• Species Reactivity

  Human

• Specificity

  Detects human CD55/DAF in direct ELISAs and Western blots. In direct ELISAs and Western blots, no cross‑reactivity with recombinant human CD97 is observed.

• Source

  Monoclonal Mouse IgG    _2B Clone # 278803

• Purification

  Protein A or G purified from hybridoma culture supernatant

• Immunogen

  NS0-derived recombinant human CD55/DAF    
  Asp35-Ser353    
  Accession # P08174.4

• Formulation

  Lyophilized from a 0.2 μm filtered solution in PBS with Trehalose. *Small pack size (SP) is supplied as a 0.2 µm filtered solution in PBS.

• Endotoxin Level

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

• Label

  Unconjugated

Applications

• Recommended    
  Concentration

  Sample

• Western Blot

  1 µg/mL

  Recombinant Human CD55/DAF (Catalog # ) under non-reducing conditions only

• 
  

• Neutralization

  Measured by its ability to neutralize CD55-mediated adhesion of human red blood cells. Hamann, J.     et al. (1996) J. Exp. Med.     184:1185. The Neutralization Dose (ND    ₅₀) is typically 0.5-2 µg/mL in the presence of 5 µg/mL Recombinant Human CD97.

Please Note: Optimal dilutions should be determined by each laboratory for each application.  are available in the Technical Information section on our website.

Data Examples

Preparation and Storage

• Reconstitution

  Reconstitute at 0.5 mg/mL in sterile PBS.

• Shipping

  The product is shipped at ambient temperature. Upon receipt, store it immediately at the temperature recommended below. *Small pack size (SP) is shipped with polar packs. Upon receipt, store it immediately at -20 to -70 °C

• Stability & Storage

  Use a manual defrost freezer and avoid repeated freeze-thaw cycles.    

• 12 months from date of receipt, -20 to -70 °C as supplied.

• 1 month, 2 to 8 °C under sterile conditions after reconstitution.

• 6 months, -20 to -70 °C under sterile conditions after reconstitution.

Background: CD55/DAF

CD55, also known as DAF or decay-accelerating factor, is a 70‑75 kDa member of the RCA family of proteins. Human RCA (regulators of complement/C’ activation) proteins are products of chromosome 1 genes that are ubiquitously expressed on cells exposed to plasma complement proteins (1‑4). A hallmark of RCA proteins is the presence of 4 to 30 SCRs (short consensus repeats; also called CCPs for C’ control protein modules) in their plasma-exposed regions. SCRs are a 60‑65 amino acid (aa) module that contains a highly conserved Trp residue and two internal disulfide bonds that create a beta -barrel structure (1). Human CD55 is synthesized as a 381 aa precursor that contains a 34 aa signal sequence, a 319 aa mature region and a 28 aa C-terminal prosegment (5, 6). The mature region contains four SCR modules and a C-terminal O-glycosylated extension (7). Following cleavage of the prosegment, a serine is exposed that serves as an anchor for a GPI-linkage (8). Multiple polymorphisms are found in the molecule. Alternate splicing also exists. One form that may not be translated shows an intron insertion in the prosegment, resulting in a 79 aa substitution for the standard C-terminal 20 aas of the prosegment (6). Another form generates a truncated 199 aa precursor that cannot be membrane-bound and may not be secreted (9). Mature human CD55 shares 53% and 84% aa identity with mouse and monkey CD55, respectively. CD55 is known to bind CD97 via the first SCR (4). It also binds physiologically-generated C3 convertases with its second and third SCRs (7, 10). Binding results in an accelerated “decay”, or dissociation of active C3 convertases, thus blocking the development of C’ attack complexes on nonforeign cells (1, 2). Finally, viruses and bacteria are also known to use multiple SCR sites for infection (4).

• References:

1. Herbert, A. et al. (2002) Biochem. Soc. Trans. 30:990. 

2. Miwa, T. and W-C. Song (2001) Int. Immunopharmacol. 1:445. 

3. Hourcade, D. et al. (2000) Immunopharmacology 49:103. 

4. Lea, S. (2002) Biochem. Soc. Trans. 30:1014. 

5. Medof, M.E. et al. (1987) Proc. Natl. Acad. Sci. USA 84:2007. 

6. Caras, I.W. et al. (1987) Nature 325:545.

7. Lukacik, P. et al. (2004) Proc. Natl. Acad. Sci. USA 101:1279.

8. Moran, P. et al. (1991) J. Biol. Chem. 266:1250.

9. Lublin, D.M. et al. (1994) Blood 84:1276.

10. Williams, P. et al. (2003) J. Biol. Chem. 278:10691.

• Entrez Gene IDs:

  1604 (Human); 13136 (Mouse)

• Alternate Names:

  CD55 antigen; CD55 molecule, decay accelerating factor for complement (Cromer blood group); CD55; CR; CRdecay accelerating factor for complement (CD55, Cromer blood group system); CROMDAFcomplement decay-accelerating factor; DAF; decay accelerating factor for complement; TC