Binds specifically to voltage-gated sodium channels (Nav) (site 3), thereby delaying their inactivation during signal transduction. Has a strong effect on crustaceans and insects and a weaker effect on mammals. It strongly inhibits D.melanogaster sodium channel (DmNav1). It weakly inhibits the brain sodium channel Nav1.2/SCN2A. It strongly affects the heart sodium channels (Nav1.5/SCN5A). This protein is encoded by at least 3 different genes. At least 3 other genes code for a similar Av2 with an Ile (instead a Val) at position 34. Belongs to the sea anemone sodium channel inhibitory toxin family. Type I subfamily. Opinions are divided on whether Anemonia viridis (Forsskal, 1775) and Anemonia sulcata (Pennant, 1777) are separate species.