FIGURE 4.

Effect of preincubation time (hPLCβ3 with U73122) on the U73122-mediated activation of hPLCβ3 in DDM-mixed micelles. U73122 was preincubated with hPLCβ3 at 40 μm in assay buffer (50 μl total volume) for the indicated times in the absence of PIP₂ and DDM. Preincubation was quenched with the addition of 1 mm glutathione. Assays were initiated by the addition of preincubated enzyme to mixed micelles in a final volume of 100 μl, and incubation times were adjusted to ensure that less than 15% PIP₂ was hydrolyzed in all cases. Data represent mean ± S.D. from triplicate determinations from one representative experiment.