Saturation Assay (BMAX & Kd)
Multiple concentrations (up to twelve) of the radioligand are incubated in triplicate or quadruplicate with either cell, or tissue homogenate containing the target receptor of interest.
After equilibrium has been reached, receptor-bound radioligand is separated from non-bound radioligand using either;
- Filter-based Separation
- Scintillation Proximity Assay (SPA)
The filters or SPA plate are counted using liquid scintillation counting to determine the level of receptor-bound radioligand and the results plotted to obtain the receptor density (BMAX) and if desired the Kd for the receptor-radioligand integration.