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REACTIVITY SENSITIVITY MW (kDa) Isotype
H M R Mk Endogenous 150 Rabbit IgG
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Immunoprecipitation of HeLa cell lysates using Rabbit (DA1E) mAb IgG XP® Isotype Control (Sepharose® Bead Conjugate) #3423 (lane 1) or Raptor (24C12) Rabbit mAb (Sepharose® Bead Conjugate) (lane 2). The western blot was probed using Raptor (24C12) Rabbit mAb #2280.

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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

Raptor (24C12) Rabbit mAb (Sepharose® Bead Conjugate) detects endogenous levels of total Raptor protein.


Species Reactivity: Human, Mouse, Rat, Monkey

Source / Purification

Raptor (24C12) Rabbit mAb is produced by immunizing animals with a synthetic peptide corresponding to the sequence of human Raptor.

Product Description

This Cell Signaling Technology antibody is immobilized via covalent binding of primary amino groups to N-hydroxysuccinimide (NHS)-activated Sepharose® beads. Raptor (24C12) Rabbit mAb (Sepharose® Bead Conjugate) is useful for immunoprecipitation assays. The antibody is expected to exhibit the same species cross-reactivity as the unconjugated Raptor (24C12) Rabbit mAb #2280.


The regulatory associated protein of mTOR (Raptor) was identified as an mTOR binding partner that mediates mTOR signaling to downstream targets (1,2). Raptor binds to mTOR substrates, including 4E-BP1 and p70 S6 kinase, through their TOR signaling (TOS) motifs and is required for mTOR-mediated phosphorylation of these substrates (3,4). Binding of the FKBP12-rapamycin complex to mTOR inhibits the mTOR-raptor interaction, suggesting a mechanism for rapamycin's specific inhibition of mTOR signaling (5). This mTOR-raptor interaction and its regulation by nutrients and/or rapamycin is dependent on a protein called GβL (6). GβL is also part of the rapamycin-insensitive complex between mTOR and rictor (rapamycin-insensitive companion of mTOR), and may mediate rictor-mTOR signaling to downstream targets including PKCα (7). Furthermore, the rictor-mTOR complex has been identified as the previously elusive PDK2 responsible for the phosphorylation of Akt/PKB on Ser473, facilitating phosphorylation of Akt/PKB on Thr308 by PDK1 and required for the full activation of Akt/PKB (8).

Recently raptor has been identified as a direct substrate of the AMP-activated protein kinase (AMPK) (9). AMPK phosphorylates raptor on Ser722/Ser792 (9). This phosphorylation is essential for inhibition of the raptor-containing mTOR complex 1 (mTORC1) and induces cell cycle arrest when cells are stressed for energy (9). These findings suggest that raptor is a critical switch that correlates cell cycle progression with energy status.


1.  Sarbassov, D.D. et al. (2004) Curr Biol 14, 1296-302.

2.  Sarbassov, D.D. et al. (2005) Science 307, 1098-101.

3.  Hara, K. et al. (2002) Cell 110, 177-189.

4.  Kim, D.H. et al. (2002) Cell 110, 163-175.

5.  Beugnet, A. et al. (2003) J. Biol. Chem. 278, 40717-40722.

6.  Nojima, H. et al. (2003) J. Biol. Chem. 278, 15461-15464.

7.  Oshiro, N. et al. (2004) Genes Cells 9, 359-366.

8.  Kim, D.H. et al. (2003) Mol. Cell 11, 895-904.

9.  Gwinn, D.M. et al. (2008) Mol Cell 30, 214-26.


Entrez-Gene Id 57521
Swiss-Prot Acc. Q8N122


For Research Use Only. Not For Use In Diagnostic Procedures.
Cell Signaling Technology® is a trademark of Cell Signaling Technology, Inc.
U.S. Patent No. 5,675,063.