Figure 7

Concentration dependent binding of [ ³ H] Astemizole to crude membranes. Crude membranes corresponding to 200 μg total membrane protein content were incubated with [ ³H]-Astemizole in ranges of 0.5 - 20 nM with and without a surplus of 10 μM unlabeled Astemizole at 15°C for 2 hours. Membrane bound ligand was quantified by liquid scintillation counting and normalized to sample volumes and protein content to determine total (blue squares), unspecific (open triangles) and specific binding (red triangles) as pmol bound [ ³H]-Astemizole/mg crude membrane protein. Nonlinear regression was used to fit the experimental data to a Michaelis-Menten equation as described in Methods.