| Secreted Frizzled Related Proteins (sFRPs) are a family of vertebrate proteins which contain homology to the ligand-binding domain of the Frizzled family of transmembrane receptors. The sFRPs are approximately 30-35kD in size and are comprised of 3 domains: a signal sequence, a cysteine-rich domain (CRD) of about 110 amino acids (aa) with high degree of similarity to the Frizzled proteins, including 10 conserved cysteines, and a 175aa conserved hydrophilic carboxy terminal region. Because sFRPs contain a CRD very similar to the region responsible for binding Wnt ligands in Frizzleds, sFRPS are thought to act as soluble antagonists of Wnt signals. sFRP-2, also known as SARP-1, SDF-5, and FRP-2, is expressed during mouse embryogenesis in the eye, brain, neural tube, craniofacial mesenchyme, joints, testis, pancreas, kidney and regions of smooth muscle cell development. Expression in the adult animal has been detected in the eye, heart, lung, along with preadipose and adipose tissues in mice and humans. Mouse and human sFRP-2 proteins share 98% amino acid identity, and related proteins have also been identified in chick, rabbit, and frog. A variety of activities have been reported for sFRP-2 including an increased resistance to apoptosis, antagonism of Xwnt -8 signaling in Xenopus, regulation of Wnt-4 signaling (with sFRP-1) in renal organogenesis, and inhibition of the migration of glioma cells (1-7). Recombinant protein corresponding to Leu25-Cys295 from mouse SFRP2 with a C-terminal 6-His tag expressed in NSO cells (AAB70795). Molecular Mass: Based on N-terminal sequencing, mature rmsFRP-2 has Leu 25 at the amino terminus. The monomeric rmsFRP-2 has a calculated mass of ~31.6kD. As a result of glycosylation the recombinant protein migrates with an apparent mass of approximately 35-40kD in SDS-PAGE under reducing conditions. Activity: Measured by its ability to compete for the binding of rmFrizzled-1 and biotinylated rmWnt-3a. rmsFRP-2 has an IC 50 value of 0.7-3.5nM, under conditions in which rmFrizzled-1/Fc is present at 5.4nM, and biotinylated rmWnt-3a concentration is 2.7nM. Storage and Stability: Lyophilized powder may be stored at -20C. Stable for 12 months at -20C. Reconstitute with sterile PBS. Aliquot to avoid repeated freezing and thawing. Store at -20C. Reconstituted product is stable for 6 months at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer. |
