FIG. 1.

Binding of AC toxin to Jurkat cells and sheep RBC is both calcium and acylation dependent. Cells in 2 mM EDTA or 1.2 mM free calcium were treated with AC toxin (10 μg/ml) or unacylated (by virtue of omission of cyaC) AC toxin (10 μg/ml) for 30 min at 37°C as indicated in Materials and Methods. Solid line, flow cytometric histogram of control cells; bold solid line, AC toxin; dotted line, unacylated AC toxin. Data presented are representative of seven separate flow cytometry experiments for sheep RBC and two separate experiments for Jurkat cells.