Retinol-binding protein RBP/RBP4 (1 point calibration) ELISA

The Retinol-binding protein RBP/RBP4 ELISA kit is an enzyme immunoassay intended for the quantitative determination of free retinol-binding protein RBP/RBP4 as well as RBP4 complexed with transthyretin in plasma, serum and urine. 

Retinol-binding protein RBP/RBP4 is a 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 catabolised in the renal tubules after resorption by the proximal tubular cells. In kidney disease with prevailing tubular changes, these proteins are not reabsorbed and appear in the urine. 

The elevation of serum RBP/RBP4 causes systemic insulin resistance, whereas its reduction improves the insulin action.