FIGURE 4.

Effect of BAR domain on activity of ASAP-type Arf GAPs. A, ASAP1. Panel a, PZA of ASAP1 was titrated into a reaction containing myrArf1-GTP and LUVs of two compositions with either DSPC or egg PC (total phospholipid concentration of 500 μm) extruded through two pore sizes, 1 or 0.1 μm. Panel b, an experiment similar to that described for A but with BAR-PZA as enzyme. Experiments were performed three times, and representative results are shown. B, ASAP3. ASAP3 or [ΔBAR]ASAP3 were titrated into a reaction containing LUVs composed of 55% DSPC, 20% PE, 15% PS, 7.5% PI, and 2.5% PIP₂ and extruded through 0.1-μm pores. myrArf5 was the substrate. The plotted data are from a representative experiment. The C50 value presented is the mean ± S.E. from four experiments.