A potassium channel toxin from the secretion of the sea anemone Bunodosoma granulifera. isolation, amino acid sequence and biological activity

A peptide toxin affecting potassium channels was isolated from the sea anemone Bunodosoma granulifera. It facilitates acetylcholine release at avian neuromuscular junctions, competes with dendrotoxin I, a probe for voltage-dependent potassium channels, for binding to synaptosomal membranes of rat brain with a K i of 0.7 nM and supresses K + currents in rat dorsal root ganglion neurones in culture. It represents a new structural type of potassium channel toxin with the sequence V 1RCDWFKETA 10CRHAKSLGNC 20RTSQKYRANC 30AKTLQCC 37 ( M r 4275, three disulfides).