Solubilization of muscarinic acetylcholine receptors from mammalian brain: An analytical approach

Muscarinic receptor sites were extracted from microsomal membranes of mammalian brain using digitonin. These detergent preparations were submitted to the control of unambiguous solubilization criteria, and were found to correspond to molecularly dispersed material. In contrast, the corresponding salt preparations did not fulfill these criteria. After comparing various assay methods, we describe a simple and rapid charcoal adsorption binding technique, which was selected for measuring digitonin-extracted muscarinic receptors. Under these conditions the digitonin preparations, from four different species revealed identical biochemical properties in a stereospecific labeling system using [ 3H]dexetimide and [ 3H]levetimide.