Affinity Partitioning of Receptor-Rich Membrane Fractions and Their Purification

Abstract

The study of the molecular properties of membrane bound receptors is greatly facilitated by their solubilization and purification. An excellent example of this is the nicotinic acetylcholine receptor, which can be solubilized by the use of nonionic detergents and purified by affinity chromatography (15, 20). Initial studies indicated that the binding properties of the nicotinic receptor remain intact in the presence of nonionic detergents. Such fortuitous circumstances do not occur in the study of other receptors. For example, the muscarinic acetylcholine receptor has proved rather labile to treatment with nonionic detergents (7), resulting in considerable loss of binding properties. Even when binding properties of a receptor are intact after solubilization, questions often remain concerning the in situ structure of the receptor and its associated activities. For example, functional coupling between receptor and enzymatic activities and ionophores may be disrupted or altered upon solubilization. Even in the case of the nicotinic receptor, differences in the binding properties of solubilized and membrane bound receptors have been detected (5).