– A cholesterol-dependent toxin that causes cytolysis by forming pores in cholesterol containing host membranes. After binding to target membranes, the protein undergoes a major conformation change, leading to its insertion in the host membrane and formation of an oligomeric pore complex. Cholesterol is required for binding to host membranes, membrane insertion and pore formation; cholesterol binding is mediated by a Thr-Leu pair in the C-terminus. Can be reversibly inactivated by oxidation. Pneumolysin Protein, S. pneumoniae serotype 4, Recombinant (Avi & His) is expressed in E. coli expression system with N-6xHis-Avi tag. The predicted molecular weight is 58.7 kDa and the accession number is P0C2J9.