Upstream / Downstream

Explore pathways related to this product.

Antibody Guarantee

CST Antibody Performance Guarantee

LEARN MORE  

Questions?

Find answers on our FAQs page.

ANSWERS  

Visit PhosphoSitePlus®

PTM information and tools available.

LEARN MORE

REACTIVITY SENSITIVITY MW (kDa) Isotype
H M R Endogenous 23, 28 Rabbit IgG

Western blot analysis of extracts from various cell lines using PSMB8/LMP7 (D1K7X) Rabbit mAb (upper) and GAPDH (D16H11) XP® Rabbit mAb #5174 (lower). (The T2 cell line contains a homozygous deletion of PSMB8/LMP7 (13)).

Learn more about how we get our images

Western blot analysis of extracts from HeLa and SW620 cells, untreated (-) or treated with Human Interferon-γ (hIFN-γ) #8901 (100 ng/ml, 72 hr; +), using PSMB8/LMP7 (D1K7X) Rabbit mAb (upper) and GAPDH (D16H11) XP® Rabbit mAb #5174 (lower).

Learn more about how we get our images

Western blot analysis of extracts from 293T cells, mock transfected (-) or transfected with constructs expressing Myc/DDK-tagged full-length human PSMB5 (hPSMB5-Myc/DDK; +) or Myc/DDK-tagged full-length human PSMB8 (hPSMB8-Myc/DDK; +), using PSMB8/LMP7 (D1K7X) Rabbit mAb (upper) and DYKDDDDK Tag Antibody #2368 (lower).

Learn more about how we get our images
Image
Image
Image
Image
Image
Image
Page

Western Blotting Protocol

For western blots, incubate membrane with diluted primary antibody in 5% w/v nonfat dry milk, 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. Primary Antibody Dilution Buffer: 1X TBST with 5% nonfat dry milk; for 20 ml, add 1.0 g nonfat dry milk to 20 ml 1X TBST and mix well.
  11. Biotinylated Protein Ladder Detection Pack: (#7727).
  12. Prestained Protein Marker, Broad Range (Premixed Format): (#7720).
  13. Blotting Membrane and Paper: (#12369) This protocol has been optimized for nitrocellulose membranes. Pore size 0.2 µm is generally recommended.
  14. Secondary Antibody Conjugated to HRP: Anti-rabbit IgG, HRP-linked Antibody (#7074).
  15. 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: 263

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, 50% glycerol and less than 0.02% sodium azide. Store at –20°C. Do not aliquot the antibody.

Specificity / Sensitivity

PSMB8/LMP7 (D1K7X) Rabbit mAb recognizes endogenous levels of total PSMB8/LMP7 protein. This antibody recognizes both 28 kDa precursor and 23 kDa mature forms of PSMB8/LMP7 and does not cross-react with PSMB5 protein. This antibody recognizes proteins of unknown origin in the 80-100 kDa range.


Species Reactivity: Human, Mouse, Rat

Source / Purification

Monoclonal antibody is produced by immunizing animals with a synthetic peptide corresponding to residues near the carboxy terminus of human PSMB8/LMP7 protein.

The 26S proteasome is a highly abundant proteolytic complex involved in the degradation of ubiquitinated substrate proteins. It consists largely of two sub-complexes, the 20S catalytic core particle (CP) and the 19S/PA700 regulatory particle (RP) that can cap either end of the CP. The CP consists of two stacked heteroheptameric β-rings (β1-7) that contain three catalytic β-subunits and are flanked on either side by two heteroheptameric α-rings (α1-7). The RP includes a base and a lid, each having multiple subunits. The base, in part, is composed of a heterohexameric ring of ATPase subunits belonging to the AAA (ATPases Associated with diverse cellular Activities) family. The ATPase subunits function to unfold the substrate and open the gate formed by the α-subunits, thus exposing the unfolded substrate to the catalytic β-subunits. The lid consists of ubiquitin receptors and DUBs that function in recruitment of ubiquitinated substrates and modification of ubiquitin chain topology (1,2). Other modulators of proteasome activity, such as PA28/11S REG, can also bind to the end of the 20S CP and activate it (1,2).


Constitutively expressed core particle subunits PSMB5, PSMB7, and PSMB6 provide chymotrypsin-like, trypsin-like, and caspase-like activities, respectively (3). In immune cells involved in antigen presentation, these subunits are replaced by highly homologous, induced β-subunits to form the immunoproteasome (4,5).

Proteasome subunit beta type-8 (PSMB8, LMP7) is expressed as a proenzyme that is cleaved to form the mature PSMB8 (LMP7) immunoproteasome core particle subunit (6). Interferon-γ induces expression of PSMB8, which functionally replaces the PSMB5 core particle subunit in immunoproteasome processing of MHC class I-restricted peptide antigens (7). Research studies suggest that reduced PSMB8 expression or expression of the non-functional LMP7-E1 isoform may impair immunoproteasome assembly, and that PSMB8 deficiency results in reduced MHC class I molecule expression (8-10). Inhibition of PSMB8 in murine rheumatoid arthritis models attenuates disease indicators, suggesting that PSMB8 is a potential therapeutic target in the treatment of some proinflammatory autoimmune diseases (11). Mutations in the corresponding PSMB8 gene can cause an autoinflammatory syndrome known as CANDLE Syndrome (12).


1.  Finley, D. (2009) Annu Rev Biochem 78, 477-513.

2.  Lee, M.J. et al. (2011) Mol Cell Proteomics 10, R110.003871.

3.  Murata, S. et al. (2009) Nat Rev Mol Cell Biol 10, 104-15.

4.  Boes, B. et al. (1994) J Exp Med 179, 901-9.

5.  Cardozo, C. and Kohanski, R.A. (1998) J Biol Chem 273, 16764-70.

6.  Groettrup, M. et al. (2010) Nat Rev Immunol 10, 73-8.

7.  Akiyama, K. et al. (1994) FEBS Lett 343, 85-8.

8.  Heink, S. et al. (2006) Cancer Res 66, 649-52.

9.  De, M. et al. (2003) J Biol Chem 278, 6153-9.

10.  Fehling, H.J. et al. (1994) Science 265, 1234-7.

11.  Muchamuel, T. et al. (2009) Nat Med 15, 781-7.

12.  Liu, Y. et al. (2012) Arthritis Rheum 64, 895-907.

13.  Salter, R.D. et al. (1985) Immunogenetics 21, 235-46.


Entrez-Gene Id 5696
Swiss-Prot Acc. P28062


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