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REACTIVITY SENSITIVITY MW (kDa) Isotype
H R Mk Endogenous 175 Mouse IgG1
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Immunoprecipitation

Immunoprecipitation of A-431 cell lysates, untreated or EGF-treated, using Phospho-EGF Receptor (Tyr1068) (1H12) Mouse mAb (Sepharose® Bead Conjugate) and Mouse IgG (Sepharose® Bead Conjugate) #3420. The western blot was probed using Phospho-EGF Receptor (Tyr1068) (D7A5) XP® Rabbit mAb #3777.

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Immunoprecipitation for Analysis by Western Blotting

This protocol is intended for immunoprecipitation of native proteins for analysis by western immunoblot or kinase activity.

A. Solutions and Reagents

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

  1. 20X Phosphate Buffered Saline (PBS): (#9808).
  2. 10X Cell Lysis Buffer: (#9803) 20 mM Tris (pH 7.5), 150 mM NaCl, 1 mM EDTA, 1 mM EGTA, 1% Triton X-100, 2.5 mM Sodium pyrophosphate, 1 mM β-glycerophosphate, 1 mM Na3VO4, 1 μg/ml Leupeptin

    NOTE: CST recommends adding 1 mM PMSF (#8553) before use*.

  1. 3X SDS Sample Buffer: (#7722) 187.5 mM Tris-HCl (pH 6.8 at 25°C), 6% w/v SDS, 30% glycerol, 150 mM DTT, 0.03% w/v bromophenol blue
  2. 10X Kinase Buffer (for kinase assays): (#9802) To Prepare 1 ml of 1X kinase buffer, add 100 µl 10X kinase buffer to 900 µl dH2O, mix.
  3. ATP (10 mM) (for kinase assays): (#9804) To prepare 0.5 ml of ATP (200 µM), add 10 µl ATP (10 mM) to 490 µl 1X kinase buffer.

B. Preparing Cell Lysates

  1. Aspirate media. Treat cells by adding fresh media containing regulator for desired time.
  2. To harvest cells under nondenaturing conditions, remove media and rinse cells once with ice-cold PBS.
  3. Remove PBS and add 0.5 ml 1X ice-cold cell lysis buffer to each plate (10 cm) and incubate the plates on ice for 5 minutes.
  4. Scrape cells off the plates and transfer to microcentrifuge tubes. Keep on ice.
  5. Sonicate samples on ice three times for 5 seconds each.
  6. Microcentrifuge for 10 minutes at 4°C, 14,000 x g, and transfer the supernatant to a new tube. If necessary, lysate can be stored at –80°C.

C. Immunoprecipitation

  1. Take 200 μl cell lysate and add 10 μl of the immobilized antibody, incubate with rotation overnight at 4°C.
  2. Microcentrifuge for 30 seconds at 4°C. Wash pellet five times with 500 μl of 1X cell lysis buffer. Keep on ice during washes.
  3. Proceed to sample analysis by western blotting or kinase activity (section D).

D. Sample Analysis

Proceed to one of the following specific set of steps.

For Analysis by Western Immunoblotting

  1. Resuspend the pellet with 20 µl 3X SDS sample buffer. Vortex, then microcentrifuge for 30 sec at 14,000 x g.
  2. Heat the sample to 95–100°C for 2-5 min and microcentrifuge for 1 min at 14,000 x g.
  3. Load the sample (15–30 µl) on a 4–20% gel for SDS-PAGE.
  4. Analyze sample by western blot (see Western Immunoblotting Protocol).

NOTE: To minimize masking caused by denatured IgG heavy chains (~50 kDa), we recommend using Mouse Anti-Rabbit IgG (Light-Chain Specific) (L57A3) mAb (#3677) or Mouse Anti-Rabbit IgG (Conformation Specific) (L27A9) mAb (#3678) (or HRP conjugate #5127). To minimize masking caused by denatured IgG light chains (~25 kDa), we recommend using Mouse Anti-Rabbit IgG (Conformation Specific) (L27A9) mAb (#3678) (or HRP conjugate #5127).

For Analysis by Kinase Assay

  1. Wash pellet twice with 500 µl 1X kinase buffer. Keep on ice.
  2. Suspend pellet in 40 µl 1X kinase buffer supplemented with 200 µM ATP and appropriate substrate.
  3. Incubate for 30 min at 30°C.
  4. Terminate reaction with 20 µl 3X SDS sample buffer. Vortex, then microcentrifuge for 30 sec.
  5. Transfer supernatant containing phosphorylated substrate to another tube.
  6. Heat the sample to 95–100°C for 2–5 min and microcentrifuge for 1 min at 14,000 x g.
  7. Load the sample (15–30 µl) on SDS-PAGE (4–20%).

posted December 2007

protocol id: 27

Product Usage Information

Application Dilutions
Immunoprecipitation 1:20

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

Specificity / Sensitivity

Phospho-EGF Receptor (Tyr1068) (1H12) Mouse mAb (Sepharose® Bead Conjugate) detects endogenous levels of EGF receptor only when phosphorylated at Tyr1068. This antibody does not recognize EGF receptor phosphorylated at other sites, but may cross-react with other activated ErbB family members.


Species Reactivity: Human, Rat, Monkey

Source / Purification

Monoclonal antibody is produced by immunizing animals with a synthetic phosphopeptide corresponding to residues surrounding Tyr1068 of human EGF receptor.

Product Description

This Cell Signaling Technology antibody is immobilized via covalent binding of primary amino groups to N-hydroxysuccinimide (NHS)-activated Sepharose® beads. Phospho-EGF Receptor (Tyr1068) (1H12) Mouse mAb (Sepharose® Bead Conjugate) is useful for the immunoprecipitation of EGF receptor that is phosphorylated at Tyr1068. The antibody is expected to exhibit the same species cross-reactivity as the unconjugated Phospho-EGF Receptor (Tyr1068) (1H12) Mouse mAb #2236.


The epidermal growth factor (EGF) receptor is a transmembrane tyrosine kinase that belongs to the HER/ErbB protein family. Ligand binding results in receptor dimerization, autophosphorylation, activation of downstream signaling, internalization, and lysosomal degradation (1,2). Phosphorylation of EGF receptor (EGFR) at Tyr845 in the kinase domain is implicated in stabilizing the activation loop, maintaining the active state enzyme, and providing a binding surface for substrate proteins (3,4). c-Src is involved in phosphorylation of EGFR at Tyr845 (5). The SH2 domain of PLCγ binds at phospho-Tyr992, resulting in activation of PLCγ-mediated downstream signaling (6). Phosphorylation of EGFR at Tyr1045 creates a major docking site for the adaptor protein c-Cbl, leading to receptor ubiquitination and degradation following EGFR activation (7,8). The GRB2 adaptor protein binds activated EGFR at phospho-Tyr1068 (9). A pair of phosphorylated EGFR residues (Tyr1148 and Tyr1173) provide a docking site for the Shc scaffold protein, with both sites involved in MAP kinase signaling activation (2). Phosphorylation of EGFR at specific serine and threonine residues attenuates EGFR kinase activity. EGFR carboxy-terminal residues Ser1046 and Ser1047 are phosphorylated by CaM kinase II; mutation of either of these serines results in upregulated EGFR tyrosine autophosphorylation (10).


1.  Zwick, E. et al. (1999) Trends Pharmacol Sci 20, 408-12.

2.  Hackel, P.O. et al. (1999) Curr Opin Cell Biol 11, 184-9.

3.  Cooper, J.A. and Howell, B. (1993) Cell 73, 1051-4.

4.  Hubbard, S.R. et al. (1994) Nature 372, 746-54.

5.  Biscardi, J.S. et al. (1999) J Biol Chem 274, 8335-43.

6.  Emlet, D.R. et al. (1997) J Biol Chem 272, 4079-86.

7.  Levkowitz, G. et al. (1999) Mol Cell 4, 1029-40.

8.  Ettenberg, S.A. et al. (1999) Oncogene 18, 1855-66.

9.  Rojas, M. et al. (1996) J Biol Chem 271, 27456-61.

10.  Feinmesser, R.L. et al. (1999) J Biol Chem 274, 16168-73.


Entrez-Gene Id 1956
Swiss-Prot Acc. P00533


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