TOXIC PRINCIPLE OF SELVA ANT VENOM IS A PORE-FORMING PROTEIN TRANSFORMER

Ectatomin (Ea) is a newly isolated main toxic component of Ectatomma t uberculatum ant venom. Structural and electrophysiological studies wer e performed with purified Ea. The protein consists of two homologous p olypeptide chains (37 and 34 residues) and forms a four alpha-helix bu ndle in aqueous solution. On insertion into artificial bilayer membran es, two Ea molecules form an ion pore. Our results suggest that the 'i nside-out' mechanism of pore formation requires a significant movement of Ea helical parts. The pore formation in the cell membrane might we ll explain the toxic activity of Ea, not excluding at the same time it s intracellular activities.