Recombinant Human Klotho beta Protein, CF

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Product Details
Citations (6)
Reviews (3)

Recombinant Human Klotho beta Protein, CF Summary

Product Specifications

>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 method.
Measured by its binding ability in a functional ELISA. When Recombinant Human FGF-21 (Catalog # 2539-FG) is immobilized at 1 µg/mL (100 µL/well), Recombinant Human Klotho beta His-tag (Catalog # 5889-KB) binds with an ED50 of 2.5-20 ng/mL.
Mouse myeloma cell line, NS0-derived human Klotho beta protein
Phe53-Leu997, with a C-terminal 10-His tag
Accession #
N-terminal Sequence
Predicted Molecular Mass
110 kDa
113 - 125 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 PBS, Glycerol and EDTA.
Shipping The product is shipped with dry ice or equivalent. 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, -70 °C as supplied.
  • 1 month, 2 to 8 °C under sterile conditions after opening.

Scientific Data

Binding Activity View Larger

When Recombinant Human FGF-21 (2539-FG) is immobilized at 1 µg/mL (100 µL/well), Recombinant Human Klotho beta His-tag (Catalog # 5889-KB) binds with an ED50 of 2.5-20 ng/mL.

SDS-PAGE Recombinant Human Klotho beta Protein SDS-PAGE View Larger

1 μg/lane of Recombinant Human Klotho beta was resolved with SDS-PAGE under reducing (R) and non-reducing (NR) conditions and visualized by Coomassie® Blue staining, showing a single band at 113-125 kDa.

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Background: Klotho beta

Klotho beta, a divergent structural member of the glycosidase I superfamily, is expressed primarily in the liver and pancreas, with lower expression in adipose tissue (1, 2). Like Klotho, Klotho beta facilitates binding between FGF19 subfamily members and their receptors via formation of a ternary complex (3). The Klotho beta mediated interaction of human FGF19 (mouse FGF15) with FGF Receptor 4 in the liver negatively regulates bile acid synthesis by controlling the secretion of two key bile acid synthase genes, cholesterol 7-alpha hydroxylase (Cyp7a1) and sterol 12-alpha hydroxylase (Cyp8b1) (2-5). Klotho beta is also a cofactor for the interaction of FGF21 with FGF Receptor 1c in adipocytes, which allows FGF21 to stimulate GLUT1 expression, upregulating adipocyte insulin-dependent glucose uptake (2-4, 6). The 1043 amino acid (aa) type I transmembrane protein is composed of a 51 aa signal sequence, a 943 aa extracellular domain (ECD) containing two glycosidase-like regions, a 21 aa transmembrane domain, and 28 aa intracellular tail. Since Klotho-related proteins lack critical active site Glu residues present in beta -glycosidases, it was initially unclear whether they were functional enzymes (1, 7). However, glucuronidase activity has since been demonstrated for Klotho, indicating that physiologically relevant enzymatic activity for Klotho beta is also possible (8). The extracellular domain shares 79%, 87%, 87% and 67% identity with mouse, equine, canine and rat Klotho beta, respectively. The low identity with rat reflects aa discordance within rodent ECD.

  1. Mian, I. S. (1998) Blood Cells Mol. Dis. 24:83.
  2. Kurosu, H. and M. Kuro-o (2009) Mol. Cell. Endocrinol. 299:72.
  3. Ito, S. et al. (2005) J. Clin. Invest. 115:2202.
  4. Kurosu, H. et al. (2007) J. Biol. Chem. 282:26687.
  5. Lin, B. C. et al. (2007) J. Biol. Chem. 282:27277.
  6. Ogawa, Y. et al. (2007) Proc. Natl. Acad. Sci USA 104:7432.
  7. Chang, Q. et al. (2005) Science 310:490.
  8. Goetz, R. et al. (2007) Mol. Cell. Biol. 27:3417.
Entrez Gene IDs
152831 (Human); 83379 (Mouse); 289625 (Rat); 102147155 (Cynomolgus Monkey)
Alternate Names
betaKlotho; beta-klotho; BKL; KLB; klotho beta like; Klotho beta; klotho beta-like protein; MGC142213

Citations for Recombinant Human Klotho beta 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.

6 Citations: Showing 1 - 6
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  1. Heating-mediated purification of active FGF21 and structure-based design of its variant with enhanced potency
    Authors: YE Jung, KW Lee, JH Cho, DW Bae, BG Jeong, YJ Jung, SB Park, YJ An, K Kim, GS Lee, LW Kang, JH Moon, JH Lee, EK Kim, HS Yim, SS Cha
    Scientific Reports, 2023;13(1):1005.
    Species: Human
    Sample Types: Protein
    Applications: SPR
  2. Curtailing FGF19's mitogenicity by suppressing its receptor dimerization ability
    Authors: J Niu, J Zhao, J Wu, G Qiao, J Gu, C Zhou, Q Li, L Ying, D Wang, H Lin, X Li, M Mohammadi, Z Huang
    Proc Natl Acad Sci U S A, 2020;0(0):.
    Species: Human
    Sample Types: Protein
    Applications: SPR
  3. betaKlotho is identified as a target for theranostics in non-small cell lung cancer
    Authors: F Li, X Li, Z Li, W Ji, S Lu, W Xia
    Theranostics, 2019;9(25):7474-7489.
  4. Molecular elements in FGF19 and FGF21 defining KLB/FGFR activity and specificity
    Authors: A Agrawal, S Parlee, D Perez-Tilv, P Li, J Pan, PA Mroz, AM Kruse Hans, B Andersen, B Finan, A Kharitonen, RD DiMarchi
    Mol Metab, 2018;13(0):45-55.
    Species: Human
    Sample Types: Protein
    Applications: Bioassay
  5. The transcription factor MITF is a critical regulator of GPNMB expression in dendritic cells.
    Authors: Gutknecht M, Geiger J, Joas S, Dorfel D, Salih H, Muller M, Grunebach F, Rittig S
    Cell Commun Signal, 2015;13(0):19.
    Species: Human
    Sample Types: Whole Cells
    Applications: Control
  6. Widespread potential for growth-factor-driven resistance to anticancer kinase inhibitors.
    Authors: Wilson TR, Fridlyand J, Yan Y, Penuel E, Burton L, Chan E, Peng J, Lin E, Wang Y, Sosman J, Ribas A, Li J, Moffat J, Sutherlin DP, Koeppen H, Merchant M, Neve R, Settleman J
    Nature, 2012;487(7408):505-9.
    Species: Human
    Sample Types: Whole Cells
    Applications: Bioassay


  1. Why is an antibody used to immobilize Recombinant Human Klotho-beta protein, Catalog # 5889-KB, in the binding assay as described in the insert?

    • The Recombinant Human Klotho-beta protein is formulated in PBS, 50%(v/v) Glycerol and 0.1 mM EDTA, pH 6.8.  This formulation results in lower efficiency of binding of the protein by itself and therefore an antibdy is used to immobilize the protein. Additionally, the protocol as described is more sensitive for detection of FGF-21 binding. 

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Recombinant Human Klotho beta Protein, CF
By Anonymous on 12/20/2020
Application: Binding assay/Protein-protein interaction

Recombinant Human Klotho beta Protein, CF
By Anonymous on 12/06/2020
Application: Immunoassay Standard

Recombinant Human Klotho beta Protein, CF
By komal patel on 07/27/2020
Application: Binding assay/Protein-protein interaction