SFRP3, Recombinant, Mouse (Secreted Frizzled Related Protein 3, FRZB, Fritz, Frzb1) (BSA Free)

Secreted Frizzled Related Protein 3 (sFRP-3) was originally identified in bovine cartilage for its chondrogenic ability. Human, mouse, chick and Xenopus clones have also been isolated. sFRP-3 is often referred to as FRZB, other names also include Fritz, Frzb1, and FRP-3. At the amino acid sequence level, sFRP-3 is highly conserved. The mouse protein shares 76% identity with Xenopus, and 92% with human proteins. The gene for mouse sFRP-3 has been localized to the central region of chromosome 2. Murine sFRP-3 is expressed in the primitive streak during gastrulation, as well as in the retina, foregut diverticulum, nervous system, and posterior mesoderm during development. In adult tissues, sFRP-3 expression, as determined by Northern blot, is detected in the heart, brain, spleen, skeletal muscle, kidney and testis. The N-terminal portion of sFRP-3 protein shows 50% amino acid identity to the corresponding region of the Drosophila frizzled gene product, a receptor for Wg/Wnt signals. The similarity of sFRP-3 with frizzled proteins is restricted to the N-terminal cysteine-rich domain (CRD) that contains at least ten cysteine residues with highly conserved spacing between them. sFRP-3 was subsequently shown to be a soluble antagonist of Wnt signals. It lacks all transmembrane domains of frizzled proteins but retains the ability to bind Wnts. Ectopic expression of sFRP-3 mRNA has been shown to interfere with the induction of secondary axes in Xenopus embryos injected with Xwnt-8 mRNA (Hoang et al., 1996, J. Biol. Chem. 271:26131, Leyns et al., 1997, Cell 88:747,, Wang et al., 1997, Cell 88:757, Mayr et al., 1997, Mech. Dev. 63:109, Rattner et al., 1997, PNAS 94:2859). Source: A DNA sequence encoding the mature mouse sFRP-3 protein sequence (Leyns et al., 1997, Cell, 88: 747) was fused to a 6X histidine tag at the carboxy-terminus. The fusion protein was expressed in a mouse myeloma cell line, NS0. Molecular Mass: Based on N-terminal sequencing, the mature mouse sFRP-3 protein starts at Ala33 and has a calculated molecular mass of 34kD. As a result of glycosylation, the recombinant protein migrates as an ~37kD protein in SDS-PAGE under reducing conditions. Endotoxin Level: < 1.0 EU per 1ug of the cytokine as determined by the LAL method. Activity: Measured by its ability to interfere with the axis inducing activity of Xwnt-8 mRNA in early Xenopus embryos. In a population of embryos, addition of 1ng of rmsFRP protein per embryo resulted in 50-100% reduction in number of secondary axes produced by 10-20pg of Xwnt-8 mRNA. Reconstitution: It is recommended that sterile PBS be added to the vial to prepare a working stock solution of no less than 50ug/ml. The carrier-free protein should be used immediately upon reconstitution to avoid losses in activity due to non-specific binding to the inside surface of the vial. For long term storage as a dilute solution, a carrier protein (e.g. 0.1% HSA or BSA) should be added to the vial. Storage: Lyophilized samples are stable for greater than six months at -20°C to -70°C. Upon reconstitution, this cytokine, in the presence of carrier protein, can be stored under sterile conditions at 2°-4°C for one month or at -20°C to -70°C for three months without detectable loss of activity. Avoid repeated freeze-thaw cycles.