Fig. 6.
Effect of erbstatin analog on p85 and p110 phosphorylation, in vitro. PI3K was immunoprecipitated (IP) from Triton-soluble fractions of resting platelet lysates. Isotype-matched IgG1 antibody was used as a control (lane 1). Washed immune complexes were incubated in the absence or presence of the indicated concentrations of Erb-A for 15 minutes, and subjected to an in vitro kinase assay in the presence of γ-32P-ATP, and Mn2+ as described in Materials and Methods. In the absence of erb-A, kinase buffer alone (lanes 1 and 2), or ethanol/buffer vehicle (lane 3) were used as controls.32P-labeled proteins were eluted, separated by SDS-PAGE, and identified by autoradiography. Molecular mass markers in kilodaltons are indicated at the left.