Assay principle

Running your 5HT1A receptor binding assay using Tag-lite is as easy as it can gets. Simply dispense 10 µL of labeled cells into each well, followed by 5 µL of labeled ligand and 5 µL of the compound you wish to test. Like all HTRF assays, Tag-lite assays do not require any washing steps. A diagram of the procedure to be followed is given on the right.

Saturation binding (KD)

A saturation binding assay measures total and non-specific binding for increasing concentrations of ligand under equilibrium conditions. To perform the assay, the fluorescent ligand is titrated into a solution containing a fixed amount of labeled cells and then incubated to equilibrium. The HTRF ratio obtained from this titration is the total binding.

Competitive binding (KI)

A competitive binding assay is performed to measure the dissociation constant, Ki. To perform the assay, the compound is titrated into a solution containing a fixed concentration of fluorescent ligand and a fixed amount of cells.

Kd and Ki validation

Examples of data obtained using Serotonin 5HT1A labeled cells and their matching fluorescent ligand (L0029RED). WAY-100135 was used as reference ligand. Results may vary from one HTRF® compatible reader to another.