SCINTILLATING MICROTITRATION PLATES AS PLATFORM FOR DETERMINATION OF [H-3] ESTRADIOL BINDING CONSTANTS FOR HER-HBD

A novel approach to direct determination of ligand binding constants f or the human estrogen receptor hormone binding domain was developed. R ecombinantly produced human receptor in yeast extracts was attached to scintillating microtitration plates. Radioligand binding to receptors was determined in a multi-detector scintillation counter designed for the microtitration plate format. The method was emploed in equilibriu m binding experiments, in binding competition tests and in determinati on of kinetic rate constants. The results obtained show that the metho dology is valid in comparison to previously published data regarding h ormone binding characteristics of estrogen receptors. Furthermore, the methodology offers several advantages over previous binding assays be cause the scintillating microtitration plates constitute both the bind ing reaction vial and the scintillant for the detection of bound radio activity.