• Purity

  >95%, by SDS-PAGE under reducing conditions and visualized by silver stain

• Endotoxin Level

  <0.01 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured by its ability to inhibit the IL-2-dependent proliferation of MO7e human megakaryocytic leukemic cells. Avanzi, G.     et al. (1988) Br. J. Haematol.     69:359. The ED    ₅₀ for this effect is 0.35-1.4 µg/mL in the presence of 30 ng/mL of recombinant human IL-2.

• Source

  Chinese Hamster Ovary cell line, CHO-derived

  Rat CD25/IL-2 R alpha (Glu22-Gln235) Accession # P26897	IEGRMDP	Mouse IgG2a (Glu98-Lys330)
  N-terminus		C-terminus

• Accession #

• N-terminal Sequence    
  Analysis

  Glu22

• Structure / Form

  Disulfide-linked homodimer

• Predicted Molecular Mass

  51.6 kDa (monomer)

• SDS-PAGE

  70-85 kDa, reducing conditions

Background: CD25/IL-2 R alpha

IL-2 receptor alpha (IL-2 R alpha ), also known as CD25, is a 55 kDa type I membrane glycoprotein that belongs to the family of cytokine receptors that utilize the common gamma chain subunit ( gamma _c). IL-2 R alpha is primarily expressed on activated T cells and on regulatory T cells (Treg) (1-3). The rat IL-2 R alpha cDNA encodes a 267 amino acid (aa) precursor that includes a 21 aa signal peptide, a 214 aa extracellular domain (ECD) with two Sushi domains, a 21 aa transmembrane segment, and an 11 aa cytoplasmic domain (4). Within the ECD, rat IL-2 R alpha shares 58% and 81% aa sequence identity with human and mouse IL-2 R alpha, respectively. It shares approximately 15% aa sequence identity with IL-4, -7, -9, -15, and -21 receptor subunits that also complex with gamma _c. IL-2 R beta (CD122) and gamma _c (IL-2 R gamma /CD132) dimerize to form a constitutively expressed intermediate affinity IL-2 receptor (5, 6). By itself, IL-2 R alpha binds IL-2 with low affinity. It associates with IL-2 R beta and  gamma _c to generate a ternary high affinity IL-2 receptor complex (7). A soluble form of IL-2 R alpha can be generated by proteolytic cleavage of the cell surface receptor, rendering the T cell unresponsive to IL-2 (8, 9). Increased serum levels of soluble IL-2 R alpha are found in some cancers and immune disorders (10). IL-2 R alpha is required for activation induced cell death (AICD) of naive T cells, a mechanism responsible for deleting autoreactive T cell clones (11, 12). IL-2 R alpha is also required for the development of CD4⁺CD25⁺ Treg which suppress autoreactive CD4⁺ T cells, thereby contributing to peripheral T cell homeostasis (11-13).

• References:

1. Minami, Y. et al. (1993) Annu. Rev. Immunol. 11:245.

2. Kovanen, P.E. and W.J. Leonard (2004) Immunol. Rev. 202:67.

3. Bluestone, J.A. and Q. Tang (2005) Curr. Opin. Immunol. 17:638.

4. Page, T.H. and M.J. Dallman (1991) Eur. J. Immunol. 21:2133.

5. Hatakeyama, M. et al. (1989) Science 244:551.

6. Takeshita, T. et al. (1992) Science 257:379.

7. Wang, X. et al. (2005) Science 310:1159.

8. Wagner, D.K. et al. (1986) J. Immunol. 137:592.

9. Schulz, O. et al. (1998) J. Exp. Med. 187:271.

10. Witkowska, A.M. (2005) Mediators Inflamm. 2005:121.

11. Willerford, D.M. et al. (1995) Immunity 3:521.

12. Van Parijs, L. et al. (1997) J. Immunol. 158:3738.

13. Almeida, A.R.M. et al. (2002) J. Immunol. 169:4850.

• Long Name:

  Interleukin 2 Receptor alpha

• Entrez Gene IDs:

  3559 (Human); 16184 (Mouse); 25704 (Rat); 403870 (Canine)

• Alternate Names:

  CD25 antigen; CD25; IDDM10; IL-2 R alpha; IL-2 receptor subunit alpha; IL2R alpha; IL-2R subunit alpha; IL2R; IL2RA; IL-2Ra; IL-2-RA; IL2-RA; interleukin 2 receptor, alpha; interleukin-2 receptor subunit alpha; p55; TAC antigen; TCGFR