• Purity

  >90%, 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 Wnt-3a-induced alkaline phosphatase production by MC3T3?E1 mouse preosteoblast cells. The ED    ₅₀ for this effect is 1-5 μg/mL in the presence of Recombinant Mouse Wnt?3a (Catalog # ).

• Source

  Mouse myeloma cell line, NS0-derived Gln24-Tyr211 with an N-terminal 7-His tag

• Accession #

• N-terminal Sequence    
  Analysis

  His    
   

• Predicted Molecular Mass

  22 kDa

• SDS-PAGE

  30 kDa, reducing conditions

Carrier Free

What does CF mean?

CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our recombinant proteins. Adding a carrier protein enhances protein stability, increases shelf-life, and allows the recombinant protein to be stored at a more dilute concentration. The carrier free version does not contain BSA.

What formulation is right for me?

In general, we advise purchasing the recombinant protein with BSA for use in cell or tissue culture, or as an ELISA standard. In contrast, the carrier free protein is recommended for applications, in which the presence of BSA could interfere.

Background: SOST/Sclerostin

SOST, also known as sclerostin, is a member of the cerberus/DAN family, a group of secreted glycoproteins characterized by a cysteine-knot motif. Cerberus/DAN family members are putative BMP antagonists, and include Dan, Cerberus, Gremlin, PRDC, and Caronte. While the overall sequence identity between members of the family is low, they have conserved spacing of six cysteine residues. Cerberus and Dan have an additional cysteine residue used for dimerization; however, SOST does not and is secreted as a monomer. SOST was originally identified as an important regulator of bone homeostasis. Positional cloning studies identified that mutations in the SOST gene can cause sclerosteosis and van Buchem disease, bone dysplasia disorders characterized by progressive skeletal overgrowth. Significant levels of SOST expression are detected in bone, cartilage, kidney, and liver. SOST is expressed by osteoclasts in developing bones of mouse embryos, including both intramembranously forming skull bones and endochondrally forming long bones. SOST plays a physiological role as a negative regulator of bone formation by repressing BMP-induced osteogenesis. SOST has been shown to have unique ligand specificity, binding BMP-5, -6, and -7 with high affinity and BMP-2 and -4 with low affinity. This seems to be the first example of a BMP antagonist being localized to osteoclasts, cells derived from the hematopoietic lineage, that function to degrade bone matrix. Recombinant human SOST preparations from R&D Systems bind BMP-5 and BMP-6 in a functional ELISA. Human and mouse SOST share 88% amino acid identity (1-3).

• References:

1. Kusu, N. et al. (2003) J. Biol. Chem. 278:24113.

2. Balemans, W. et al. (2001) Hum. Mol. Genet. 10:537.

3. Brunkow, M.E. et al. (2001) Am. J. Hum. Genet. 68:577.

• Entrez Gene IDs:

  50964 (Human); 74499 (Mouse)

• Alternate Names:

  sclerostin; SOST; VBCHsclerosteosis