A polypeptide toxin from the coral Goniopora. Purification and action on Ca2+ channels

A polypeptide toxin has been isolated from Goniopora coral with an Mr of 19 000. Goniopora toxin has the following properties: it induces contraction of guinea pig ileum and this contraction is prevented by Ca2+-channel blockers; it stimulates 45Ca2+ influx in cardiac cells in culture and this stimulation is abolished by Ca2+-channel blockers; it prevents binding of (+)-[3H]PN 200-110 to the Ca2+-channel protein of skeletal muscle T-tubule membranes. All these results taken together suggest that Goniopora toxin is a Ca2+-channel activator.