Acetylcholine-binding substance extracted by using organic solvent and acetylcholine receptor of electric organ of Narke japonica.

1. Proteolipid was extracted from the electric organ of Narke japonica by using chloroform/methanol (2:1, v/v). This extract was separated into acetylcholine-binding and non-binding substances by column chromatography. However, acetylcholine-binding substances did not show the characteristic properties of protein. 2. The membrane fragments of the electric organ were separated into three main parts by sucrose density gradient centrifugation. From the heaviest, the fractions were acetylcholine receptor rich, ATPase rich, and acetylcholinesterase rich. 3. The membrane fraction having acetylcholine receptor showed the excitability, the increase of Na+ permeability by the application of cholinergic agonists. However, the acetylcholine binding substance extracted by the organic solvent was richer in the lighter fraction. This substance differed from the true acetylcholine receptor.