Characterization of putative nicotinic acetylcholine receptors solubilized from rat brains.

A membrane component of rat brains which binds [3H]acetylcholine in the presence of eserine and atropine was solubilized by various detergents and characterized. The affinity of this component for [3H]acetylcholine was increased 2-3-fold upon dissolution with non-ionic detergents. Pharmacological specificity of this component suggested its nicotinic cholinergic nature. The component cross-reacted with antisera raised against nicotinic acetylcholine receptors of Torpedo marmorata or Narke japonica. The component interacted with wheat germ agglutinin-conjugated Sepharose 4B, suggesting that it may be a glycoprotein, but did not bind appreciably to alpha-bungarotoxin-conjugated Sepharose 4B. Conversely, alpha-bungarotoxin binding component in the same preparation, which was bound to the toxin-conjugated gels, did not bind [3H]acetylcholine. These results demonstrate that nicotinic acetylcholine binding component and alpha-bungarotoxin binding component in brain membranes are distinct molecules and can be separated from each other.