This family consists of several bacterial and fungal Aegerolysin-like proteins. It has been found that aegerolysin and ostreolysin are expressed during formation of primordia and fruiting bodies. It has been suggested that these haemolysins play an important role in initial phase of fungal fruiting. The bacterial members of this family are expressed during sporulation. Ostreolysin was found cytolytic to various erythrocytes and tumor cells. It forms transmembrane pores 4 nm in diameter. The activity is inhibited by total membrane lipids, and modulated by lysophosphatides. The potential use of aegerolysins is reviewed with special emphasis on their properties which would allow their use in therapeutics. Aegerolysin is part of the pleurotolysin pore-forming (Pleurotolysin) transporter superfamily. Member proteins assemble into a transmembrane pore complex.