FIG. 7.

ATPase activity. Antibody complexes isolated from HeLa cells in parallel with those used in the HAT assay (Fig. 6) were assayed for associated ATPase activity. Equal amounts of total cell protein were immunoprecipitated with the appropriate antibody. ATPase activity was measured in a thin-layer chromatography assay as the ability to hydrolyze the terminal phosphate from [γ-³²P]ATP. The percent conversion from ATP-bound ³²P to free ³²P_i was quantified on a Fuji phosphoimaging system. The results shown are the averages of six independent experiments.