Figure 3. Stability of the ligand binding capacity of CfEcR/CfUSP complexes to irradiation at 300 (squares) or 350 nm (circles). Receptor complexes were irradiated in the absence of ligand and remaining specific binding was determined by subsequent addition of [3H]ponasterone A ( 250-fold excess of unlabelled ponasterone A). Results shown are the mean values of duplicate samples; variation between replicates is 5% or less.