Molecular pharmacology of the calcium channel

No powerful toxin is yet known which alters calcium channel function in an analogous way as the neurotoxins do for, for example, the sodium channel.

Abstract

Ion channels in plasmamembranes have many features in common: ion binding sites; multiple, allosterically coupled drug or toxin receptor sites; subunit composition; glycoprotein nature; regulatory sites as targets for control mechanisms as are kinases and phosphatases; and tissue-specific heterogeneity. These features have been elucidated extensively for the voltage-dependent sodium channel (Catterall, 1984). The tools required to biochemically identify, characterize, isolate and reconstitute these channels were mainly provided by nature itself. The sodium channel contains at least four different neurotoxins binding sites which, upon binding the appropriate ligand, alter the channel function in a highly specific manner. Radiolabelled toxins have been essential for these achievements. With the exception of maitotoxin (Takahashi, et al., 1982) no powerful toxin is yet known which alters calcium channel function in an analogous way as the neurotoxins do for, for example, the sodium channel.