Acetylcholine receptor: similarity in axons and junctions.

Sulfur and selenium iso logs of benzoylcholine and its tertiary analog differ greatly in their abilities to block the electrical activity of squid axons. Presumably, differences in the biological activities of these compounds can be correlated with differences in their electron distribution. The relative effects on axons parallel those on junc tions of the electroplax, suggesting the presence of similar receptors.