RETINOL-BINDING PROTEIN (RBP)/RBP4 ELISA KIT
INTENDED USE
The Retinol-binding protein (RBP)/RBP4 ELISA Kit Assay is intended for the quantitative determination of free Retinol-binding protein (RBP)/RBP4 as well as RBP4 complexed with transthyretin in plasma, serum and urine. For in vitro diagnostic use only.
SUMMARY AND EXPLANATION OF THE TEST
Retinol-binding protein (RBP)/RBP4is a small (21kD) transport protein for vitamin A which forms a complex with prealbumin in blood but loses its affinity for prealbumin once the vitamin has been delivered to the target cells. The free RBP/RBP4 molecule is rapidly filtered at the glomerulus and catabolized in the renal tubules after resorption by the proximal tubular cells (like other small molecules e.g. ß-2 microglobulin). In kidney disease with prevailing tubular changes these proteins are not reabsorbed and appear in the urine.
As published by Yang et al. (2005) the retinol-binding protein (RBP)/RBP4 eems to play a key role in the development of insulin resistance. The fat cell derived peptide RBP/RBP4 also modulates the glucose homeostasis and impairs the insulin sensitivity as well as insulin resistance. The elevation of serum RBP/RBP4 causes systemic insulin resistance, whereas its reduction improves the insulin action.
As a conclusion from the results, the authors suggest that RBP/RBP4 alters insulin sensitivity in part by affecting insulin signalling in muscle through alterations in the amount of tyrosine-phosphorylated IRS-1 and PI(3)K activation. Thus, RBP/RBP4 may contribute to the pathogenesis of type 2 diabetes, and lowering RBP/RBP4 could be a new strategy for treating type 2 diabetes.
PRINCIPLE OF THE TEST
Retinol-binding protein (RBP)/RBP4 ELISA Kit
This Retinol-binding protein (RBP)/RBP4 ELISA Kit can be used for quantitative determination of Retinol-binding protein (RBP)/RBP4 in plasma, serum and urine. In a first incubation step, RBP/RBP4 in the samples is bound to polyclonal rabbit anti RBP/RBP4 antibodies, immobilized on the microtitre plate. A peroxidase-conjugated anti RBP/RBP4 antibody is used for detection and quantification, and tetramethylbenzidine (TMB) as a peroxidase substrate. A dose response curve of absorbance unit (optical density at 450 nm) vs. concentration is generated using the values obtained from standard. RBP/RBP4 present in the patient samples is determined directly from this curve.
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