• Purity
  >95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
• Endotoxin Level
  <0.10 eu="" per="" 1="" μg="" of="" the="" protein="" by="" the="" lal="">
• Activity
  Measured in a competitive binding assay. WhenRecombinant Mouse Kremen‑1 (Catalog # 1647-KR)is immobilized at 4 µg/mL (100 µL/well), Recombinant Mouse Dkk-2 inhibits 50% binding of biotinylatedRecombinant Human Dkk-1 (Catalog # 5439-DK)(200 ng/mL) at the concentration range of 0.25-1.5 µg/mL.
• Source
  Spodoptera frugiperda, Sf 21 (baculovirus)-derived Ser26-Ile259, with Leu35Pro substitution and a C-terminal 10-His tag
• Accession #
  Q9QYZ8.1
• N-terminal Sequence
  Analysis
  Ser26
• Predicted Molecular Mass
  27 kDa
• SDS-PAGE
  29-35 kDa, reducing conditions

• References:
  1. Monaghan, A.P. et al. (1999) Mech. Dev. 87:45.
  2. Krupnik, V.E. et al. (1999) Gene 238:301.
  3. Niehrs, C. (2006) Oncogene 25:7469.
  4. Chen, L. et al. (2008) J. Biol. Chem. 283:23364.
  5. Wu, W. et al. (2000) Current Biol. 10:1611.
  6. Mao, B. et al. (2001) Nature 411:321.
  7. Li, L. et al. (2002) J. Biol. Chem. 277:5977.
  8. Brott, B. and S.Y. Sokol (2002) Mol. Cell. Biol. 22:6100.
  9. Mao, B. et al. (2002) Nature 417:664.
  10. Mao, B. and C. Niehrs (2003) Gene 302:179.
  11. Zhang, Y. et al. (2009) J. Reprod. Dev. 55:17.
  12. Li, X. et al. (2005) Nat. Genet. 37:945.
  13. van der Horst, G. et al. (2005) J. Bone Miner. Res. 20:1867.
  14. Mukhopadhyay, M. et al. (2006) Development 133:2149.
  15. Gage, P.J. et al. (2008) Dev. Biol. 317:310.
• Long Name:
  Dickkopf-2
• Entrez Gene IDs:
  27123 (Human); 56811 (Mouse)
• Alternate Names:
  dickkopf (Xenopus laevis) homolog 2; dickkopf 2; dickkopf homolog 2 (Xenopus laevis); dickkopf related protein-2; dickkopf-2; dickkopf-related protein 2; Dkk2; Dkk-2; hDkk-2

Background:

Dickkopf related protein 2 (Dkk-2) is a member of the Dickkopf family of secreted Wnt modulators (1-3). Dkk proteins contain a signal peptide and two conserved cysteine-rich domains that are separated by a linker region. The second cysteine-rich domain mediates Dkk-2 binding activities, and its interaction with LRP beta propellers has been mapped (2-4, 7). The 226 aa, ~35 kDa mature mouse Dkk-2 shares  99%, 96%, 96%, 96% and 94% aa identity with rat, human, dog, horse and cow Dkk-2, respectively, and can activate the canonical Wnt signaling pathway in Xenopus embryos (5). Dkk proteins modify Wnt engagement of a receptor complex composed of a Frizzled protein and a low-density lipoprotein receptor-related protein, either LRP5 or LRP6 (3). When LRP6 is over-expressed, direct high-affinity binding of Dkk-2 to LRP can enhance canonical Wnt signaling (6-8). However, when Dkk-2 and LRP6 form a ternary complex with Kremen2, Wnt signaling is inhibited due to internalization of Dkk-2/LRP6/Krm2 complexes (9, 10). Thus, depending on the cellular context, Dkk-2 can either activate or inhibit canonical Wnt signaling (3). In contrast, binding of Dkk-1 or Dkk-4 to LRP is consistently antagonistic (3). Dkk proteins are expressed in mesenchymal tissues and control epithelial transformations. Dkk-2 expression has been studied most in bone and eye, although it is expressed as early as periimplantation in mice (11). Mouse Dkk-1 or Dkk-2 deficiencies have opposite effects on bone homeostasis, despite down-regulating Wnt antagonism in both cases (12, 13). Dkk-2 expression is induced by Wnts in bone, and is thought to enhance bone density by promoting terminal differentiation of osteoblasts and mineral deposition (12). In contrast, Dkk-1 negatively regulates late osteoblast proliferation, which limits bone density (13). Dkk-2-deficient mice are blind, exhibiting faulty differentiation of corneal epithelium and ectopic blood vessels in the periocular mesenchyme (14, 15).

      R&D Systems位于美国的明尼苏达州，一直致力于生物制品的开发与生产。公司成立之初主要生产用于医院及临床应用的血控品。1997年，公司推出第一个产品--富血小板血浆质控品；1981年，公司成为全球第二家生产含血小板全血控品的供应商。40多年的发展中，R&D Systems仍持续开发各种血控品产品。  1985年，作为公司推出的第一个科研试剂产品，也是全球第一家将该产品进行商业化生产的产品，R&D Systems成功上市了TGF-beta1蛋白。作为胞外信号分子，TGF-beta1蛋白在多种细胞中进行表达，并作为胞外信号分子参与免疫功能，细胞增殖和细胞分化等生物学过程。该产品推出后，公司陆续从生物材料中纯化了几种细胞因子产品并推向市场。  天然蛋白类产品的成功推广，加速了R&D Systems在细胞因子市场的开拓。公司于1985年形成Growth Factor事业部（现Biotechnology事业部）。Biotechnology事业部的目标是生产和营销重组人细胞因子。与天然来源提取蛋白相比较，DNA重组技术生产的蛋白产品其成本更低，产量更高，完全摆脱原料的限制。1989年，Biotechnology事业部开始开发抗细胞因子的单克隆和多克隆抗体，并于1990年开发了第一个ELISA试剂盒。  2014年2月10日，R&D Systems的母公司宣布命名为Bio-Techne. Bio-Techne旗下包括R&D Systems, Novus Biologicals, BiosPacific, Tocris Bioscience, Boston Biochem和Bionostics。