The Quantikine Human RBP4 immunoassay is a 2.5 hour solid phase ELISA designed to measure human RBP4 in cell culture supernates, serum, plasma, urine, and saliva. It contains NS0-expressed recombinant human RBP4 and has been shown to accurately quantitate the recombinant factor. Results obtained using natural human RBP4 showed linear curves that were parallel to the standard curves obtained using the Quantikine kit standards. These results indicate that this kit can be used to determine relative mass values for naturally occurring human RBP4.
Intra-Assay Precision (Precision within an assay) Three samples of known concentration were tested on one plate to assess intra-assay precision.
Inter-Assay Precision (Precision between assays) Three samples of known concentration were tested in separate assays to assess inter-assay precision.
The recovery of RBP4 spiked to levels throughout the range of the assay was evaluated.
Average % Recovery
Cell Culture Media (n=4)
To assess the linearity of the assay, samples containing and/or spiked with high concentrations of RBP4 were serially diluted with the Calibrator Diluent to produce samples with values within the dynamic range of the assay.
Preparation and Storage
Store the unopened product at 2 - 8 °C. Do not use past expiration date.
Background: RBP4/Retinol-Binding Protein 4
Retinol-binding protein 4 (RBP4) is a Lipocalin superfamily molecule that transports vitamin A (retinol) and retinaldehyde in the serum. Retinaldehyde is the critical chromophore in the rhodopsin photoreceptor, while both it and retinoic acid regulate a multitude of cellular differentiation and proliferation effects through the intracellular receptors RAR and RXR. RBP4 is secreted primarily by hepatocytes and adipocytes into the blood where the RBP4-retinol complex interacts with transthyretin (TTR). Formation of the complex with TTR increases the serum half-life of RBP4 by preventing RBP4 filtration through the kidney. The C-terminally processed forms of RBP4, which do not bind TTR, are normally excreted into the urine but accumulate in the serum during renal failure. RBP4 promotes hyperglycemia, and its upregulation in visceral and liver adipocytes leads to elevated serum levels.
Entrez Gene IDs
5950 (Human); 19662 (Mouse); 25703 (Rat);
interstitial; Plasma retinol-binding protein; RBP4; retinol binding protein 4, plasma; RetinolBinding Protein 4; retinol-binding protein 4, plasma;
Refer to the product for complete assay procedure.
Bring all reagents and samples to room temperature before use. It is recommended that all samples, standards, and controls be assayed in duplicate.
Prepare all reagents, standard dilutions, and samples as directed in the product insert.
Remove excess microplate strips from the plate frame, return them to the foil pouch containing the desiccant pack, and reseal.
200 µL Assay Diluent
Add 200 µL of Assay Diluent to each well.
20 µL Standard, Control, or Sample
Add 20 µL of Standard, control, or sample to each well. Cover with a plate sealer, and incubate at room temperature for 1 hour on a horizontal orbital microplate shaker.
Aspirate each well and wash, repeating the process 3 times for a total of 4 washes.
200 µL Conjugate
Add 200 µL of Conjugate to each well. Cover with a new plate sealer, and incubate at room temperature for 1 hour on the shaker.
Aspirate and wash 4 times.
200 µL Substrate Solution
Add 200 µL Substrate Solution to each well. Incubate at room temperature for 30 minutes on the benchtop. PROTECT FROM LIGHT.
50 µL Stop Solution
Add 50 µL of Stop Solution to each well. Read at 450 nm within 30 minutes. Set wavelength correction to 540 nm or 570 nm.
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