HAGP inhibits PKC kinase activity in vitro. (A) Recombinant, human PKCα (50 ng) was pretreated with the indicated concentrations of HAGP monomers for 15 minutes at 37°C and stimulated with 16 μM PMA in the presence of a fluorescent peptide substrate. Basal kinase activity in the absence of HAGP and PMA is shown by the dashed line (*P < .04 for 20 and 40 µM HAGP treatment vs no HAGP; n = 7). (B) PKCα was pretreated with control vesicles containing 95 mol% DOPC and 5 mol% DOPS (solid line), or HAGP vesicles containing 75 mol% DOPC, 5 mol% DOPS, and 20 mol% HAGP (dashed line) and stimulated with separate vesicles containing DAG (16 μM final), and phosphorylation was measured as above (*P < .05 for HAGP vs control; n = 6). (C) Human, recombinant PKCδ was pretreated as in panel A. Basal kinase activity in the absence of HAGP is depicted by the dashed line, whereas PMA stimulation is shown by the solid line (n = 5).