FIGURE 4.

CTA1 activity in the presence of lipid raft LUVs. 2-fold dilutions of CTA1 were mixed with lipid raft LUVs at 25 °C for toxicity assays performed at 25 °C (open squares) or 37 °C (filled squares). For a third condition, LUVs were added after the toxin had been heated to 37 °C for 30 min (filled triangles). This toxin-LUV mixture was incubated at 37 °C for an additional hour before initiating the toxicity assay. Toxin samples incubated in the absence of LUVs at 25 °C (open circles) or 37 °C (filled circles) were also used for the assay. Four samples were used for each condition; results are presented as means ± S.E. (error bars). One of three representative experiments is shown.