The heterogeneity and nucleotide modulation of cholinergic muscarinic receptors are restored by poly (ethylene) glycol-6000 precipitation of solubilized atrial receptors.

The membrane bound muscarinic receptor exhibits heterogeneity of binding sites for agonists that are modulated by guanine nucleotides. These properties are generally lost upon receptor solubilization by several detergents, but may be recovered after rapid detergent removal by poly (ethylene) glycol-6000 precipitation of the digitonin plus cholate solubilized atrial muscarinic receptor. The results are discussed in terms of muscarinic receptor interactions in the intact membrane.