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A study to account for the differences between the acetylcholine (ACh) dose-response relationships of the alpha3beta2 and alpha3beta4 receptors shows that amino acids in the first 120 residues of beta2 and the corresponding region of beta4 result in an agonist binding site that links the alpha and beta subunits in neuronal nicotinic receptors. In Xenopus oocytes, the alpha3beta2 receptor exhibits an EC(sub 50) for ACh is equivalent to 20-fold less than the EC(sub 50) of the alpha3beta4 receptor.

Permeation properties of the cystic fibrosis transmembrane conductance regulator (CTFR) were studied with the aid of diphenylamine-2-carboxylate (DPC) and flufenamic acid (FFA) blocking agents. The blockade is dependent on voltage, affecting currents at positive potentials alone, which implies an open-channel block. Depolarizing membrane voltages cause continuous bursts for up to ten seconds, hyperpolarizing voltages cause interrupted bursts. Vm flickers attested to the permeation of drugs through the membrane. The binding site for both drugs was the same FFA and DPC voltage-dependent blockage aid in the study of CTFR structure-functions.