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REACTIVITY SENSITIVITY MW (kDa) SOURCE
H Transfected Only 155 Rabbit

Western Blotting

Western blot analysis of extracts from COS cells, untransfected (lane 1), or transfected with wild-type ASK1 (lanes 2,3), using Phospho-ASK1 (Thr845) Antibody (upper) or ASK1 Antibody #3762 (lower). In lane 3, the lysate was treated with lamda phosphatase to demonstrate phospho-specificity of Phospho-ASK1 (Thr845) Antibody.

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Western Blotting

Western blot analysis of extracts from HEK293 cells, untransfected (lane 1) or transfected with wild-type ASK1 (lane 2) or T845A mutant ASK1 (lane 3), using Phospho-ASK1 (Thr845) Antibody (upper) or ASK1 Antibody #3762 (lower). (Lysates were provided by Dr. Wang Min, Dept. of Pathology, Yale University, New Haven, CT).

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Western Blotting Protocol

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.

NOTE: Please refer to primary antibody datasheet or product webpage for recommended antibody dilution.

A. Solutions and Reagents

NOTE: Prepare solutions with reverse osmosis deionized (RODI) or equivalent grade water.

  1. 20X Phosphate Buffered Saline (PBS): (#9808) To prepare 1 L 1X PBS: add 50 ml 20X PBS to 950 ml dH2O, mix.
  2. 10X Tris Buffered Saline (TBS): (#12498) To prepare 1 L 1X TBS: add 100 ml 10X to 900 ml dH2O, mix.
  3. 1X SDS Sample Buffer: Blue Loading Pack (#7722) or Red Loading Pack (#7723) Prepare fresh 3X reducing loading buffer by adding 1/10 volume 30X DTT to 1 volume of 3X SDS loading buffer. Dilute to 1X with dH2O.
  4. 10X Tris-Glycine SDS Running Buffer: (#4050) To prepare 1 L 1X running buffer: add 100 ml 10X running buffer to 900 ml dH2O, mix.
  5. 10X Tris-Glycine Transfer Buffer: (#12539) To prepare 1 L 1X Transfer Buffer: add 100 ml 10X Transfer Buffer to 200 ml methanol + 700 ml dH2O, mix.
  6. 10X Tris Buffered Saline with Tween® 20 (TBST): (#9997) To prepare 1 L 1X TBST: add 100 ml 10X TBST to 900 ml dH2O, mix.
  7. Nonfat Dry Milk: (#9999).
  8. Blocking Buffer: 1X TBST with 5% w/v nonfat dry milk; for 150 ml, add 7.5 g nonfat dry milk to 150 ml 1X TBST and mix well.
  9. Wash Buffer: (#9997) 1X TBST.
  10. Bovine Serum Albumin (BSA): (#9998).
  11. Primary Antibody Dilution Buffer: 1X TBST with 5% BSA; for 20 ml, add 1.0 g BSA to 20 ml 1X TBST and mix well.
  12. Biotinylated Protein Ladder Detection Pack: (#7727).
  13. Prestained Protein Marker, Broad Range (Premixed Format): (#7720).
  14. Blotting Membrane and Paper: (#12369) This protocol has been optimized for nitrocellulose membranes. Pore size 0.2 µm is generally recommended.
  15. Secondary Antibody Conjugated to HRP: Anti-rabbit IgG, HRP-linked Antibody (#7074).
  16. Detection Reagent: SignalFire™ ECL Reagent (#6883).

B. Protein Blotting

A general protocol for sample preparation.

  1. Treat cells by adding fresh media containing regulator for desired time.
  2. Aspirate media from cultures; wash cells with 1X PBS; aspirate.
  3. Lyse cells by adding 1X SDS sample buffer (100 µl per well of 6-well plate or 500 µl for a 10 cm diameter plate). Immediately scrape the cells off the plate and transfer the extract to a microcentrifuge tube. Keep on ice.
  4. Sonicate for 10–15 sec to complete cell lysis and shear DNA (to reduce sample viscosity).
  5. Heat a 20 µl sample to 95–100°C for 5 min; cool on ice.
  6. Microcentrifuge for 5 min.
  7. Load 20 µl onto SDS-PAGE gel (10 cm x 10 cm).

    NOTE: Loading of prestained molecular weight markers (#7720, 10 µl/lane) to verify electrotransfer and biotinylated protein ladder (#7727, 10 µl/lane) to determine molecular weights are recommended.

  8. Electrotransfer to nitrocellulose membrane (#12369).

C. Membrane Blocking and Antibody Incubations

NOTE: Volumes are for 10 cm x 10 cm (100 cm2) of membrane; for different sized membranes, adjust volumes accordingly.

I. Membrane Blocking

  1. (Optional) After transfer, wash nitrocellulose membrane with 25 ml TBS for 5 min at room temperature.
  2. Incubate membrane in 25 ml of blocking buffer for 1 hr at room temperature.
  3. Wash three times for 5 min each with 15 ml of TBST.

II. Primary Antibody Incubation

  1. Incubate membrane and primary antibody (at the appropriate dilution and diluent as recommended in the product datasheet) in 10 ml primary antibody dilution buffer with gentle agitation overnight at 4°C.
  2. Wash three times for 5 min each with 15 ml of TBST.
  3. Incubate membrane with Anti-rabbit IgG, HRP-linked Antibody (#7074 at 1:2000) and anti-biotin, HRP-linked Antibody (#7075 at 1:1000–1:3000) to detect biotinylated protein markers in 10 ml of blocking buffer with gentle agitation for 1 hr at room temperature.
  4. Wash three times for 5 min each with 15 ml of TBST.
  5. Proceed with detection (Section D).

D. Detection of Proteins

Directions for Use:

  1. Wash membrane-bound HRP (antibody conjugate) three times for 5 minutes in TBST.
  2. Prepare 1X SignalFire™ ECL Reagent (#6883) by diluting one part 2X Reagent A and one part 2X Reagent B (e.g. for 10 ml, add 5 ml Reagent A and 5 ml Reagent B). Mix well.
  3. Incubate substrate with membrane for 1 minute, remove excess solution (membrane remains wet), wrap in plastic and expose to X-ray film.

* Avoid repeated exposure to skin.

posted June 2005

revised November 2013

protocol id: 10

Western Blot Reprobing Protocol

Reprobing of an existing membrane is a convenient means to immunoblot for multiple proteins independently when only a limited amount of sample is available. It should be noted that for the best possible results a fresh blot is always recommended. Reprobing can be a valuable method but with each reprobing of a blot there is potential for increased background signal. Additionally, it is recommended that you verify the removal of the first antibody complex prior to reprobing so that signal attributed to binding of the new antibody is not leftover signal from the first immunoblotting experiment. This can be done by re-exposing the blot to ECL reagents and making sure there is no signal prior to adding the next primary antibody.

A. Solutions and Reagents

NOTE: Prepare solutions with reverse osmosis deionized (RODI) or equivalently purified water.

  1. Wash Buffer: Tris Buffered Saline with Tween® 20 (TBST-10X) (#9997)
  2. Stripping Buffer: To prepare 100 ml, mix 0.76 g Tris base, 2 g SDS and 700 μl β-mercaptoethanol. Bring to 100 ml with deionized H2O. Adjust pH to 6.8 with HCl.

B. Protocol

  1. After film exposure, wash membrane four times for 5 min each in TBST. Best results are obtained if the membrane is not allowed to dry.
  2. Incubate membrane for 30 min at 50°C in stripping buffer (with slight agitation).
  3. Wash membrane six times for 5 min each in TBST.
  4. (Optional) To assure that the original signal is removed, wash membrane twice for 5 min each with 10 ml of TBST. Incubate membrane with LumiGLO® with gentle agitation for 1 min at room temperature. Drain membrane of excess developing solution. Do not let dry. Wrap in plastic wrap and expose to x-ray film.
  5. Wash membrane again four times for 5 min each in TBST.
  6. The membrane is now ready to reuse. Start detection at the "Membrane Blocking and Antibody Incubations" step in the Western Immunoblotting Protocol.

posted June 2005

Product Usage Information

Application Dilutions
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

Phospho-ASK1 (Thr845) Antibody detects transfected ASK1 only when phosphorylated at threonine 845.


Species Reactivity: Human
Species predicted to react based on 100% sequence homology: Mouse

Source / Purification

Polyclonal antibodies are produced by immunizing animals with a synthetic phosphopeptide corresponding to residues surrounding Thr845 of mouse ASK1. Antibodies are purified by protein A and peptide affinity chromatography.

Apoptosis signal-regulating kinase 1 (ASK1), a MAP kinase kinase kinase, plays essential roles in stress-induced apoptosis (1,2). ASK1 is activated in response to a variety of stress-related stimuli through distinct mechanisms and activates MKK4 and MKK3, which in turn activate JNK and p38 (3). Overexpression of ASK1 activates JNK and p38 and induces apoptosis in several cell types through signals involving the mitochondrial cell death pathway. Embryonic fibroblasts or primary neurons derived from ASK1-/- mice are resistant to stress-induced JNK and p38 activation as well as cell death (4,5). Phosphorylation at Ser967 is essential for ASK1 association with 14-3-3 proteins and suppression of cell death (6). Oxidative stress induces dephosphorylation of Ser967 and phosphorylation of Thr845 in the activation loop of ASK1, both of which are correlated with ASK1 activity and ASK1-dependent apoptosis (7,8). Akt phosphorylates ASK1 at Ser83, which attenuates ASK1 activity and promotes cell survival (9).


1.  Ichijo, H. et al. (1997) Science 275, 90-94.

2.  Wang, X.S. et al. (1996) J. Biol. Chem. 271, 31607-31611.

3.  Matsuzawa, A. and Ichijo, H. (2001) J. Biochem. (Tokyo) 130, 1-8.

4.  Tobiume, K. et al. (2001) EMBO Rep. 2, 222-228.

5.  Nishitoh, H. et al. (2002) Genes Dev. 16, 1345-1355.

6.  Zhang, L. et al. (1999) Proc. Natl. Acad. Sci. USA 96, 8511-8515.

7.  Tobiume, K. et al. (2002) J. Cell. Physiol. 191, 95-104.

8.  Goldman, E.H. et al. (2004) J. Biol. Chem. in press, .

9.  Kim, A.H. et al. (2001) Mol. Cell. Biol. 21, 893-901.


Entrez-Gene Id 4217
Swiss-Prot Acc. Q99683


For Research Use Only. Not For Use In Diagnostic Procedures.
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