A polypeptide toxin from the coral Goniopora: Purification and action on Ca 2+ channels

A polypeptide toxin has been isolated from Goniopora coral with an M r of 19000. Goniopora toxin has the following properties: (i) it induces contraction of guinea pig ileum and this contraction is prevented by Ca 2+-channel blockers; (ii) it stimulates 45Ca 2+ influx in cardiac cells in culture and this stimulation is abolished by Ca 2+-channel blockers; (iii) it prevents binding of (+)-[ 3H]PN 200-110 to the Ca 2+-channel protein of skeletal muscle T-tubule membranes. All these results taken together suggest that Goniopora toxin is a Ca 2+-channel activator.