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REACTIVITY SENSITIVITY MW (kDa) Isotype
H M R Endogenous 14, 16 Rabbit IgG

Western blot analysis of A172 and C2C12 cells, untreated (-) or chloroquine-treated (50 μM, overnight; +), using GABARAP (E1J4E) Rabbit mAb.

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Western blot analysis of extracts from 293T cells, mock transfected (-) or transfected with constructs expressing Myc/DDK-tagged full-length human GABARAP (hGABARAP-Myc/DDK; +), human GABARAPL1 (hGABARAPL1-Myc/DDK; +), or human GABARAPL2 (hGABARAPL2-Myc/DDK; +), using GABARAP (E1J4E) Rabbit mAb.

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Confocal immunofluorescent analysis of A172 cells, untreated (left) and chloroquine-treated (50 μM, overnight; right), using GABARAP (E1J4E) Rabbit mAb (green) and β-Actin (8H10D10) Mouse mAb #3700 (red). Blue pseudocolor = DRAQ5® #4084 (fluorescent DNA dye).

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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

Page

Immunofluorescence (Immunocytochemistry)

A. Solutions and Reagents

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

  1. 20X Phosphate Buffered Saline (PBS): (9808) To prepare 1L 1X PBS: add 50 ml 20X PBS to 950 ml dH2O, mix. Adjust pH to 8.0.
  2. Methanol, 100%
  3. Blocking Buffer (1X PBS / 5% normal serum / 0.3% Triton™ X-100): To prepare 10 ml, add 0.5 ml normal serum from the same species as the secondary antibody (e.g., Normal Goat Serum (#5425)) and 0.5 mL 20X PBS to 9.0 mL dH2O, mix well. While stirring, add 30 µl Triton™ X-100.
  4. Antibody Dilution Buffer (1X PBS / 1% BSA / 0.3% Triton X-100): To prepare 10 ml, add 30 µl Triton™ X-100 to 10 ml 1X PBS. Mix well then add 0.1 g BSA (9998), mix.
  5. Recommended Fluorochrome-conjugated Anti-Rabbit secondary antibodies:

  6. Prolong® Gold AntiFade Reagent (#9071), Prolong® Gold AntiFade Reagent with DAPI (#8961).

B. Specimen Preparation - Cultured Cell Lines (IF-IC)

NOTE: Cells should be grown, treated, fixed and stained directly in multi-well plates, chamber slides or on coverslips.

  1. Aspirate liquid, then cover cells to a depth of 2–3 mm with ice-cold 100% methanol.
  2. Allow cells to fix for 15 minutes at -20°C.
  3. Aspirate fixative, rinse three times in 1X PBS for 5 minutes each.
  4. Proceed with Immunostaining (Section C).

C. Immunostaining

NOTE: All subsequent incubations should be carried out at room temperature unless otherwise noted in a humid light-tight box or covered dish/plate to prevent drying and fluorochrome fading.

  1. Block specimen in Blocking Buffer for 60 minutes.
  2. While blocking, prepare primary antibody by diluting as indicated on datasheet in Antibody Dilution Buffer.
  3. Aspirate blocking solution, apply diluted primary antibody.
  4. Incubate overnight at 4°C.
  5. Rinse three times in 1X PBS for 5 minutes each.
  6. Incubate specimen in fluorochrome-conjugated secondary antibody diluted in Antibody Dilution Buffer for 1–2 hours at room temperature in dark.
  7. Rinse in 1X PBS as in step 5.
  8. Coverslip slides with Prolong® Gold Antifade Reagent (#9071), Prolong® Gold AntiFade Reagent with DAPI (#8961).
  9. For best results, examine specimens immediately using appropriate excitation wavelength. For long-term storage, store slides flat at 4°C protected from light.

posted December 2010

protocol id: 3

Product Usage Information

Application Dilutions
Western Blotting 1:1000
Immunofluorescence 1:400

Storage: Supplied in 10 mM sodium HEPES (pH 7.5), 150 mM NaCl, 100 µg/ml BSA, 50% glycerol and less than 0.02% sodium azide. Store at –20°C. Do not aliquot the antibody.

Specificity / Sensitivity

GABARAP (E1J4E) Rabbit mAb recognizes endogenous levels of total GABARAP protein. This antibody does not cross-react with other GABARAP family members.


Species Reactivity: Human, Mouse, Rat

Source / Purification

Monoclonal antibody is produced by immunizing animals with a synthetic peptide corresponding to residues surrounding Arg40 of human GABARAP protein.

GABAA receptor associated protein (GABARAP) is an Atg8 family protein with a key role in autophagy, which was originally discovered as a protein associated with the GABAA receptor regulating receptor trafficking to the plasma membrane (1). Proteins in this family, including microtubule-associated protein light chain 3 (LC3) and GATE-16 (GABARAPL2), become incorporated into the autophagosomal membranes following autophagic stimuli such as starvation (2). Like the other family members, GABARAP is cleaved at its carboxyl terminus, which leads to conjugation by either of the phospholipids phosphatidylethanolamine or phosphatidylserine (3,4). This processing converts GABARAP from a type I to a type II membrane bound form involved in autophagosome biogenesis. Processing of GABARAP involves cleavage by Atg4 family members (5,6) followed by conjugation by the E1 and E2 like enzymes Atg7 and Atg3 (7,8). GABARAPL1/GEC1, a protein that is highly related to GABARAP, was identified as an estrogen inducible gene, and is also associated with autophagosomes (9-11).


1.  Wang, H. et al. (1999) Nature 397, 69-72.

2.  Shpilka, T. et al. (2011) Genome Biol 12, 226.

3.  Kabeya, Y. et al. (2004) J Cell Sci 117, 2805-12.

4.  Sou, Y.S. et al. (2006) J Biol Chem 281, 3017-24.

5.  Tanida, I. et al. (2004) J Biol Chem 279, 36268-76.

6.  Hemelaar, J. et al. (2003) J Biol Chem 278, 51841-50.

7.  Tanida, I. et al. (2001) J Biol Chem 276, 1701-6.

8.  Tanida, I. et al. (2002) J Biol Chem 277, 13739-44.

9.  Chakrama, F.Z. et al. (2010) Autophagy 6, 495-505.

10.  Pellerin, I. et al. (1993) Mol Cell Endocrinol 90, R17-21.

11.  Vernier-Magnin, S. et al. (2001) Biochem Biophys Res Commun 284, 118-25.


Entrez-Gene Id 11337
Swiss-Prot Acc. O95166


For Research Use Only. Not For Use In Diagnostic Procedures.
Cell Signaling Technology® is a trademark of Cell Signaling Technology, Inc.
DRAQ5® is a registered trademark of Biostatus Limited.
Tween® is a registered trademark of ICI Americas, Inc.