Recombinant Human RBP4 Protein, CF

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R&D Systems Recombinant Proteins and Enzymes
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Product Details
Citations (2)

Recombinant Human RBP4 Protein, CF Summary

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 bind all-trans retinoic acid. The binding of retinoic acid results in the quenching of Trp fluorescence in RBP4. >1.0 µM all-trans retinoic acid is bound under the described conditions.
Mouse myeloma cell line, NS0-derived human RBP4/Retinol-Binding Protein 4 protein
Glu19-Leu201, with a C-terminal Ile and 6-His tag
Accession #
N-terminal Sequence
Predicted Molecular Mass
22 kDa
22 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 sterile 50 mM Tris, 10 mM CaCl2 and 150 mM NaCl, pH 7.5.
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.
  • 6 months from date of receipt, -20 to -70 °C as supplied.
  • 3 months, -20 to -70 °C under sterile conditions after reconstitution.

Assay Procedure

  • Assay Buffer: 50 mM Tris, 10 mM CaCl2, 150 mM NaCl, pH 7.5 (TCN)
  • Recombinant Human RBP4/Retinol‑Binding Protein 4 (rhRBP4) (Catalog # 3378-LC)
  • 95% Ethanol
  • Retinoic Acid (Tocris, Catalog # 0695), 50 mM stock in DMSO
  • F16 Black Maxisorp Plate (Nunc, Catalog # 475515)
  • Fluorescent Plate Reader (Model: SpectraMax Gemini EM by Molecular Devices) or equivalent
  1. Dilute rhRBP4 to 49 µg/mL in Assay Buffer.
  2. Make serial dilutions of retinoic acid in 95% ethanol at 100, 30, 10, 3 and 1 µM.
  3. The formation of Protein/Retinol binding in microtubes:
    1. Mix 112.5 µL of 49 µg/mL rhRBP4 and 12.5 µL of retinoic acid serial dilutions in microtubes.
    2. For a blank, mix 112.5 µL of 49 µg/mL rhRBP4 and 12.5 µL of 95% ethanol in a microtube.
  4. Incubate reaction tubes at room temperature for 30 minutes.
  5. In a plate load 100 µL of the reaction mixtures and blank.
  6. Read at excitation and emission wavelengths of 280 nm and 340 nm (top read), respectively, in endpoint mode.
  7. Calculate concentration at which 50% quenching of rhRBP4 is achieved by plotting raw RFUs vs. concentration of retinoic acid with 4‑PL fitting. Use this value to estimate the concentration of retinoic acid fully bound by the rhRBP4.
Per Well:
  • rhRBP4: 4.41 µg
  • Retinoic Acid Curve: 10, 3, 1, 0.3 and 0.1 µM
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: RBP4/Retinol-Binding Protein 4

Retinol (also known as vitamin A) is unstable and insoluble in the aqueous solution (1, 2). However, retinol becomes quite stable and soluble in plasma due to its tight interaction with retinol-binding protein 4 (RBP4), also known as plasma retinol-binding protein. A prototypic member of the lipocalin superfamily, RBP4 has a beta -barrel structure with a well-defined cavity. It is secreted from the liver, a process requiring the availability of retinol. RBP4 delivers retinol from the liver to the peripheral tissues. In plasma, the RBP4-retinol complex interacts with transthyretin (TTR), also known as thyroxine-binding protein and prealbumin. The retinol-RBP4-TTR complex prevents the loss of RBP4 by filtration through the kidney and increases the stability of the retinol-RBP4 complex. Defects in RBP4 cause retinol-binding protein deficiency, which affects night vision.

  1. Zanotti, G. and R. Berni. (2004) Vitamins and Hormones 69:271.
  2. Newcomer, M.E. and D.E. Ong. (2000) Biochim. Biophys. Acta 1482:57.
Entrez Gene IDs
5950 (Human); 19662 (Mouse); 25703 (Rat)
Alternate Names
interstitial; Plasma retinol-binding protein; RBP4; retinol binding protein 4, plasma; RetinolBinding Protein 4; retinol-binding protein 4, plasma

Citations for Recombinant Human RBP4 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.

2 Citations: Showing 1 - 2
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  1. IGF-1R deficiency in human keratinocytes disrupts epidermal homeostasis and stem cell maintenance
    Authors: T Muraguchi, D Nanba, EK Nishimura, T Tashiro
    J. Dermatol. Sci., 2019;0(0):.
    Species: Human
    Sample Types: Whole Cells
    Applications: Bioassay
  2. A multiplex immunoassay for human adipokine profiling.
    Authors: Schipper HS, De Jager W, van Dijk ME, Meerding J, Zelissen PM, Adan RA, Prakken BJ, Kalkhoven E
    Clin. Chem., 2010;56(0):1320.


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