• 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 its ability to inhibit Wnt-3a-induced alkaline phosphatase production by MC3T3?E1 mouse preosteoblast cells. The ED    ₅₀ for this effect is 15-75 ng/mL in the presence of 10 ng/mL of Recombinant Mouse Wnt?3a (Catalog # ) Measured by its binding ability in a functional ELISA. In a 100 μL reaction mixture containing biotinylated recombinant mouse (rm) Wnt-3a or rmWnt-5a at 50-100 ng/mL and Recombinant Human (rh) Frizzled-8 Fc Chimera dilutions at 0.1-8,000 ng/mL, the concentration of rhFrizzled-8 Fc Chimera that produces 50% of the optimal binding response is found to be approximately 7-28 ng/mL.    
     Optimal concentrations should be determined by each laboratory for each application.  

• Source

  Chinese Hamster Ovary cell line, CHO-derived

  Human Frizzled-8 (Ala25-Pro172) Accession # Q9H461	IEGRMD	Human IgG1 (Pro100-Lys330)
  N-terminus		C-terminus

• Accession #

• N-terminal Sequence    
  Analysis

  Ala25 & Ala28    
   

• Structure / Form

  Disulfide-linked homodimer    
   

• Predicted Molecular Mass

  43.3 kDa (monomer)

• SDS-PAGE

  55-65 kDa, reducing conditions

Background: Frizzled-8

Frizzled-8 is one of at least ten seven-transmembrane (7TM) glycoproteins of the Frizzled family of Wnt receptors (1-2). Frizzled proteins are thought to be G-protein-coupled (1). Wnt engagement, with low density lipoprotein receptor-related proteins LRP-5 or LRP-6 acting as co-receptors, stabilizes beta -catenin and promotes gene transcription that is important in development and tissue maintenance (1). Human Frizzled-8 cDNA encodes 694 amino acids (aa) including a 27 aa signal peptide, a 247 aa extracellular domain (ECD), the 7TM region (aa 276-605), and a C-terminal cytoplasmic domain with a PDZ binding motif (aa 606-694) (2). The ECD includes a cysteine-rich region (CRD, aa 30-151) that binds Wnts and is highly conserved among Frizzleds, and a linker region. Within aa 28-172, human Frizzled-8 shares 99%, 99%, 90% and 85% aa identity with mouse, rat, Xenopus and zebrafish Frizzled-8, respectively. It also shares 82% aa identity with human Frizzled-5. Frizzleds can form homodimers or selective hetero-oligomers with other family members, which can involve the TM regions and possibly the CRD (1, 3). During mouse development, Frizzled-8 is expressed in tissues that are important for organizing the anterior-posterior axis (4). Interactions of Frizzled-8 with several non-Wnt ligands have been identified. Interaction with Frizzled-8 and LRP-6 allows R-spondins to activate beta -catenin signaling pathways, while interaction with IGFBP-4 (insulin-like growth factor binding protein (4) or CTGF (connective tissue growth factor) inhibits Wnt signaling (5-7). These ligands bind the extracellular CRD of Frizzled-8, blocking Wnt binding. The recombinant Frizzled-8 CRD has also been used to block Wnt signaling and inhibit growth of teratocarcinomas (5-10).

• References:

1. Schulte, G. and V. Bryja (2007) Trends Pharmacol. Sci. 28:518.

2. Saitoh, T. et al. (2001) Int. J. Oncol. 18:991.

3. Dann, C.E. et al. (2001) Nature 412:86.

4. Lu C.C. et al. (2004) Gene Expr. Patterns 4:569.

5. Nam, J-S. et al. (2006) J. Biol. Chem. 281:13247.

6. Zhu, W. et al. (2008) Nature 454:345.

7. Mercurio, S. et al. (2004) Development 131:2137.

8. Chesnutt, C. et al. (2004) Dev. Biol. 274:334.

9. Yamashita, J.K. et al. (2005) FASEB J. 19:1534.

10. DeAlmeida, V.I. et al. (2007) Cancer Res. 67:5371.

• Entrez Gene IDs:

  8325 (Human); 14370 (Mouse)

• Alternate Names:

  frizzled (Drosophila) homolog 8; frizzled 8; frizzled family receptor 8; frizzled homolog 8 (Drosophila); Frizzled8; Frizzled-8; FZ-8; FZD8; hFZ8