• Purity

  >97%, 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 activate Wnt induced TCF reporter activity in HEK293 human embryonic kidney cells expressing human Frizzled-4 and human LRP-5. The ED    ₅₀ for this effect is 40-200 ng/mL.

• Source

  E. coli-derived Lys25-Ser131, with an N-terminal Met

• Accession #

• N-terminal Sequence    
  Analysis

  Met

• Structure / Form

  Disulfide-linked oligomer

• Predicted Molecular Mass

  12.3 kDa (monomer)

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: Norrin

Norrin (also called Norrie Disease Protein or NDP) is a secreted regulatory protein that remains tightly associated with the extracellular matrix (1). At least 70 mutations of human Norrin have been identified in Norrie disease (X-linked retinal dysplasia) or in a minority of X-linked familial exudative vitreoretinopathy (FEVR). Both are disorders of retinal vascularization that cause blindness (2, 3). Norrin consists of disulfide-linked homodimers that oligomerize further via disulfide bridges to form higher order oligomers containing up to ten 12 kDa units. The cysteine-rich C-terminal domain of Norrin shows homology to von Willebrand factor, several extracellular mucin proteins, and members of the TGF-beta family. Molecular modeling studies predict that Norrin assumes the cysteine-knot structure typical of the TGF-beta family (4). Although Norrin is not related to Wnt family proteins, it functions like a Wnt protein in that it binds with high affinity to the receptor Frizzled-4, requires LDL receptor-related protein (LRP) as a co-receptor, and induces activation of the canonical Wnt signaling pathway (5). Norrin and Frizzled-4 are widely expressed, but at relatively low levels, in tissues displaying vascular phenotypes. Genetic disruption of either Norrin or Frizzled-4 results in blindness and progressive deafness due to vascular abnormalties (5-7). Female Norrin  ^-/- mice are infertile due to abnormalities in decidual vasculature (8). Mature mouse Norrin shares 97-98% aa identity with human, canine and bovine Norrin.

• References:

1. Perez-Vilar, J. and R.L. Hill (1997) J. Biol. Chem. 272:33410.

2. Berger, W. et al. (1992) Nat. Genet. 1:199.

3. Berger, W. and H.H. Ropers, 2001, in “The Metabolic and Molecular Bases of Inherited Diseases”, C.R. Scriver, et al., eds., pp. 5977.

4. Meitinger, T. et al. (1993) Nat. Genet. 5:376.

5. Xu, Q. et al. (2004) Cell 116:883.

6. Hartzer, M.K. et al. (1999) Brain Res. Bull. 49:355.

7. Wang, Y. et al. (2001) J. Neurosci. 21:4761.

8. Luhmann, U.F.O. et al. (2005) Genesis 42:253.

• Entrez Gene IDs:

  4693 (Human)

• Alternate Names:

  EVR2; exudative vitreoretinopathy 2 (X-linked); FEVR; ND; NDP; Norrie disease (pseudoglioma); Norrie disease protein; Norrin; X-linked exudative vitreoretinopathy 2 protein