Revision 3

#4640Store at -20C

Cell Signaling Technology

Orders: 877-616-CELL (2355) [email protected]

Support: 877-678-TECH (8324)

Web: [email protected] cellsignal.com

3 Trask LaneDanversMassachusetts01923USA
For Research Use Only. Not for Use in Diagnostic Procedures.
Applications:

WB

REACTIVITY:

H M R Mk

SENSITIVITY:

Endogenous

MW (kDa):

100

SOURCE:

Rabbit

UniProt ID:

#Q8IVT5

Entrez-Gene Id:

8844

Product Information

Product Usage Information

Application Dilution
Western Blotting 1:1000

Storage

Supplied in 10 mM sodium HEPES (pH 7.5), 150 mM NaCl, 100 µg/ml BSA and 50% glycerol. Store at –20°C. Do not aliquot the antibody.

Specificity / Sensitivity

KSR1 Antibody detects endogenous levels of total KSR1 protein.

Species Reactivity:

Human, Mouse, Rat, Monkey

Source / Purification

Polyclonal antibodies are produced by immunizing animals with a synthetic peptide corresponding to residues near the carboxy terminus of human KSR1 protein. Antibodies are purified by protein A and peptide affinity chromatography.

Background

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).

  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.

Species Reactivity

Species reactivity is determined by testing in at least one approved application (e.g., western blot).

Western Blot Buffer

IMPORTANT: For western blots, incubate membrane with diluted primary antibody in 5% w/v BSA, 1X TBS, 0.1% Tween® 20 at 4°C with gentle shaking, overnight.

Applications Key

WB: Western Blotting

Cross-Reactivity Key

H: human M: mouse R: rat Hm: hamster Mk: monkey Vir: virus Mi: mink C: chicken Dm: D. melanogaster X: Xenopus Z: zebrafish B: bovine Dg: dog Pg: pig Sc: S. cerevisiae Ce: C. elegans Hr: horse GP: Guinea Pig Rab: rabbit All: all species expected

Trademarks and Patents

Cell Signaling Technology is a trademark of Cell Signaling Technology, Inc.
All other trademarks are the property of their respective owners. Visit cellsignal.com/trademarks for more information.

Limited Uses

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Revision 3
#4640

KSR1 Antibody

Western Blotting Image 1: KSR1 Antibody Expand Image
Western blot analysis of extracts from various cells lines using KSR1 Antibody.