPES pH 7.5, 150mM NaCl, 100ug/ml BSA and 50% glycerol.
Recognizes human KSR1. Species crossreactivity: mouse, rat, monkey.
Intended for research use only. Not for use in human, therapeutic, or diagnostic applications.
1. Morrison, D.K. (2001) J. Cell Sci. 114, 1609-1612, 2. Zhang, Y. et al. (1997) Cell 89, 63-72, 3. Xing, H.R. and Kolesnick, R. (2001) J. Biol. Chem. 276, 9733-9741, 4. Michaud, N. R. et al. (1997) Proc. Natl. Acad. Sci. USA 94, 12792-12796, 5. Stewart, S. et al. (1999) Mol. Cell. Biol. 19, 5523-5534, 6. Muller, J. et al. (2001) Mol. Cell 8, 983-993, 7. Cacace, A. M. et al. (1999) Mol. Cell. Biol. 19, 229-240, 8. Ory, S. et al. (2003) Curr. Biol. 13, 1356-1364, 9. Matheny, S. A. et al. (2004) Nature 427, 256-260, 10. Kortum, R.L. and Lewis, R.E. (2004) Mol Cell Biol 24, 4407-16.