Technical Data
PA28, gamma, Mid (Proteasome Activator 28-gamma subunit)
Proteasome activator 28 (PA28), also known as 11S regulator, is composed of two homologous subunits, alpha (a) and beta (b), that share ~ 50% amino acid identity.1 A separate but related protein, PA28gamma, was originally identified as Ki antigen from sera of patients with systemic lupus erythematosus.1-3 PA28a and PA28b are located primarily in the cytoplasm, whereas PA28g is located in the nucleus.4,5 PA28 binds to the outer rings on both ends of the 20S proteasome to form a football-like structure.6,7 Binding of PA28 greatly stimulates multiple peptidase activities of the 20S proteasome in an ATP-independent reaction, but lacks the ability to degrade large protein substrates, suggesting that PA28 may cooperate with the 26 S proteasome in a sequential proteolytic pathway.8,9 In addition to its nuclear localization, PA28g differs from PA28a and PA28b in that it is not responsive to stimulation with IFN-g.10 Experiments with mice lacking the PA28g gene (Psme3) demonstrate that PA28g may be involved in cell cycle control; although PA28g is not essential for development, its absence causes retardation of cell proliferation and body growth.10 Abnormally high expression of PA28g has been observed in thyroid cancer, particularly in regions of cancer cells where growth rate is accelerated.11 PA28g interacts directly with Hepatitis C virus (HCV) core protein, which becomes retained in the cells nucleus,12 and with MEKK3, which phosphorylates PA28g and increases its cellular levels.13

Suitable for use in Western Blot and Immunoprecipitation. Other applications not tested.

Recommended Dilution:
Western Blot: 1-3ug/ml
Immunoprecipitation: 7ug/reaction
Optimal dilutions to be determined by the researcher.

Positive Controls:
Human MeWo malignant melanoma, A375 malignant melanoma, Jurkat T-lymphocyte leukemia, HeLa cervical carcinoma, and HL-60 acute myeloid leukemia cell lysates.

Storage and Stability:
May be stored at 4C for short-term only. For long-term storage, store at -20C. Aliquots are stable for at least 12 months at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
PabIgGAffinity Purified
100ug4C (-20C Glycerol)Blue IceHumanRabbit
Synthetic peptide derived from an internal region of the human, mouse, rat and pig PA28g (proteosome activator 28g, Ki antigen) protein.
Purified by immunoaffinity chromatography.
Supplied as a liquid in PBS, pH 7.4, 0.09% sodium azide, before the addition of glycerol to 40%.
Recognizes the PA28g human protein at ~30kD. No reactivity has been observed with purified recombinant PA28a or PA28b proteins. Species sequence homology: mouse, rat and pig-100%.
Intended for research use only. Not for use in human, therapeutic, or diagnostic applications.
1. Ahn JY, et al. FEBS Lett 366:37-42,1995.
2. Nikaido T, et al. Clin Exp Immunol 79:209-214,1990.
3. Tanahashi N, et al. Genes Cells 2:195-211,1997.
4. Soza A, et al. FEBS Lett 413:27-34,1997.
5. Wojcik C, et al. Eur J Cell Biol 77:151-160,1998.
6. Baumeister W, et al. Cell 92:367-380,1998.
7. Gray CW, et al. J Mol Biol 236:7-15,1994.
8. Groll M, et al. Nature 386:463-471,1997.
9. Ma CP, et al. J Biol Chem 267:10515-10523,1992.
10. Murata S, et al. J Biol Chem 274(53):38211-38215,1999.
11. Okamura T, et al. J Clin Endocrinol Metab 88:1374-1383,2003.
12. Moriishi K, et al. J Virol 77:10237-10249,2003.
13. Hagemann C, et al. Biochem J 373:71-79,2003.