1678 Pore - Forming Protein from E

Entamoeba histolytica, an enter ic h u m a n paras i te , produces extensive tissue des t ruc t ion in the course of the infection. Pr ior studies from this l abo ra to ry have discussed the isolation o f the p l a sma m e m b r a n e of this paras i te and charac te r ized cer ta in o f its intr insic po lypept ides and externa l ly disposed ant igens (1, 2). More recent interests have focused on the role of the p l a sma m e m b r a n e in the cytotoxic i ty o f amoebae . Here, close appos i t ion be tween a m o e b a a n d target cell m e m b r a n e s are a prerequis i te for the extensive cytolysis seen on a wide spec t rum of cell types (3-8). In this s tudy we deal wi th one componen t of the m e m b r a n e of E. histolytica tha t m a y be involved in the cytotoxic mechanism. W e have pa r t i a l l y pur i f ied a po lypep t ide tha t inserts into m e m b r a n e bi layers and opens aqueous pores. T h e conduc tance changes tha t this poreforming mate r i a l (PFM) 1 media tes can be resolved into ind iv idua l ion channels.