Recombinant Human Exostosin 1/2 Heterodimer Protein, CF

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Recombinant Human Exostosin 1/2 Heterodimer Protein, CF Summary

Learn more about Fluorescent Glycan Labeling and Detection

Product Specifications

>95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
Endotoxin Level
<1.0 EU per 1 μg of the protein by the LAL method.
Measured by its ability to transfer GlcNAc and GlcA from donor substrates to heparan sulfate. The specific activity is >225 pmol/min/μg, as measured under the described conditions.
Chinese Hamster Ovary cell line, CHO-derived human Exostosin 1/2 Heterodimer protein
Arg29-Leu746 with a C-terminal 2-His and HA tag (EXT1) & Ser53-Leu718 with a C-terminal 6-His tag (EXT2)
N-terminal Sequence
Arg29 (EXT1) & Ser53 (EXT2)
Predicted Molecular Mass

84 kDa (EXT1) & 77 kDa (EXT2)

69-85 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 Supplied as a 0.2 μm filtered solution in Tris, NaCl and Glycerol.
Shipping The product is shipped with polar packs. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage: Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
  • 6 months from date of receipt, -20 to -70 °C as supplied.
  • 3 months, -20 to -70 °C under sterile conditions after opening.

Assay Procedure

  • Glycosyltransferase Activity Kit (Catalog # EA001)
  • Assay Buffer: 25 mM Tris, 150 mM NaCl, 5 mM CaCl2,  5 mM MnCl2, pH 7.0
  • Recombinant Human Exostosin 1/2 Heterodimer (rhEXT1/2) (Catalog # 8567-GT)
  • UDP-GlcA (Sigma, Catalog # U5625), 10 mM stock in deionized water
  • UDP-GlcNAc (Sigma, Catalog # U4375), 50 mM stock in 50% ethanol/50% deionized water
  • Heparan Sulfate (Celsus Labs, Catalog # HO-03101 or HO-3105), 50 mg/mL stock in deionized water
  • 96-well Clear Plate (Catalog # DY990)
  • Plate Reader (Model: SpectraMax Plus by Molecular Devices) or equivalent
  1. Dilute 1 mM Phosphate Standard provided by the Glycosyltransferase Kit by adding 40 µL of the 1 mM Phosphate Standard to 360 µL of Assay Buffer for a 100 µM stock. This is the first point of the standard curve.
  2. Complete the standard curve by performing six one-half serial dilutions of the 100 µM Phosphate stock using Assay Buffer. The standard curve has a range of 0.078 to 5 nmol per well.
  3. Prepare a reaction mixture containing 1 mM UDP-GlcA, 1 mM UDP-GlcNAc, 8 mg/mL Heparan Sulfate, and 4 µg/mL Coupling Phosphatase 1 in Assay Buffer.
  4. Dilute rhEXT1/2 to 4 µg/mL in Assay Buffer.
  5. Load 50 µL of each dilution of the standard curve into a plate. Include a curve blank containing 50 μL of Assay Buffer.
  6. Load 25 µL of 4 µg/mL rhEXT1/2 into empty wells of the same plate as the curve. Include a Control containing 25 μL of Assay Buffer.
  7. Add 25 µL of the reaction mixture to all wells, excluding the standard curve. 
  8. Seal plate and incubate at 37 °C for 20 minutes.
  9. Add 30 µL of the Malachite Green Reagent A to all wells. Mix briefly.
  10. Add 100 µL of deionized water to all wells. Mix briefly.
  11. Add 30 µL of the Malachite Green Reagent B to all wells. Mix and incubate sealed plate for 20 minutes at room temperature.
  12. Read plate at 620 nm (absorbance) in endpoint mode.
  13. Calculate specific activity:

     Specific Activity (pmol/min/µg) =

Phosphate released* (nmol) x (1000 pmol/nmol)
Incubation time (min) x amount of enzyme (µg)

     *Derived from the phosphate standard curve using linear or 4-parameter fitting and adjusted for Control.

Per Reaction:
  • rhEXT2+rhEXT1: 0.1 µg
  • UDP-GlcA: 0.5 mM
  • UDP-GlcNAc: 0.5 mM
  • Heparan Sulfate: 200 µg
  • Coupling Phosphatase 1: 0.1 µg
Reconstitution Calculator

Reconstitution Calculator

The reconstitution calculator allows you to quickly calculate the volume of a reagent to reconstitute your vial. Simply enter the mass of reagent and the target concentration and the calculator will determine the rest.


Background: Exostosin 1/2 Heterodimer

Exostosin (EXT) family of glycosyltransferases are involved in heparan sulfate (HS) and heparin biosynthesis (1). Mutations of these enzymes are the causes of hereditary multiple exostoses, which are characterized by formation of numerous cartilage-capped, benign bone tumors (osteocartilaginous exostoses or osteochondromas) that are often accompanied by skeletal deformities and short stature (2). In a small percentage of cases exostoses have exhibited malignant transformation resulting in an osteosarcoma or chondrosarcoma (3). Five members of this family have been cloned to date: EXT1, EXT2, EXTL1, EXTL2, and EXTL3. EXT1 and EXT2 are bifunctional enzymes with both beta -1,4-glucuronyltransferase and alpha -1,4-N-acetylglucosaminyltransferase activities that elongate HS chains with alternating beta -1,4-GlcA and alpha -1,4-GlcNAc residues on the non-reducing end (4). EXT1 is an active enzyme, but the hetero-dimer of EXT1 and EXT2 has increased stability and activity (1). The enzyme activity is measured using a phosphatase-coupled assay (5).

  1. Busse, M. et al. (2007) J. Biol. Chem. 282:32802.
  2. Raskind W.H. et al. (1998) Am. J. Hum. Genet. 62:346.
  3. Hecht J.T. et al. (1997) Am. J. Hum. Genet. 60:80.
  4. Kobayashi S. et al. (2000) Biochem. Biophys. Res. Commun. 268:860.
  5. Wu, Z.L. et al. (2011) Glycobiology 21:727.
Long Name
Heterodimer of Exostosin 1 and Exostosin 2
Alternate Names
Exostosin 1/2 Heterodimer; EXT1/EXT2 Heterodimer

Citation for Recombinant Human Exostosin 1/2 Heterodimer Protein, CF

R&D Systems personnel manually curate a database that contains references using R&D Systems products. The data collected includes not only links to publications in PubMed, but also provides information about sample types, species, and experimental conditions.

1 Citation: Showing 1 - 1

  1. Imaging specific cellular glycan structures using glycosyltransferases via click chemistry.
    Authors: Wu Z, Person A, Anderson M, Burroughs B, Tatge T, Khatri K, Zou Y, Wang L, Geders T, Zaia J, Sackstein R
    Glycobiology, 2018-02-01;0(0):.
    Species: Human, Mouse
    Sample Types: Whole Cells
    Applications: Click Chemistry


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