Table III.

Effect of Gα Activators on In Vitro Lysosome–Lysosome Fusion

Sample		Percent fusion
+ ATP		33.0 ± 0.5
− ATP		2.0 ± 1.0
10 μg/ml Ptx		10.9 ± 0.7
50 μg/ml Ptx		0.5 ± 0.0
50 μg/ml Ptx, − NAD		26.2 ± 0.3
10 μg/ml Chtx		30.9 ± 0.8
50 μg/ml Chtx		32.5 ± 0.4
50 μg/ml Chtx, − NAD		26.9 ± 0.6

In vitro fusion was carried out as described in Materials and Methods using purified lysosomes. Toxins were pretreated with DTT preincubation as described previously (Colombo et al., 1992b ). Treated toxin and NAD were added to the vesicles and the complete fusion reaction was added subsequently.