Recombinant Human PA28 Activator beta Subunit Protein, CF

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Product Details

Recombinant Human PA28 Activator beta Subunit Protein, CF Summary

Product Specifications

>95%, by SDS-PAGE under reducing conditions and visualized by Colloidal Coomassie® Blue stain
Recombinant Human His6-PA28 Activator beta Subunit is ideal for the activation of latent 20S Proteasome complexes. Reaction conditions will need to be optimized for each specific application. Initially, we recommend a 5-15-fold molar excess of Recombinant Human His6-PA28 Activator beta Subunit relative to 20S Proteasome.
E. coli-derived human PA28 Activator beta Subunit protein
Contains an N-terminal 6-His tag.
Accession #
Predicted Molecular Mass
29 kDa

Product Datasheets

Carrier Free

What does CF mean?

CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our recombinant proteins. Adding a carrier protein enhances protein stability, increases shelf-life, and allows the recombinant protein to be stored at a more dilute concentration. The carrier free version does not contain BSA.

What formulation is right for me?

In general, we advise purchasing the recombinant protein with BSA for use in cell or tissue culture, or as an ELISA standard. In contrast, the carrier free protein is recommended for applications, in which the presence of BSA could interfere.


Formulation X mg/ml (X µM) in 50 mM HEPES pH 8.0, 200 mM NaCl, 1mM DTT
Shipping The product is shipped with dry ice or equivalent. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage: Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
  • 12 months from date of receipt, -70 °C as supplied.
  • 3 months, -70 °C under sterile conditions after opening.
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Background: PA28 Activator beta Subunit

The Proteasome Activator 28 (PA28) Regulatory Complex, also known as the 11S Regulatory (REG) Complex, is a ring-shaped, multimeric, ATP-independent regulatory complex that can bind to one or both ends of the 20S Proteasome or 20S Immunoproteasome (1,2). The PA28 Regulatory Complex stimulates the proteasome to hydrolyze small peptides, but not ubiquitinated proteins, for the production of peptides for MHC class I antigen presentation (3-7). Three PA28 Regulatory Complex subunits, alpha, beta, and gamma, have been identified and can oligomerize to form the PA28 Regulatory Complex (8-10). While the expression of the PA28 alpha and beta subunits are induced by IFN-gamma, the PA28 gamma subunit is not significantly affected (11,12).

The human PA28 Activator beta Subunit, also known as 11S REG beta, is a 239 amino acid (aa) member of the PA28 family of regulatory proteins with a predicted molecular weight of 27 kDa. The mouse and rat PA28 beta orthologs share 93% and 92% aa sequence identity with the human protein, respectively. In vivo, PA28 beta forms hetero-heptamers or -hexamers with PA28 alpha (13-15). PA28 beta cannot form active homo-oligomers in vitro and cannot activate the 20S Proteasome in the absence of PA28 alpha (8). In addition to regulating production of MHC class I antigens, the PA28 alpha/beta regulatory complex may also protect against oxidative stress (16). This protein has been purified from E. Coli.

  1. Cascio, P. et al. (2002) EMBO J. 21:2636.
  2. Shibatani, T. et al. (2006) Mol. Biol. Cell 17:4962.
  3. Ma, C.P. et al. (1992) J. Biol. Chem. 267:10515.
  4. Wilk, S. et al. (2000) Arch. Biochem. Biophys. 383:265.
  5. Knowlton, J.R. et al. (1997) Nature 390:639.
  6. Groettrup, M. et al. (1996) Nature 381:166.
  7. Dick, T.P. et al. (1996) Cell 86:253.
  8. Kuehn, L. & B. Dahlmann (1997) Mol. Biol. Rep. 24:89.
  9. Li, J. & M. Rechsteiner (2001) Biochimie 83:373.
  10. Realini, C. et al. (1997) J. Biol. Chem. 272:25483.
  11. Jiang, H. & J.J. Monaco (1997) Immunogenetics 46:93.
  12. Ahn, J.Y. et al. (1995) FEBS Lett. 366:37.
  13. Zhang, Z. et al. (1999) Biochemistry 38:5651.
  14. Song, X. et al. (1996) J. Biol. Chem. 271:26410.
  15. Mott, J.D. et al. (1994) J. Biol. Chem. 269:31466.
  16. Li, J. et al. (2011) FASEB J. 25:883.
Long Name
Proteasome (Prosome, Macropain) Activator Subunit 2
Entrez Gene IDs
5721 (Human); 19188 (Mouse); 29614 (Rat)
Alternate Names
11S regulator complex beta subunit; 11S regulator complex subunit beta; Activator of multicatalytic protease subunit 2; MCP Activator; MCP activator, 31-kD subunit; PA28 Activator beta Subunit; PA28b; PA28betacell migration-inducing protein 22; proteasome (prosome, macropain) activator subunit 2 (PA28 beta); Proteasome activator 28 subunit beta; proteasome activator 28-beta; proteasome activator complex subunit 2; proteasome activator hPA28 subunit beta; PSME2; REGbeta; REG-beta


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