• Purity

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

• Endotoxin Level

  <0.10 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured by the ability of the immobilized protein to support the adhesion of HeLa human cervical epithelial carcinoma cells. When 5 x 10    ⁴ cells per well are added to Recombinant Mouse CD74 coated plates, cell adhesion is enhanced in a dose dependent manner. The ED    ₅₀ for this effect is 0.3-1.5 μg/mL.    
     Optimal dilutions should be determined by each laboratory for each application.  

• Source

  Chinese Hamster Ovary cell line, CHO-derived Gln56-Leu215, with an N-terminal HA-tag (YPYDVPDYA)

• Accession #

• N-terminal Sequence    
  Analysis

  Tyr

• Predicted Molecular Mass

  19.4 kDa

• SDS-PAGE

  26-40 kDa, reducing conditions

Background: CD74

CD74, also known as Invariant chain (Ii) and p33, is a type 2 transmembrane glycoprotein that plays an important role in adaptive immunity, inflammation, and cancer (1). Mature mouse CD74 consists of a 29 amino acid (aa) cytoplasmic domain, a 29 aa transmembrane segment, and a 224 aa extracellular domain (ECD) that contains one thyroglobulin type 1 domain (2). Alternate splicing generates a short isoform that lacks the thyroglobulin domain (2). Within the ECD, mouse CD74 shares 75% and 88% aa sequence identity with human and rat CD74, respectively. CD74 functions as a chaperone for MHC class II molecules on antigen presenting cells and undergoes progressive proteolysis during class II trafficking and antigenic peptide loading (3). Full length CD74 assembles into trimers which then associate with class II molecules in nonameric complexes on the cell surface (4, 5). CD74 also associates with CD44 and binds with high affinity to the cytokine MIF, leading to inflammatory leukocyte responses, protection from tissue fibrosis, B cell proliferative and survival signaling, and the up‑regulation of angiogenic factors in endometrial stromal cells (6‑11). MIF binding notably induces the proteolytic cleavage of the CD74 intracellular domain which then promotes B cell differentiation (10). CD74 is up‑regulated on non‑immune cells at sites of inflammation including amyloid beta plaques and atherosclerotic plaques (12, 13). It is also up‑regulated in a variety of cancers and enhances tumorigenicity, tumor angiogenesis, and metastasis (1, 14).

• References:

1. Beswick, E.J. and V.E. Reyes (2009) World J. Gastroenterol. 15:2855.

2. Koch, N. et al. (1987) EMBO J. 6:1677.

3. Riberdy, J.M. et al. (1992) Nature 360:474.

4. Koch, N. et al. (1991) J. Immunol. 147:2643.

5. Roche, P.A. et al. (1991) Nature 354:392.

6. Leng, L. et al. (2003) J. Exp. Med. 197:1467.

7. Takahashi, K. et al. (2009) Respir. Res. 10:33.

8. Heinrichs, D. et al. (2011) Proc. Natl. Acad. Sci. 104:17444.

9. Shi, X. et al. (2006) Immunity 25:595.

10. Gore, Y. et al. (2008) J. Biol. Chem. 283:2784.

11. Veillat, V. et al. (2010) J. Clin. Endocrinol. Metab. 95:E403.

12. Bryan, K.J. et al. (2008) Mol. Neurodegen. 3:13.

13. Martin-Ventura, J.L. et al. (2009) Cardiovasc. Res. 83:586.

14. Liu, Y.-H. et al. (2008) J. Immunol. 181:6584.

• Entrez Gene IDs:

  972 (Human); 16149 (Mouse); 25599 (Rat)

• Alternate Names:

  CD74 antigen (invariant polypeptide of major histocompatibility complex, classII antigen-associated); CD74 antigen; CD74 molecule, major histocompatibility complex, class II invariant chain; CD74; CLIP; DHLAG; DHLAGgamma chain of class II antigens; HLA class II histocompatibility antigen gamma chain; HLADG; HLA-DR antigens-associated invariant chain; HLA-DR-gamma; Ia antigen-associated invariant chain; Ia-associated invariant chain; Ia-gamma; Ii; INVG34; MHC HLA-DR gamma chain; p33