[Structural transitions of the Torpedo cholinergic receptor in its membrane state as demonstrated by a fluorescent local anesthetic: quinacrine].

Differential fluorescence emissions of receptor-rich membrane fragments prepared from Torpedo marmorata electric organ and labelled by a fluorescent local anesthetic quinacrine are obtained by energy transfer. Addition of a cholinergic effector causes two classes of structural transitions, fast and slow, which are related to the agonist or antagonist character of the ligand.