Extraction of peripheral proteins from nicotinic acetylcholine receptor-enriched membranes

The solubilisation of membrane proteins from nicotinic acetylcholine receptor-enriched membranes from the electric organ of Torpedo marmorata was studied. Chaotropic ions were shown to be ineffective in extracting peripheral proteins from these membranes. Two different anhydrides, 2, 3-dimethylmaleic and 3,4,5,6-tetrahydrophthalic anhydride, released certain peripheral membrane proteins but not the integral receptor protein. Treatment of membranes containing greater than 3 nmol alpha-bungarotoxin binding sites per mg protein with anhydride resulted in a 43 kDa polypeptide as the major constituent of the solubilised material. The nature of the 43 kDa polypeptide is discussed. Gentle anhydride treatment did not change the alpha-bungarotoxin and carbamoylcholine binding properties of the receptor.