FIG. 2.

pH range of acid pulse-induced entry of TcsL. In a 96-well plate, CHO cells (5 × 10⁴ cells/well) were incubated with bafilomycin A1 (5 × 10⁻⁷ M) in a final volume of 100 μl for 30 min. The cells were then treated with TcsL (1 pmol) for 1 h at 37°C, subjected to a 10-min pH pulse across a range of pHs, and finally returned to pH 7.8 by addition of neutralized medium. Samples were observed for 11 h, and CPE were determined by visualization. Similar effects were determined for CHO, HeLa, and RAW cells. Curves: A, pH 4.0; B, pH 4.5; C, pH 5.0; D, TcsL (no pulse); E, pH 5.5; F, pH 6.0; G, pH 6.5; H, pH 7.0; I, pH 7.5.