Comparison of the interactions of a specific neurotoxin (.alpha.-bungarotoxin) with the acetylcholine receptor in Torpedo californica and Electrophorus electricus membrane preparations

Publisher Website
Google Scholar
Abstract
.alpha.-Bungarotoxin, a snake neurotoxin, binds irreversibly and specifically to the acetylcholine receptor isolated from the electroplax of E. electricus and Torpedo spp. and is an important tool in the study of the receptor-ligand binding mechanism. Two distinct kinetic processes were observed in studies with membranes from E. electricus. A minimum mechanism for the toxin reaction involves the reversible binding of 2 toxin molecules to the receptor prior to the irreversible formation of toxin:receptor complexes and a toxin-induced conformational change of the receptor which leads to an increase in the affinity of the receptor binding sites for toxin. Only 1 process was detected in Torpedo membranes. The study was conducted to determine whether the receptors in T. californica and E. electricus membranes have different properties or whether the measurements and their interpretation were responsible for the different results. Two methods which are frequently used in binding studies to separate free and bound toxin, a CM-52 cellulose minicolumn assay and DE-81 filter disk assay, were compared. The interaction of toxin with receptor from T. californica is similar to that observed with receptor from E. electricus. The apparent differences which were reported have arisen from the design of the experiments in which T. californica membranes were used.

This publication has 1 reference indexed in Scilit: