• Purity

  >80%, 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 its ability to induce TNF-alpha secretion by THP‑1 human acute monocytic leukemia cells. The ED    ₅₀ for this effect is 6-30 μg/mL.

• Source

  Mouse myeloma cell line, NS0-derived

  Human C1q R/CD93 (Ala24-Lys580) Accession # Q9NPY3	IEGRMD	Human IgG1 (Pro100-Lys330)
  N-terminus		C-terminus

• Accession #

• N-terminal Sequence    
  Analysis

  Ala24

• Structure / Form

  Disulfide-linked homodimer

• Predicted Molecular Mass

  84.7 kDa (monomer)

• SDS-PAGE

  110-130 kDa, reducing conditions

Background: C1q R1/CD93

C1q  R1, also known as CD93 and C1q Rp, is an approximately 125 kDa transmembrane glycoprotein that is involved in various aspects of inflammatory reactions (1). Mature human CD93 consists of a 557 amino acid (aa) extracellular domain (ECD) with one C‑type lectin domain, four tandem EGF‑like domains, and a mucin‑like domain, followed by a 21 aa transmembrane segment and a 51 aa cytoplasmic domain (2, 3). Within the ECD, human CD93 shares 65% aa sequence identity with mouse and rat CD93. It is distinct from the 60 kDa Calreticulin which is likewise known as C1q  R1 (4, 5). Unlike Calreticulin, and despite its name, C1q  R1/CD93 does not appear to bind the complement protein C1q (3, 5). CD93 is expressed by vascular endothelial cells (5) and by a variety of hematopoietic cells (3‑9). Various sized fragments of soluble CD93 (50‑75 kDa) can be shed from monocytes, neutrophils, and vascular endothelial cells following inflammatory stimulation, leaving a residual stub in the membrane (11‑13). Cross‑linking of cell surface CD93 enhances phagocytosis by monocytes and enhances the uptake of apoptotic cells   in vivo (10, 15). Soluble CD93 promotes the differentiation of monocytes to macrophages, phagocytosis of apoptotic cells, and inflammatory responsiveness to multiple TLR ligands (12, 14). It is required for plasma cell longevity in the bone marrow and for the resulting extended humoral response (9).

• References:

1. Greenlee-Wacker, M.C. et al. (2012) Curr. Drug Targets 13:411.

2. Nepomuceno, R.R. et al. (1997) Immunity 6:119.

3. Steinberger, P. et al. (2002) J. Leukoc. Biol. 71:133.

4. Nepomuceno, R.R. and A.J. Tenner (1998) J. Immunol. 160:1929.

5. McGreal, E.P. et al. (2002) J. Immunol. 168:5222.

6. Lovik, G. et al. (2001) Scand. J. Immunol. 53:410.

7. Danet, G.H. et al. (2002) Proc. Natl. Acad. Sci. USA 99:10441.

8. Ikewaki, N. et al. (2010) J. Clin. Immunol. 30:723.

9. Chevrier, S. et al. (2009) Proc. Natl. Acad. Sci. USA 106:3895.

10. Norsworthy, P.J. et al. (2004) J. Immunol. 172:3406.

11. Bohlson, S.S. et al. (2005) J. Immunol. 175:1239.

12. Greenlee, M.C. et al. (2009) Inflamm. Res. 58:909.

13. Greenlee-Wacker, M.C. et al. (2011) J. Immunol. 187:3353.

14. Jeon, J.W. et al. (2010) J. Immunol. 185:4921.

15. Nepomuceno, R.R. et al. (1999) J. Immunol. 162:3583.

• Long Name:

  Complement Component C1q Receptor

• Entrez Gene IDs:

  22918 (Human); 17064 (Mouse); 84398 (Rat)

• Alternate Names:

  AA4 Antigen; C1q R1; C1q receptor 1; C1q Rp; C1q/MBL/SPA receptor; C1qR(P); C1qR1; C1qRp; CD93 antigenC1qR; CD93 molecule; CD93; CDw93C1QR1; Collectin Receptor; Complement component 1 q subcomponent receptor 1; complement component 1, q subcomponent, receptor 1; complement component C1q receptor; dJ737E23.1; ECSM3; Ly68; Matrix-remodeling-associated protein 4; matrix-remodelling associated 4; MXRA4