Pore-forming protein that forms cation-selective hydrophilic pores of around 1 nm and causes hemolysis. Pore formation is a multi-step process that involves specific recognition of membrane sphingomyelin (but neither cholesterol nor phosphatidylcholine) using aromatic rich region and adjacent phosphocholine (POC) binding site, firm binding to the membrane (mainly driven by hydrophobic interactions) accompanied by the transfer of the N-terminal region to the lipid-water interface and finally pore formation after oligomerization of monomers (By similarity). This protein shows potent hemolytic activity (EC(50)=8.8 ng/ml) that is specifically inhibited by sphingomyelin. Shows no phospholipase A2 activity, nor antimicrobial activity against the four bacteria tested. Is lethal to crayfish (Ref.1). Tetramer in the presence of a lipidic interface. Monomer, in soluble state. Forms an alpha-helical membrane channel in the prey. The N-terminal region, before the pore is formed, is bound to the lipid membrane. It partitions into the lipid-water interface and stabilizes the monomeric molecule on the membrane. Finally, it traverses the bilayer, thus forming the transmembrane pore. LD(100) is 0.58 mg/kg to crayfish. Belongs to the actinoporin family. Sea anemone subfamily.