Recombinant Human FAM20B Protein, CF

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R&D Systems Recombinant Proteins and Enzymes
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Product Details

Recombinant Human FAM20B Protein, CF Summary

Product Specifications

>95%, by SDS-PAGE with silver staining
Endotoxin Level
<0.10 EU per 1 μg of the protein by the LAL method.
Measured by its ability to enhance survival of ATDC5 mouse chondrogenic cells. The ED50 for this effect is 0.8-4 μg/mL. Measured by its ability to phosphorylate D-xylose. The specific activity is >15 pmol/min/μg, as measured under the described conditions.
Chinese Hamster Ovary cell line, CHO-derived human FAM20B protein
Asn27-Leu409, with an N-terminal HA tag
Accession #
N-terminal Sequence
Predicted Molecular Mass
44 kDa
44-53 kDa, reducing conditions

Product Datasheets

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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.


Formulation Lyophilized from a 0.2 μm filtered solution in Tris and NaCl.
Reconstitution Reconstitute at 500 μg/mL in 25 mM Tris-HCl, pH7.5.
Shipping The product is shipped at ambient temperature. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage: Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
  • 12 months from date of receipt, -20 to -70 °C as supplied.
  • 1 month, 2 to 8 °C under sterile conditions after reconstitution.
  • 3 months, -20 to -70 °C under sterile conditions after reconstitution.
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Background: FAM20B

FAM20B is a member of the FAM20 protein family that has three members in mammals (FAM20A, FAM20B, FAM20C) (1). Human FAM20B shares 97% amino acid sequence identity with mouse and rat FAM20B. FAM20B localizes to the Golgi apparatus where it phosphorylates the xylose residue in the glycosaminoglycan (GAG)-protein linkage region of proteoglycans, which leads to enhanced GAG biosynthesis (2). Accordingly, chondroitin sulfate and heparan sulfate production is increased when FAM20B is over-expressed and reduced following FAM20B knockdown (2). FAM20B knockout mice display embryonic lethality at day E13.5, suggesting that FAM20B has an important role during development (3). Furthermore, in zebrafish, FAM20B mutations result in reduced cartilage matrix production and skeletal defects (4). The enzymatic activity of recombinant human FAM20B is measured using a phosphatase-coupled method (5).

  1. Nalbant, D. et al. (2005) BMC Genomics 6:11.
  2. Koike, T. et al. (2009) Biochem. J. 421:157.
  3. Vogel, P. et al. (2012) Vet. Pathol. 49:998.
  4. Eames, B.F. et al. (2011) PLoS Genet. 7:e1002246.
  5. Wu, Z.L. (2011) PLoS One 6:e23172.
Long Name
Family with Sequence Similarity 20, Member B
Entrez Gene IDs
9917 (Human); 215015 (Mouse); 304885 (Rat)
Alternate Names
EC 2.7.1.-; FAM20B; family with sequence similarity 20, member B; Glycosaminoglycan Xylosylkinase; gxk1; KIAA0475; Protein FAM20B; XYLK; Xylose Kinase


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