Neuronal calcium channel antagonists. Discrimination between calcium channel subtypes using omega-conotoxin from Conus magus venom.
The omega-conotoxins from the venom of fish-hunting cone snails are probably the most useful of presently available ligands for neuronal Ca channels from vertebrates. Two of these peptide toxins, omega-conotoxins MVIIA and MVIIB from the venom of Conus magus, were purified. The amino acid sequences show significant differences from omega-conotoxins from Conus geographus. Total synthesis of omega-conotoxin MVIIA was achieved, and biologically active radiolabeled toxin was produced by iodination. Although omega-conotoxins from C. geographus (GVIA) and C. magus (MVIIA) appear to compete for the same sites in mammalian brain, in amphibian brain the high-affinity binding of omega-conotoxin MVIIA has narrower specificity. In this system, it is demonstrated that a combination of two omega-conotoxins can be used for biochemically defining receptor subtypes and suggested that these correspond to subtypes of neuronal Ca2+ channels.
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D002645:Chickens; D007473:Ion Channels / Q000187:drug effects* / Q000378:metabolism; D008978:Mollusk Venoms / Q000138:chemical synthesis / Q000302:isolation & purification* / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism*; D020866:omega-Conotoxin GVIA
D002121:Calcium Channel Blockers; D007473:Ion Channels; D008978:Mollusk Venoms; D020866:omega-Conotoxin GVIA; D002118:Calcium