“…Almost all of the methods that underlie the results in this paper have been discussed elsewhere: preparation of liposomes [5], assay of colicin ion channel activity in liposomes [5] and planar bilayers [13,14], determination of potential-dependent insertion of colicin E1 channel peptide into liposomes [15], proteolysis of soluble channel peptides and peptide bound to liposomes [8,14], acrylamide quenching of fluorescence 73 probes internal to colicin channel peptides [14], partition of colicin channel peptide into non-ionic detergent [14], cytotoxicity [16,17], trypsin rescue of colicin-treated cells under cytotoxic conditions [17], colicin-induced K + efflux [18], and site-directed mutagenesis [16].…”